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  • 1.
    Abdel Rehim, Abbi
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Abdel Rehim, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Screening and determination of drugs in human saliva utilizing microextraction by packed sorbent and liquid chromatography-tandem mass spectrometry2013Inngår i: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 27, nr 9, s. 1188-1191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study presents a new method for collecting and handling saliva samples using an automated analytical microsyringe and microextraction by packed syringe (MEPS). The screening and determination of lidocaine in human saliva samples utilizing MEPS and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were carried out. An exact volume of saliva could be collected. The MEPS C-8-cartridge could be used for 50 extractions before it was discarded. The extraction recovery was about 60%. The pharmacokinetic curve of lidocaine in saliva using MEPS-LC-MS/MS is reported.

  • 2. Abdel-Rehim, Abbi
    et al.
    Abdel-Rehim, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Advantages of Saliva Sampling in Bioanalysis Using Microextraction by Packed Sorbent and Dried Saliva Spot with LC-MS-MS2014Inngår i: LC GC Europe, ISSN 1471-6577, Vol. 27, nr 10, s. 529-531Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Saliva offers a fast and non-invasive sampling matrix for determining drug concentration levels, making it a suitable alternative to plasma and blood. During the analysis of biological samples attention is focused on sample pre-treatment. In addition, liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS) is often the method of choice in bioanalysis because of the good selectivity and good sensitivity of the technique. In this article, two sample handling and sample preparation methods for saliva samples are presented and discussed. The first method is microextraction by packed sorbent (MEPS), and the second method is dried saliva spot (DSS). Both methods were applied for determining the presence of lidocaine in saliva.

  • 3. Abdel-Rehim, Abbi
    et al.
    Abdel-Rehim, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Dried saliva spot as a sampling technique for saliva samples2014Inngår i: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 28, nr 6, s. 875-877Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For the first time, dried saliva spot (DSS) was used as a sampling technique for saliva samples. In the DSS technique 50 L of saliva was collected on filter paper and the saliva was then extracted with an organic solvent. The local anesthetic lidocaine was used as a model compound, which was determined in the DSS using liquid chromatography and mass spectrometry. The results obtained for the determination of lidocaine in saliva using DSS were compared with those from a previous study using a microextraction by packed sorbent syringe as the sampling method for saliva. This study shows that DSS can be used for the analysis of saliva samples. The method is promising and very easy in terms of sampling and extraction procedures. The results from this study are in good agreement with those from our previous work on the determination of lidocaine in saliva. DSS can open a new dimension in the saliva handling process in terms of sampling, storing and transport.

  • 4.
    Abdel-Rehim, Abbi
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Abdel-Rehim, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Evaluation of microextraction by packed sorbent and micro-liquid chromatography-tandem mass spectrometry as a green approach in bioanalysis2013Inngår i: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 27, nr 10, s. 1225-1233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study the use of micro-liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was investigated in routine bioanalysis application for separation and quantification of pro-drug AZD6319 (developed for aldezheimer treatment). Microextraction by packed sorbent (MEPS) was used as sample clean-up method. The focus of this study was put on the evaluation of the usability of smaller column diameters such as 1.0 and 0.3mm instead of 2.1mm in bioanalysis application to reduce solvent consumption and sample volumes. Solvent consumption was reduced by 80% when a 1.0mm column was used compared with 2.1mm column. Robustness of the micro-columns in terms of accuracy and precision was investigated. The application of LC-MS/MS for the quantitative analysis of AZD6319 in plasma samples showed good selectivity, accuracy and precision. The coefficients of determination (R-2) were >0.998 for all runs using plasma samples on the studied micro-columns. The inter-day accuracy values for quality control samples ranged from 99 to 103% and from 96 to 105% for 0.3x50mm and 1.0x50mm columns, respectively. The inter-day precision values ranged from 4.0 to 9.0% and from 4.0 to 8.0% for 0.3x50 and 1.0x50mm columns, respectively. In addition the sensitivity was increased by three times using a 1.0mm column compared with 2.1mm. Furthermore, robustness of the micro-columns from different manufacturers was investigated.

  • 5.
    Abdel-Rehim, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Microextraction by packed sorbent (MEPS): A tutorial2011Inngår i: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 701, nr 2, s. 119-128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This tutorial provides an overview on a new technique for sample preparation, microextraction by packed sorbent (MEPS). Not only the automation process by MEPS is the advantage but also the much smaller volumes of the samples, solvents and dead volumes in the system. Other significant advantages such as the speed and the simplicity of the sample preparation process are provided. In this tutorial the main concepts of MEPS will be elucidated. Different practical aspects in MEPS are addressed. The factors affecting MEPS performance will be discussed. The application of MEPS in clinical and pre-clinical studies for quantification of drugs and metabolites in blood, plasma and urine will be provided. A comparison between MEPS and other extraction techniques such as SPE, LLE, SPME and SBSE will be discussed.

  • 6. Abu-Bakr, Sherifa M.
    et al.
    Bassyouni, Fatma A.
    Rehim, Mohamed Abdel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Pharmacological evaluation of benzimidazole derivatives with potential antiviral and antitumor activity2012Inngår i: Research on chemical intermediates (Print), ISSN 0922-6168, E-ISSN 1568-5675, Vol. 38, nr 9, s. 2523-2545Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    In recent years the synthesis of benzimidazole and its derivatives has attracted the attention of many organic chemists because of the compounds' interesting biological activity and the crucial importance of the benzimidazole unit in the function of these biologically important molecules. Benzimidazole-based polyheterocyclic compounds have several interesting biological properties. Simple synthetic strategies leading to benzimidazole-based fused polyheterocyclic systems and the antiviral and anticancer biological activity of the compounds are surveyed in this review article.

  • 7.
    Abuzooda, Thana
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Amini, Ahmad
    Abdel-Rehim, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Graphite-based microextraction by packed sorbent for online extraction of beta-blockers from human plasma samples2015Inngår i: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 992, s. 86-90Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present work a new graphitic material (Carbon-XCOS) was used as a sorbent for microextraction by packed sorbent (MEPS).The beta-blockers metoprolol and acebutolol in plasma samples were extracted and detected online using Carbon-MEPS syringe and liquid chromatography and tandem mass spectrometry (LC-MS/MS). Factors affecting the MEPS performance such as conditioning, washing and elution solutions were investigated. The validation of the bioanalytical method was performed using human plasma. The standard curve ranged from 10 to 2000 nM and the lower limit of quantification (LLOQ) was set to 10 nM. The method validation showed good accuracy and precision for the quality control (QC) samples at three concentration levels (30, 800 and 1600 nM). The accuracy values of the QC samples were in the range of 86-108% (n = 18). The precision values of intra- and inter-day for QC samples ranged from 4.4% to 14.4% (RSD) for the both studied analytes. The coefficient of determination (R-2) values were >= 0.999 (n = 3).

  • 8. Ahlvik, P
    et al.
    Karlsson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM).
    Westerholm, Roger
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Åsman, P
    Exhaust emissions from flexi-fuel light-duty passenger cars fuelled by petrol (E5) and bioethanol (E70, E85) tested at ambient temperatures of +22°C and -7°C: Part 1:Regulated and particulate emissions.2008Inngår i: Proceedings of the17:th International Symposium on Alcohol Fuels, 2008Konferansepaper (Annet vitenskapelig)
  • 9.
    Ahmed, Trifa M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Bergvall, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Åberg, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Westerholm, Roger
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Determination of oxygenated and native polycyclic aromatic hydrocarbons in urban dust and diesel particulate matter standard reference materials using pressurized liquid extraction and LC-GC/MS2015Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 407, nr 2, s. 427-438Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this study was to develop a novel analytical chemistry method, comprised of a coupled high-performance liquid chromatography-gas chromatography/mass spectrometry system (LC-GC/MS) with low detection limits and high selectivity, for the identification and determination of oxygenated polycyclic aromatic hydrocarbons (OPAHs) and polycyclic aromatic hydrocarbons (PAHs) in urban air and diesel particulate matter. The linear range of the four OPAHs, which include 9,10-anthraquinone, 4H-cyclopenta[def]phenanthrene-4-one, benzanthrone, and 7,12-benz[a]anthraquinone, was 0.7 pg-43.3 ng with limits of detection (LODs) and limits of quantification (LOQs) on the order of 0.2-0.8 and 0.7-1.3 pg, respectively. The LODs in this study are generally lower than values reported in the literature, which can be explained by using large-volume injection. The recoveries of the OPAHs spiked onto glass fiber filters using two different pressurized liquid extraction (PLE) methods were in the ranges of 84-107 and 67-110 %, respectively. The analytical protocols were validated using the following National Institute of Standards and Technology standard reference materials: SRM 1649a (Urban Dust), SRM 1650b (Diesel Particulate Matter), and SRM 2975 (Diesel Particulate Matter, Industrial Forklift). The measured mass fractions of the OPAHs in the standard reference materials (SRMs) in this present study are higher than the values from the literature, except for benzanthrone in SRM 1649a (Urban Dust). In addition to the OPAHs, 44 PAHs could be detected and quantified from the same particulate extract used in this protocol. Using data from the literature and applying a two-sided t test at the 5 % level using Bonferroni correction, significant differences were found between the tested PLE methods for individual PAHs. However, the measured mass fractions of the PAHs were comparable, similar to, or higher than those previously reported in the literature.

  • 10.
    Ahmed, Trifa Mohammed
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Lim, Hwanmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Bergvall, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Westerholm, Roger
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Automated clean-up, separation and detection of polycyclic aromatic hydrocarbons in particulate matter extracts from urban dust and diesel standard reference materials using a 2D-LC/2D-GC system2013Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 405, nr 25, s. 8215-8222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A multidimensional, on-line coupled liquid chromatographic/gas chromatographic system was developed for the quantification of polycyclic aromatic hydrocarbons (PAHs). A two-dimensional liquid chromatographic system (2D-liquid chromatography (LC)), with three columns having different selectivities, was connected on-line to a two-dimensional gas chromatographic system (2D-gas chromatography (GC)). Samples were cleaned up by combining normal elution and column back-flush of the LC columns to selectively remove matrix constituents and isolate well-defined, PAH enriched fractions. Using this system, the sequential removal of polar, mono/diaromatic, olefinic and alkane compounds from crude extracts was achieved. The LC/GC coupling was performed using a fused silica transfer line into a programmable temperature vaporizer (PTV) GC injector. Using the PTV in the solvent vent mode, excess solvent was removed and the enriched PAH sample extract was injected into the GC. The 2D-GC setup consisted of two capillary columns with different stationary phase selectivities. Heart-cutting of selected PAH compounds in the first GC column (first dimension) and transfer of these to the second GC column (second dimension) increased the baseline resolutions of closely eluting PAHs. The on-line system was validated using the standard reference materials SRM 1649a (urban dust) and SRM 1975 (diesel particulate extract). The PAH concentrations measured were comparable to the certified values and the fully automated LC/GC system performed the clean-up, separation and detection of PAHs in 16 extracts in less than 24 h. The multidimensional, on-line 2D-LC/2D-GC system eliminated manual handling of the sample extracts and minimised the risk of sample loss and contamination, while increasing accuracy and precision.

  • 11.
    Aldaeus, Fredrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    New Tools for Trapping and Separation in Gas Chromatography and Dielectrophoresis: Improved Performance by Aid of Computer Simulation2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Computer simulations can be useful aids for both developing new analytical methods and enhancing the performance of existing techniques. This thesis is based on studies in which computer simulations were key elements in the development of several new tools for use in gas chromatography and dielectrophoresis. In gas chromatography, gaseous analytes are separated by exploiting differences in their partitioning between different phases, and after their partitioning parameters have been determined the separations can be computationally predicted, and optimized, for a wide range of operating conditions. Similarly, in dielectrophoresis, particles with differing polarizability or size can be separated, and since particle trajectories within a separation device can be predicted using computations, the suitability of new designs, applications of forces and combinations of operational parameters can be assessed without necessarily making or empirically testing all of the variants.

    Using two existing numerical methods combined with semi-empirical determinations of retention behavior, temperature-programmed gas chromatograms were predicted with less than one percent deviations from experimental data, and a new method for improving the capacity of a gas-trapping device was predicted and experimentally verified. In addition, two new concepts with potential capacity to enhance dielectrophoretic separations were developed and tested in simulations. The first provides a promising way to improve the trapping of bacteria in media with elevated conductivity by using super-positioned electric fields, and the second a way to increase selectivity in the separation of bio-particles by using multiple dielectrophoretic cycles. The studies also introduced a more accurate method for determining the conductivity of suspensions of bacteria, and a new computational method for determining the dielectrophoretic behavior of particles in concentrated suspensions.

    The scientific studies are summarized and discussed in the main text of this thesis, and presented in detail in seven appended papers.

  • 12.
    Aldaeus, Fredrik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Lin, Yuan
    Roeraade, Johan
    Amberg, Gustav
    Multi-stepped dielectrophoresis for separation of particles2006Inngår i: Journal of Chromatography A, Vol. 1131, s. 261–266-Artikkel i tidsskrift (Fagfellevurdert)
  • 13.
    Aldaeus, Fredrik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Lin, Yuan
    Roeraade, Johan
    Amberg, Gustav
    Superpositioned dielectrophoresis for enhanced trapping efficiency2005Inngår i: Electrophoresis, Vol. 26, s. 4252–4259-Artikkel i tidsskrift (Fagfellevurdert)
  • 14.
    Aldaeus, Fredrik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Thewalim, Yasar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Colmsjö, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Prediction of retention times and peak widths in temperature-programmed gas chromatography using the finite element method2009Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1216, nr 1, s. 134-139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Optimization of separations in gas chromatography is often a time-consuming task. However, computer simulations of chromatographic experiments may greatly reduce the time required. In this study, the finite element method was used to predict the retention times and peak widths of three analytes eluting from each of four columns during chromatographic separations with two temperature programs. The data acquired were displayed in predicted chromatograms that were then compared to experimentally acquired chromatograms. The differences between the predicted and measured retention times were typically less than 0.1%, although the experimental peak widths were typically 10% larger than expected from the idealized calculations. Input data for the retention and peak dispersion calculations were obtained from isothermal experiments, and converted to thermodynamic parameters.

  • 15.
    Aldaeus, Fredrik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Thewalim, Yasar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Colmsjö, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Prediction of retention times of polycyclic aromatic hydrocarbons and n -alkanes in temperature-programmed gas chromatography2007Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 389, nr 3, s. 941-950Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have developed an iterative procedure for predicting the retention times of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes during separations by temperature-programmed gas chromatography. The procedure is based on estimates of two thermodynamic properties for each analyte (the differences in enthalpy and entropy associated with movements between the stationary and mobile phases) derived from data acquired experimentally in separations under isothermal conditions at temperatures spanning the range covered by the temperature programs in ten-degree increments. The columns used for this purpose were capillary columns containing polydimethylsiloxane-based stationary phases with three degrees of phenyl substitution (0%, 5%, and 50%). Predicted values were mostly within 1% of experimentally determined values, implying that the method is stable and precise.

  • 16.
    Aldaeus, Fredrik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Thewalim, Yasar
    Colmsjö, Anders
    Prediction of temperature-programmed gas chromatograms using the finite element methodArtikkel i tidsskrift (Fagfellevurdert)
  • 17.
    Alm, Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Solving the correspondence problem in analytical chemistry: Automated methods for alignment and quantification of multiple signals2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    When applying statistical data analysis techniques to analytical chemical data, all variables must have correspondence over the samples dimension in order for the analysis to generate meaningful results. Peak shifts in NMR and chromatography destroys that correspondence and creates data matrices that have to be aligned before analysis. In this thesis, new methods are introduced that allow for automated transformation from unaligned raw data to aligned data matrices where each column corresponds to a unique signal. These methods are based around linear multivariate models for the peak shifts and Hough transform for establishing the parameters of these linear models. Methods for quantification under difficult conditions, such as crowded spectral regions, noisy data and unknown peak identities are also introduced. These methods include automated peak selection and a robust method for background subtraction. This thesis focuses on the processing of the data; the experimental work is secondary and is not discussed in great detail.

    All the developed methods are put together in a full procedure that takes us from raw data to a table of concentrations in a matter of minutes.

    The procedure is applied to 1H-NMR data from biological samples, which is one of the toughest alignment tasks available in the field of analytical chemistry. It is shown that the procedure performs consistently on the same level as much more labor intensive manual techniques such as Chenomx NMRSuite spectral profiling.

    Several kinds of datasets are evaluated using the procedure. Most of the data is from the field of Metabolomics, where the goal is to establish concentrations of as many small molecules as possible in biological samples.

  • 18.
    Alm, Erik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Bro, Rasmus
    Engelsen, Sören B.
    Karlberg, Bo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Torgrip, Ralf J. O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Vibrational overtone combination spectroscopy (VOCSY)—a new way of using IR and NIR data2007Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 388, nr 1, s. 179-188Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work explores a novel method for rearranging 1st order (one-way) infra-red (IR) and/or near infra-red (NIR) ordinary spectra into a representation suitable for multi-way modelling and analysis. The method is based on the fact that the fundamental IR absorption and the first, second, and consecutive overtones of NIR absorptions represent identical chemical information. It is therefore possible to rearrange these overtone regions of the vectors comprising an IR and NIR spectrum into a matrix where the fundamental, 1st, 2nd, and consecutive overtones of the spectrum are arranged as either rows or columns in a matrix, resulting in a true three-way tensor of data for several samples. This tensorization facilitates explorative analysis and modelling with multi-way methods, for example parallel factor analysis (PARAFAC), N-way partial least squares (N-PLS), and Tucker models. The vibrational overtone combination spectroscopy (VOCSY) arrangement is shown to benefit from the “order advantage”, producing more robust, stable, and interpretable models than, for example, the traditional PLS modelling method. The proposed method also opens the field of NIR for true peak decomposition—a feature unique to the method because the latent factors acquired using PARAFAC can represent pure spectral components whereas latent factors in principal component analysis (PCA) and PLS usually do not.

  • 19.
    Alm, Erik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Csenki, Leonard
    Torgrip, Ralf J.O.
    Åberg, K. Magnus
    Nord, Lars I.
    Schuppe-Koistinen, Ina
    Lindberg, Johan
    Alignment of 1H-NMR data using a Generalized Fuzzy Hough Transform2007Inngår i: SSC10 Conference, Lappeenranta, 2007 and Metabolomics Society 3rd Annual Conference, 2007, 2007Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 20.
    Alm, Erik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Slagbrand, Tove
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Åberg, K. Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Wahlström, Erik
    AstraZeneca R&D Sodertalje, Safety Assessment, Mol Toxicol, S-15185 Sodertalje, Sweden .
    Gustafsson, Ingela
    AstraZeneca R&D Sodertalje, Safety Assessment, Mol Toxicol, S-15185 Sodertalje, Sweden .
    Lindberg, Johan
    AstraZeneca R&D Sodertalje, Safety Assessment, Mol Toxicol, S-15185 Sodertalje, Sweden .
    Automated annotation and quantification of metabolites in (1)H NMR data of biological origin2012Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 403, nr 2, s. 443-455Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In 1H NMR metabolomic datasets, there are often over a thousand peaks per spectrum, many of which change position drastically between samples. Automatic alignment, annotation, and quantification of all the metabolites of interest in such datasets have not been feasible. In this work we propose a fully automated annotation and quantification procedure which requires annotation of metabolites only in a single spectrum. The reference database built from that single spectrum can be used for any number of 1H NMR datasets with a similar matrix. The procedure is based on the generalized fuzzy Hough transform (GFHT) for alignment and on Principal-components analysis (PCA) for peak selection and quantification. We show that we can establish quantities of 21 metabolites in several 1H NMR datasets and that the procedure is extendable to include any number of metabolites that can be identified in a single spectrum. The procedure speeds up the quantification of previously known metabolites and also returns a table containing the intensities and locations of all the peaks that were found and aligned but not assigned to a known metabolite. This enables both biopattern analysis of known metabolites and data mining for new potential biomarkers among the unknowns.

  • 21.
    Alm, Erik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Torgrip, Ralf J. O.
    Åberg, K. Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Schuppe-Koistinen, Ina
    Lindberg, Johan
    A solution to the 1D NMR alignment problem using an extended generalized fuzzy Hough transform and mode support2009Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 395, nr 1, s. 213-223Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper approaches the problem of intersample peak correspondence in the context of later applying statistical data analysis techniques to 1D 1H-nuclear magnetic resonance (NMR) data. Any data analysis methodology will fail to produce meaningful results if the analyzed data table is not synchronized, i.e., each analyzed variable frequency (Hz) does not originate from the same chemical source throughout the entire dataset. This is typically the case when dealing with NMR data from biological samples. In this paper, we present a new state of the art for solving this problem using the generalized fuzzy Hough transform (GFHT). This paper describes significant improvements since the method was introduced for NMR datasets of plasma in Csenki et al. (Anal Bioanal Chem 389:875-885, 15) and is now capable of synchronizing peaks from more complex datasets such as urine as well as plasma data. We present a novel way of globally modeling peak shifts using principal component analysis, a new algorithm for calculating the transform and an effective peak detection algorithm. The algorithm is applied to two real metabonomic 1H-NMR datasets and the properties of the method are compared to bucketing. We implicitly prove that GFHT establishes the objectively true correspondence. Desirable features of the GFHT are: (1) intersample peak correspondence even if peaks change order on the frequency axis and (2) the method is symmetric with respect to the samples.

  • 22.
    Alm, Erik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Torgrip, Ralf J. O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Åberg, K. Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Schuppe-Koistinen, Ina
    Lindberg, Johan
    Time-resolved biomarker discovery inH-NMR data using generalized fuzzy Hough transform alignment and parallel factor analysis2010Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 396, nr 5, s. 1681-1689Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work addresses the subject of time-series analysis of comprehensive 1H-NMR data of biological origin. One of the problems with toxicological and efficacy studies is the confounding of correlation between the administered drug, its metabolites and the systemic changes in molecular dynamics, i.e., the flux of drug-related molecules correlates with the molecules of system regulation. This correlation poses a problem for biomarker mining since this confounding must be untangled in order to separate true biomarker molecules from dose-related molecules. One way of achieving this goal is to perform pharmacokinetic analysis. The difference in pharmacokinetic time profiles of different molecules can aid in the elucidation of the origin of the dynamics, this can even be achieved regardless of whether the identity of the molecule is known or not. This mode of analysis is the basis for metabonomic studies of toxicology and efficacy. One major problem concerning the analysis of 1H-NMR data generated from metabonomic studies is that of the peak positional variation and of peak overlap. These phenomena induce variance in the data, obscuring the true information content and are hence unwanted but hard to avoid. Here, we show that by using the generalized fuzzy Hough transform spectral alignment, variable selection, and parallel factor analysis, we can solve both the alignment and the confounding problem stated above. Using the outlined method, several different temporal concentration profiles can be resolved and the majority of the studied molecules and their respective fluxes can be attributed to these resolved kinetic profiles. The resolved time profiles hereby simplifies finding true biomarkers and bio-patterns for early detection of biological conditions as well as providing more detailed information about the studied biological system. The presented method represents a significant step forward in time-series analysis of biological 1H-NMR data as it provides almost full automation of the whole data analysis process and is able to analyze over 800 unique features per sample. The method is demonstrated using a 1H-NMR rat urine dataset from a toxicology study and is compared with a classical approach: COW alignment followed by bucketing.

  • 23.
    Amini, Nahid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Novel Solid Phase Extraction and Mass Spectrometry Approaches to Multicomponent Analyses in Complex Matrices2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Analysis of compounds present in complex matrices is always a challenge, which can be partly overcome by applying various sample preparation techniques prior to detection. Ideally, the extraction techniques should be as selective as possible, to minimize the concentration of interfering substances. In addition, results can be improved by efficient chromatographic separation of the sample components. The elimination of interfering substances is especially important when utilizing mass spectrometry (MS) as a detection technique since they influence the ionization yields. It is also important to optimize ionization methods in order to minimize detection limits.

    In the work this thesis is based upon, selective solid phase extraction (SPE) materials, a restricted access material (RAM) and graphitized carbon black (GCB) were employed for clean up and/or pre-concentration of analytes in plasma, urine and agricultural drainage water prior to liquid chromatography/mass spectrometry (LC/MS). Two SPE formats, in which GCB was incorporated in µ-traps and disks, were developed for cleaning up small and large volume samples, respectively. In addition, techniques based on use of sub-2 µm C18 particles at elevated temperatures and a linear ion trap (LIT) mass spectrometer were developed to improve the efficiency of LC separation and sensitivity of detection of 6-formylindolo[3,2-b]carbazole (FICZ) metabolites in human urine.

    It was also found that GCB can serve not only as a SPE sorbent, but also as a valuable surface for surface-assisted laser desorption ionization (SALDI) of small molecules. The dual functionality of GCB was utilized in a combined screening-identification/quantification procedure for fast elimination of negative samples. This may be particularly useful when processing large numbers of samples. SALDI analyses of small molecules was further investigated and improved by employing two kinds of new surfaces: oxidized GCB nanoparticles and silicon nitride.

  • 24.
    Amini, Nahid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Crescenzi, Carlo
    Feasibility of an on-line restricted access material/liquidchromatography/tandem mass spectrometry method in the rapid and sensitive determination of organophosphorustriesters in human blood plasma2003Inngår i: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 795, nr 2, s. 245-256Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A rapid on-line solid phase extraction/liquid chromatography/tandem mass spectrometry (SPE/LC/MS/MS) method usingrestricted access material (RAM) was developed for the simultaneous determination of eight organophosphorus triesters inuntreated human blood plasma. In a process involving column-switching techniques, the analytes were enriched on the RAMcolumn, separated using a C-18 analytical column and detected with LC/MS. Tandem mass spectrometrywas used to characterizeand quantify the analytes. To elucidate the fragmentation pathway of a number of the analytes, MS3 experiments using an iontrap mass spectrometer were performed. The matrix effects associated with using APCI and ESI interfaces were investigated.The recoveries obtained were in the range 60–92% (R.S.D. < 6%), with estimated detection limits between 0.2 and 1.8 ng/mlof plasma, and the total analysis time was 27 min.

  • 25.
    Amini, Nahid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Shariatgorji, Mohammadreza
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Crescenzi, Carlo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Thorsen, Gunnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Screening and Quantification of Pesticides in Water Using a Dual-Function Graphitized Carbon Black Disk (Addition/Correction)2011Inngår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 83, s. 631-631Artikkel i tidsskrift (Fagfellevurdert)
  • 26.
    Amini, Nahid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Shariatgorji, Mohammadreza
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Crescenzi, Carlo
    Thorsén, Gunnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Screening and Quantification of Pesticides in Water Using a Dual-Function Graphitized Carbon Black Disk2010Inngår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 82, nr 1, s. 290-296Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simple platform for combining solid phase extraction (SPE) and surface-assisted laser desorption ionization mass spectrometry (SALDI-MS) of extracted analytes, using disks prepared by embedding graphitized carbon black (GCB-4) particles in a network of polytetrafluoroethylene (PTFE), is presented. The system provides a convenient approach for rapid SALDI-MS screening of substances in aqueous samples, which can be followed by robust quantitative and/or structural analyses by liquid chromatography (LC)/MS/MS of positive samples. The extraction discs are easily transferred between gaskets where the sample extraction and desorption of selected samples is performed and the mass spectrometer. The SPE and SALDI properties of the new GCB-4 disc have been characterized for 15 pesticides with varying chemical properties, and the screening strategy has been applied to the analysis of pesticides in agricultural drainage water. Atrazine and atrazine-desethyl-2-hydroxy were detected in the sampled water by SALDI-MS screening and subsequently confirmed and quantified using LC/MS/MS.

  • 27.
    Amini, Nahid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Shariatgorji, Mohammadreza
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Thorsen, Gunnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    SALDI-MS Signal Enhancement Using Oxidized Graphitized Carbon Black Nanoparticles2009Inngår i: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 20, nr 6, s. 1207-1213Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The signal intensity of low-molecular-weight compounds analyzed using surface-assisted laserdesorption/ionization time-of-flight mass spectrometry (SALDI-TOF-MS) was significantlyenhanced when oxidized graphitized carbon black (GCB) particles were used as the desorption/ionization surface. The surface of oxidized GCB contains more carboxylic acid groupsthan non-oxidized GCB. Carboxylic acid groups enhance the efficiency of the ionizationprocess and the desorption of more hydrophobic compounds. A common pharmaceuticalcompound, propranolol, was successfully extracted from Baltic Sea blue mussels and quantifiedusing oxidized GCB as the SALDI surface, whereas deuterated propranolol was used asthe internal standard. The calibration curve showed a wide linear dynamic range of response(0.1–20 g/mL) and good reproducibility (RSD 10%). It was not possible to detectpropranolol in Baltic Sea blue mussels when non-oxidized GCB was used as the SALDI surface.

  • 28. Aminlashgari, Nina
    et al.
    Shariatgorji, Mohammadreza
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Ilag, Leopold L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Hakkarainen, Minna
    Nanocomposites as novel surfaces for laser desorption ionization mass spectrometry2011Inngår i: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 3, nr 1, s. 192-197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possibility to utilize nanocomposite films as easy-to-handle surfaces for surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) of small molecules, such as pharmaceutical compounds, was evaluated. The signal-to-noise values of acebutolol, propranolol and carbamazepine obtained on the nanocomposite surfaces were higher than the values obtained on plain PLA surface showing that the nanoparticles participate in the ionization/desorption process even when they are immobilized in the polymer matrix. The advantages of nanocomposite films compared to the free nanoparticles used in earlier studies are the ease of handling and reduction of instrument contamination since the particles are immobilized into the polymer matrix. Eight inorganic nanoparticles, titanium dioxide, silicon dioxide, magnesium oxide, hydroxyapatite, montmorillonite nanoclay, halloysite nanoclay, silicon nitride and graphitized carbon black at different concentrations were solution casted to films with polylactide (PLA). There were large differences in signal intensities depending on the type of drug, type of nanoparticle and the concentration of nanoparticles. Polylactide with 10% titanium oxide or 10% silicon nitride functioned best as SALDI-MS surfaces. The limit of detection (LOD) for the study was ranging from 1.7 ppm up to 56.3 ppm and the signal to noise relative standard deviations for the surface containing 10% silicon nitride was approximately 20-30%. Scanning electron microscopy demonstrated in most cases a good distribution of the nanoparticles in the polymer matrix and contact angle measurements showed increasing hydrophobicity when the nanoparticle concentration was increased, which could influence the desorption and ionization. Overall, the results show that nanocomposite films have potential as surfaces for SALDI-MS analysis of small molecules.

  • 29. Andersson, Lars. I
    et al.
    Hardenborg, Emilia
    Sandberg-Ställ, Maria
    Möller, Kristina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Henriksson, Johan
    Bramsby-Sjöström, Inger
    Olsson, Lars-Inge
    Abdel-Rehim, Mohamed
    Development of a molecularly imprinted polymer based solid-phase extraction of a local anaesthetics from human plasma2004Inngår i: Analytica Chimica Acta, ISSN 0003-2670, Vol. 526, nr 2, s. 147-154Artikkel i tidsskrift (Fagfellevurdert)
  • 30. Andersson, P
    et al.
    Jesson, G
    Kylberg, G
    Ekstrand, G
    Thorsén, G
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Parallel nanoliter microfluidic analysis system2007Inngår i: Anal Chem, Vol. 79, s. 4022-4030Artikkel i tidsskrift (Fagfellevurdert)
  • 31. Ashri, Nadia Y.
    et al.
    Abdel-Rehim, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Sample treatment based on extraction techniques in biological matrices2011Inngår i: Bioanalysis, ISSN 1757-6180, E-ISSN 1757-6199, Vol. 3, nr 17, s. 2003-2018Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The importance of sample preparation methods as the first stage in bioanalysis is described. In this article, the sample preparation concept and strategies will be discussed, along with the requirements for good sample preparation. The most widely used sample preparation methods in the pharmaceutical industry are presented; for example, the need for same-day rotation of results from large numbers of biological samples in pharmaceutical industry makes high throughput bioanalysis more essential. In this article, high-throughput sample preparation techniques are presented; examples are given of the extraction and concentration of analytes from biological matrices, including protein precipitation, solid-phase extraction, liquid-liquid extraction and microextraction-related techniques. Finally, the potential role of selective extraction methods, including molecular imprinted phases, is considered.

  • 32.
    Ashri, Nadia Y.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Daryanavard, Mosayeb
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Abdel-Rehim, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    micMicroextraction by packed sorbent and liquid chromatography-tandem mass spectrometry as a tool for quantification of peptides in plasma samples: determination of sensory neuron-specific receptors agonist BAM8-22 and antagonist BAM22-8 in plasma samples2013Inngår i: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 27, nr 3, s. 396-403Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microextraction by packed sorbent (MEPS) is a miniaturized, solid-phase extraction (SPE) technique that works online with gas chromatography (GC) and liquid chromatography (LC). Not only is the automation process with MEPS advantageous, but the much smaller volumes of the samples, solvents and dead space in the system also provide other significant advantages such as the speed and the simplicity of the sample preparation process. In this study MEPS has been evaluated for quantification of sensory neuron-specific receptors agonist (BAM8-22). Owing to the instability of BAMs, the focus was on fast extraction and determination of the peptide online using LC-MS/MS. Sorbents such as C2, C8 and ENV+ (hydroxylated polystyrenedivinylbenzene copolymer) were investigated in the present study. MEPS-C8 gave the best results compared with C2 and ENV and it was used for the method validation. The calibration curve was obtained within the concentration range of 20.03045nmol/L in plasma. The regression correlation coefficients for plasma samples were 0.99 for all runs (n=6). The between-batch accuracy and precision for BAM8-22 ranged from 13 to 2.0% and from 4.0 to 14%, respectively. Additionally, the accuracy and precision for BAM22-8 ranged from 13 to 7.0% and from 3.0 to 12%, respectively. The present method was used for pharmacokinetic studies for BAMs in plasma samples.

  • 33.
    Avagyan, Rozanna
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Sadiktsis, Ioannis
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Bergvall, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Westerholm, Roger
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Tire tread wear particles in ambient air—a previously unknown source of human exposure to the biocide 2-mercaptobenzothiazole2014Inngår i: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 21, nr 19, s. 11580-11586Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Urban particulate matter (PM), asphalt, and tire samples were investigated for their content of benzothiazole and benzothiazole derivates. The purpose of this study was to examine whether wear particles, i.e., tire tread wear or road surface wear, could contribute to atmospheric concentrations of benzothiazole derivatives. Airborne particulate matter (PM10) sampled at a busy street in Stockholm, Sweden, contained on average 17 pg/m3 benzothiazole and 64 pg/m3 2-mercaptobenzothiazole, and the total suspended particulate-associated benzothiazole and 2-mercaptobenzothiazole concentrations were 199 and 591 pg/m3, respectively. This indicates that tire tread wear may be a major source of these benzothiazoles to urban air PM in Stockholm. Furthermore, 2-mercaptobenzothiazole was determined in urban air particulates for the first time in this study, and its presence in inhalable PM10 implies that the human exposure to this biocide is underestimated. This calls for a revision of the risk assessments of 2-mercaptobenzothiazole exposure to humans which currently is limited to occupational exposure.

  • 34.
    Avagyan, Rozanna
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Sadiktsis, Ioannis
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Thorsen, Gunnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Östman, Conny
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Westerholm, Roger
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Determination of benzothiazole and benzotriazole derivates in tire and clothing textile samples by high performance liquid chromatography-electrospray ionization tandem mass spectrometry2013Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1307, s. 119-125Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A high performance liquid chromatography–tandem mass spectrometry method utilizing electrospray ionization in positive and negative mode has been developed for the separation and detection of benzothiazole and benzotriazole derivates. Ultra-sonication assisted solvent extraction of these compounds has also been developed and the overall method demonstrated on a selected clothing textile and an automobile tire sample. Matrix effects and extraction recoveries, as well as linearity and limits of detection have been evaluated. The calibration curves spanned over more than two orders of magnitude with coefficients of correlation R2 > 0.99 and the limits of detection and the limits of quantification were in the range 1.7–58 pg injected and 18–140 pg/g, respectively. The extraction recoveries ranged between 69% and 102% and the matrix effects between 75% and 101%. Benzothiazole and benzotriazole derivates were determined in the textile sample and benzothiazole derivatives determined in the tire sample with good analytical performance.

  • 35.
    Axelsson, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Resin acids in commercial products and the work environment of Swedish wood pellets production: Analytical methodology, occurrence and exposure2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The aims of the work this thesis is based upon were to develop convenient analytical procedures for determining resin acids in biological and environmental matrices, and apply them to enhance understanding of the occurrence, exposure to and uptake by exposed individuals of resin acids. Particular focus has been on the workplace environment of the Swedish wood pellets industry. Sample extraction procedures and high-performance liquid chromatography/electrospray ionisation-mass spectrometry (HPLC/ESI-MS) methodologies were developed for measuring resin acids in dust, skin and urine samples. Chromatographic separation of abietic (AA) and pimaric acid was achieved by using a polar-embedded C12 stationary phase. The HPLC/ESI-MS method avoids undesirable oxidation of AA, which was found to occur during the derivatisation step in the standard MDHS 83/2 gas chromatography/flame ionisation detection (GC/FID) methodology, leading to false observations of both AA and the oxidation product 7-oxodehydroabietic acid (7-OXO). Personal exposures to resin acids in the Swedish wood pellet production industry were found to be lower, on average, than the British Occupational Exposure Limit for rosin (50 µg/m3). The oxidised resin acid 7-OXO, was detected in both dust and skin samples indicating the presence of allergenic resin acids. A correlation between air and post-shift urinary concentrations of dehydroabietic acid (DHAA), and a trend towards an increase in urinary 7-OXO during work shifts, were also observed. Whether the increase in 7-OXO was due to direct uptake or metabolism of other resin acids cannot be concluded from the results. An efficient HPLC/UV methodology with diode-array detection was developed for screening commercial products for rosin that could be used in laboratories lacking mass spectrometers. Very high concentrations of free resin acids were detected in depilatory wax strips using the method.

  • 36.
    Axelsson, Sara
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Eriksson, Kåre
    Department of Occupational and Environmental Medicine, University Hospital of Northern Sweden, Umeå, Sweden.
    Hagström, Katja
    Department of Environmental Science, Örebro University, Örebro.
    Bryngelsson, Ing-Liss
    Nilsson, Ulrika
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    HPLC/neg-ESI-MS determination of resin acids in urine from Swedish wood pellets production plants workers and correlation with air concentrations2012Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650Artikkel i tidsskrift (Fagfellevurdert)
  • 37.
    Axelsson, Sara
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Eriksson, Kåre
    Nilsson, Ulrika
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Determination of resin acids during production of wood pellets-a comparison of HPLC/ESI-MS with the GC/FID MDHS 83/2 method2011Inngår i: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 13, nr 10, s. 2940-2945Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Resin acids are constituents of natural and technical products of widespread use. Exposure is known to cause health effects in the airways and on the skin. Liquid chromatography/positive ion electrospray-mass spectrometry (HPLC/pos ESI-MS) was investigated for determination of 7-oxodehydroabietic (7-OXO), dehydroabietic (DHAA) and abietic acid (AA) in wood dust-containing air samples as a derivatisation-free alternative to the GC/FID HSE method 83/2, developed by the Health and Safety Executive UK. The resin acid 7-OXO was measured as a marker for oxidised resin acids, which are known to be the main contact allergens in colophonium. The found detection limits were 0.42 ng m(-3) for 7-OXO, 5.2 ng m(-3) for DHAA and 9.4 ng m(-3) for AA, respectively, which are considerably lower than with the GC/FID method (24, 115 and 89 ng m(-3)). The two methods correlated well, although consistently and significantly lower concentrations of 7-OXO were detected with LC/MS. The higher concentration of this compound with MDHS 83/2 is suggested to be an artefact from the derivatisation step in the presence of soluble wood dust remains.

  • 38. Banack, Sandra Anne
    et al.
    Metcalf, James S.
    Jiang, Liying
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Craighead, Derek
    Ilag, Leopold L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Cox, Paul Alan
    Cyanobacteria Produce N-(2-Aminoethyl)Glycine, a Backbone for Peptide Nucleic Acids Which May Have Been the First Genetic Molecules for Life on Earth2012Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 11, s. e49043-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Prior to the evolution of DNA-based organisms on earth over 3.5 billion years ago it is hypothesized that RNA was the primary genetic molecule. Before RNA-based organisms arose, peptide nucleic acids may have been used to transmit genetic information by the earliest forms of life on earth. We discovered that cyanobacteria produce N-(2-aminoethyl)glycine (AEG), a backbone for peptide nucleic acids. We detected AEG in axenic strains of cyanobacteria with an average concentration of 1 µg/g. We also detected AEG in environmental samples of cyanobacteria as both a free or weakly bound molecule and a tightly bound form released by acid hydrolysis, at concentrations ranging from not detected to 34 µg/g. The production of AEG by diverse taxa of cyanobacteria suggests that AEG may be a primitive feature which arose early in the evolution of life on earth

  • 39. Barath, Stefan
    et al.
    Mills, Nicholas L.
    Lundbäck, Magnus
    Törnqvist, Håkan
    Lucking, Andrew J.
    Langrish, Jeremy P.
    Söderberg, Stefan
    Boman, Christoffer
    Westerholm, Roger
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Londahl, Jakob
    Donaldson, Ken
    Mudway, Ian S.
    Sandström, Thomas
    Newby, David E.
    Blomberg, Anders
    Impaired vascular function after exposure to diesel exhaust generated at urban transient running conditions2010Inngår i: Particle and fibre toxicology, ISSN 1743-8977, Vol. 7, s. 19-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Traffic emissions including diesel engine exhaust are associated with increased respiratory and cardiovascular morbidity and mortality. Controlled human exposure studies have demonstrated impaired vascular function after inhalation of exhaust generated by a diesel engine under idling conditions. Objectives: To assess the vascular and fibrinolytic effects of exposure to diesel exhaust generated during urban-cycle running conditions that mimic ambient 'real-world' exposures. Methods: In a randomised double-blind crossover study, eighteen healthy male volunteers were exposed to diesel exhaust (approximately 250 mu g/m(3)) or filtered air for one hour during intermittent exercise. Diesel exhaust was generated during the urban part of the standardized European Transient Cycle. Six hours post-exposure, vascular vasomotor and fibrinolytic function was assessed during venous occlusion plethysmography with intra-arterial agonist infusions. Measurements and Main Results: Forearm blood flow increased in a dose-dependent manner with both endothelial-dependent (acetylcholine and bradykinin) and endothelial-independent (sodium nitroprusside and verapamil) vasodilators. Diesel exhaust exposure attenuated the vasodilatation to acetylcholine (P < 0.001), bradykinin (P < 0.05), sodium nitroprusside (P < 0.05) and verapamil (P < 0.001). In addition, the net release of tissue plasminogen activator during bradykinin infusion was impaired following diesel exhaust exposure (P < 0.05). Conclusion: Exposure to diesel exhaust generated under transient running conditions, as a relevant model of urban air pollution, impairs vasomotor function and endogenous fibrinolysis in a similar way as exposure to diesel exhaust generated at idling. This indicates that adverse vascular effects of diesel exhaust inhalation occur over different running conditions with varying exhaust composition and concentrations as well as physicochemical particle properties. Importantly, exposure to diesel exhaust under ETC conditions was also associated with a novel finding of impaired of calcium channel-dependent vasomotor function. This implies that certain cardiovascular endpoints seem to be related to general diesel exhaust properties, whereas the novel calcium flux-related effect may be associated with exhaust properties more specific for the ETC condition, for example a higher content of diesel soot particles along with their adsorbed organic compounds.

  • 40. Bassyouni, Fatma A.
    et al.
    Abu-Baker, Sherifa M.
    Mahmoud, Khaled
    Moharam, Maysa
    El-Nakkady, Sally S.
    Rehim, Mohamed Abdel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Synthesis and biological evaluation of some new triazolo[1,5-a]quinoline derivatives as anticancer and antimicrobial agents2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 46, s. 24131-24141Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study, versatile multifunctional unreported triazolo[1,5-a]quinoline derivatives were prepared. Compounds 1-19 were synthesized by adopting appropriate synthetic routes and were pharmacologically evaluated for their in vitro anticancer activity against human cancer cell lines: hepatocellular liver carcinoma (HEPG2) and Caucasian breast adenocarcinoma (MCF-7), in addition to their antibacterial and antifungal activities. Compound 4 demonstrated strong inhibitory effects against breast cancer (MCF-7), whereas compounds 8 and 19 exhibited moderate activity against breast carcinoma cell line MCF-7. Compounds 16 and 19 gave moderate activity against liver carcinoma cell line HEPG2. The antimicrobial activity of the prepared compounds was tested against bacteria and fungi. Among them, the results of antimicrobial activity indicated that compounds 4, 9, 11, 13, 15, 17, 18 and 19 were the most active compounds. Compound 4 exhibited strong activity against Fusarium sp., whereas compounds 9, 11, 15, 17, 18 and 19 showed high activity against Escherichia coli. More specifically, compound 17 displayed a high inhibitory effect against Bacillus cereus, Escherichia coli and Rhizoctonia sp.

  • 41. Bassyouni, Fatma A.
    et al.
    Abu-Bakr, Sherifa M.
    Hegab, Khaled H.
    El-Eraky, Wafaa
    El Beih, Ahmed A.
    Rehim, Mohamed E. Abdel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Synthesis of new transition metal complexes of 1H-perimidine derivatives having antimicrobial and anti-inflammatory activities2012Inngår i: Research on chemical intermediates (Print), ISSN 0922-6168, E-ISSN 1568-5675, Vol. 38, nr 7, s. 1527-1550Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    New series of 1H-perimidine-2-thiol derivatives and (2-substituted-1H-perimidin-1-yl)ethane-1,2-dione derivatives and their ligands (C24H14N4S2O2) H2L1 and (C26H18N4S2O2) H2L2 have been synthesized with transition metal ions, e.g., Copper (II), Silver (I), Cobalt (II) and Ruthenium (III) were prepared and evaluated for their antimicrobial, analgesic and anti-inflammatory activities. The synthesized compounds and their complexes were characterized by elemental analysis, H-1 NMR, IR, MS, molar conductance, thermal gravimetric analysis and electronic spectra. All results revealed that compounds 3 and 13 exhibited high inhibitory effects against some bacterial strains by the disc diffusion method. On the other hand, compounds 2, 3, 7 and 12 displayed potent anti-inflammatory activity.

  • 42. Bassyouni, Fatma A.
    et al.
    Saleh, Tamer S.
    ElHefnawi, Mahmoud M.
    Abd El-Moez, Sherein I.
    El-Senousy, Waled M.
    Abdel-Rehim, Mohamed E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Synthesis, pharmacological activity evaluation and molecular modeling of new polynuclear heterocyclic compounds containing benzimidazole derivatives2012Inngår i: Archives of pharmacal research, ISSN 0253-6269, E-ISSN 1976-3786, Vol. 35, nr 12, s. 2063-2075Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Novel heterocyclic compounds containing benzimidazole derivatives were synthesized from 2-(1Hbenzimidazol-2-yl) acetonitrile (1) and arylhydrazononitrile derivative 2 was obtained via coupling of 1 with 4-methyl phenyldiazonium salt, which was then reacted with hydroxylamine hydrochloride to give amidooxime derivative 3. This product was cyclized into the corresponding oxadiazole derivative 4 upon reflux in acetic anhydride. Compound 4 was refluxed in DMF in the presence of triethylamine to give the corresponding 5-(1H-benzimidazol-2-yl)-2-p-tolyl-2H-1,2,3-triazol-4-amine 6. Treatment of compound 6 with ethyl chloroformate afforded 2,6-dihydro-2-(4-methylphenyl)-1,2,3-triazolo[4aEuro(3),5aEuro(3)-4',5']pyrimido[1,6-a]benzimidazole-5(4H)-one (8). 1,2-bis(2-cyanomethyl-1H-benzimidazol-1-yl)ethane-1,2-dione (10) was synthesized via the condensation reaction of 2-(1H-benzimidazol-2-yl) acetonitrile (1) and diethyloxalate. The reactivity of compound 10 towards some diamine reagents was studied. The in vitro antimicrobial activity of the synthesized compounds was investigated against several pathogenic bacterial strains such as Escherichia coli O157, Salmonella typhimurium, E. coli O119, S. paratyphi, Pseudomonas aeruginosa, Staphylococcus aureus, Listeria monocytogenes and Bacillus cereus. The results of MIC revealed that compounds 12a-c showed the most effective antimicrobial activity against tested strains. On the other hand, compounds 12a, b exhibited high activity against rotavirus Wa strain while compounds 12b, c exhibited high activity against adenovirus type 7. In silico target prediction, docking and validation of the compounds 12a-c were performed. The dialkylglycine decarboxylase bacterial enzyme was predicted as a potential bacterial target receptor using pharmacophorebased correspondence with previous leads; giving the highest normalized scores and a high correlation docking score with mean inhibition concentrations. A novel binding mechanism was predicted after docking using the MOE software and its validation.

  • 43. Bassyouni, Fatma
    et al.
    ElHalwany, Noha
    Abdel-Rehim, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Munir, Neyfeh
    Advances and new technologies applied in controlled drug delivery system2015Inngår i: Research on chemical intermediates (Print), ISSN 0922-6168, E-ISSN 1568-5675, Vol. 41, nr 4, s. 2165-2200Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A drug delivery system is defined as a formulation or a device that enables the introduction of a therapeutic substance into the body and improves its efficacy and safety by controlling the rate, time, and place of release of drugs in the body. This process includes the administration of the therapeutic product, the release of the active ingredients by the product, and the subsequent transport of the active ingredients across the biological membranes to the site of action. Drug delivery systems aim to improve patient compliance and convenience, such as, for example, fast-dissolving tablets. One of the most important goals of pharmaceutical science is localizing the pharmacological activity of the drug at the site of action. Drug delivery systems are molecular tools which, without undesired interactions at other sites, target a specific drug receptor. Keeping in view the advantages of the delivery system, rapidly disintegrating dosage forms have been successfully commercialized, and, because of increased patient demand, these dosage forms are expected to become more popular. Modern drug delivery technology has been made possible by advances in polymer science. These advances have resulted in polymers with unique properties. Drug delivery systems are made from a variety of organic and inorganic compounds such as polymers, lipids (liposomes, nanoemulsions, and solid-lipid nanoparticles), self-assembling amphiphilic molecules, dendrimers, and inorganic nanocrystals. In addition, hydrogels are novel delivery systems that have attracted much attention in current pharmaceutical research.

  • 44. Batlle, R
    et al.
    López, P
    Nerín, C
    Crescenzi, C
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Active single-drop microextraction for the determination of gaseous diisocyanates2008Inngår i: Journal Of Chromatography A, Vol. 1185, s. 155-160Artikkel i tidsskrift (Fagfellevurdert)
  • 45.
    Bergh, Caroline
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Organophosphates and phthalates in air and dust from indoor environments: Method development and applied measurements2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Organophosphate and phthalate esters are polymer additives that are frequently found in air and dust in indoor environments. This thesis describes the development and application of air sampling and selective mass spectrometric (MS) determination of these two compound groups. It also describes the sampling and screening of these compounds in indoor air and dust from different environments and the development and evaluation of a method for the extraction and determination of these compounds in indoor dust.

    An air sampling method previously used for air sampling of only organophosphate esters, is here demonstrated to be applicable for simultaneous sampling of both phthalate and organophosphate esters. Selective detection using tandem mass spectrometry (MS/MS) showed good results for simultaneous determination of organophosphate and phthalate esters in air. The high selectivity of this technique was especially advantageous when analyzing dust.

    Comparison of chemical profiles of the organophosphate ester between indoor environments including daycare centers, offices and private homes differed between the types of locations while the phthalate profiles were rather similar. Comparison of concentration levels of these compounds in multi-storey apartment buildings classified as either high or low risk “sick” buildings could not differentiate the two classes of buildings. Further, the studies also points out some potential sources of organophosphate and phthalate esters in these indoor environments.

    In general the levels of phthalate esters were consistently higher than the levels of organophosphate esters both in air and in dust. Phthalate and organophosphate esters were also determined in a dust standard reference material; seventeen of the targeted compounds were quantified out of which ten had not previously been reported for this reference material.

  • 46.
    Bergh, Caroline
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Luongo, Giovanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Wise, Stephen
    Östman, Conny
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Organophosphate and phthalate esters in standard reference material 2585 organic contaminants in house dust2012Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 402, nr 1, s. 51-59Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The levels of 22 phthalate diesters (phthalates) and organophosphate triesters (organophosphates) have been investigated in standard reference material 2585 (SRM 2585) "organic contaminants in house dust." Ultrasonic-assisted solvent extraction and solid-phase extraction on a Florisil adsorbent were used as the extraction and cleanup steps combined with analysis using gas chromatography-tandem mass spectrometry in positive ion chemical ionization mode. Seven phthalates were detected in the concentration range 1-570 mu g/g. Di(2-ethylhexyl) phthalate was the major phthalate present at 570 mu g/g. Ten organophosphates were detected in SRM 2585. Tris(2-butoxyethyl) phosphate was the predominant organophosphate at 82 mu g/g, and nine organophosphates were determined at concentrations ranging from 0.19 to 2.3 mu g/g. Five organophosphates were below the method detection limit, of which two were in level with the procedural blank. The applied extraction and cleanup method was evaluated for the analysis of SRM 2585. The extraction yield was a parts per thousand yen99%, except for tris(2-chloroethyl) phosphate (97%) and diethyl phthalate (98.5%). The problem of calibration curvature is addressed, and it is shown that the use of deuterated standards improves the analysis. The concentrations of ten organophosphate esters were determined in SRM 2585, and seven of these were compared with existing data. To our knowledge, this is the first report of the levels of the seven phthalates esters in SRM 2585 "organic contaminants in house dust.

  • 47.
    Bergh, Caroline
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Torgrip, Ralf
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Emenius, G.
    Östman, Conny
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Organophosphate and phthalate esters in air and settled dust – a multi-location indoor study2011Inngår i: Indoor Air, ISSN 0905-6947, E-ISSN 1600-0668, Vol. 21, nr 1, s. 67-76Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports the abundance in indoor air and dust of eleven organophosphate esters and six phthalate esters. Both groups of these semi-volatile compounds are widely incorporated as additives into plastic materials used in the indoor environment, thus contributing to indoor exposure to industrial chemicals. Thirty sampling sites representing three different indoor environments (private homes, day care centers, and workplaces) in the Stockholm area, Sweden, were selected to obtain representative concentration profiles in both ambient air and settled dust. Eight of the target organophosphate esters and all six phthalate esters were found in both air and dust samples at all locations. The phthalate esters were more abundant than the organophosphate esters, typically ten times higher total concentrations. Especially interesting were the high levels of tributoxyethyl phosphate in the day care centers, the relatively high levels of chlorinated organophosphate esters in the air of workplaces and the overall high levels of diethylhexyl phthalate in dust. The air concentration profiles of the phosphate esters differed significantly between the three indoor environments, whereas the concentration profiles of the phthalate esters as well as their total concentrations were similar. The correlation between concentrations found in air and in dust was found to be weak.

  • 48.
    Bergh, Caroline
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Torgrip, Ralf
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Östman, Conny
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Simultaneous selective detection of organophosphate and phthalate esters using gas chromatography with positive ion chemical ionization tandem mass spectrometry and its application to indoor air and dust2010Inngår i: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 24, nr 19, s. 2859-2867Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A selective and sensitive method for the simultaneous determination of 14 organophosphate and six phthalate esters using gas chromatography (GC) and mass spectrometry (MS) is presented. Both of these compound classes are frequently found in the indoor environment due to their use as bulk additives in numerous polymers, consumer products and building materials. GC/MS utilizing positive ion chemical ionisation (PICI) in selected reaction monitoring (SRM) mode with isobutane as the reagent gas was found to be the best of the tested methods; it proved superior to electron ionisation (EI) in selected ion monitoring (SIM) mode and to PICI using methane as the reagent gas. The method was applied to indoor air samples collected by active air sampling using solid-phase extraction (SPE) cartridges. Organophosphates and phthalates were simultaneously determined with method detection limits (MDLs) in the range of 0.1-47 ng m(-3). For most compounds the MDLs were <= 0.2 ng m(-3), but due to the presence of some of these ubiquitous indoor air pollutants in the blanks, significantly higher MDLs were observed for a few compounds. Finally, the method was also applied in the screening of a much more complex sample matrix, indoor dust.

  • 49.
    Bergh, Caroline
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Åberg, K. Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Svartengren, Magnus
    Emenius, Gunnel
    Östman, Conny
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Organophosphate and phthalate esters in indoor air: a comparison between multi-storey buildings with high and low prevalence of sick building symptoms2011Inngår i: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 13, nr 7, s. 2001-2009Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An extensive study has been conducted of the prevalence of organophosphorous flame retardants/plasticizers and phthalate ester plasticizers in indoor air. The targeted substances were measured in 45 multi-storey apartment buildings in Stockholm, Sweden. The apartment buildings were classified as high or low risk with regard to the reporting of sick building symptoms (SBS) within the project Healthy Sustainable Houses in Stockholm (3H). Air samples were taken from two to four apartments per building (in total 169 apartments) to facilitate comparison within and between buildings. Association with building characteristics have been examined as well as association with specific sources by combining chemical analysis and exploratory uni- and multivariate data analysis. The study contributes to the overall perspective of levels of organophosphate and phthalate ester in indoor air enabling comparison with other studies. The results indicated little or no difference in the concentrations of the target substances between the two risk classifications of the buildings. The differences between the apartments sampled within (inter) buildings were greater than the differences between (intra) buildings. The concentrations measured in air ranged up to 1,200 ng/m3 for organophosphate esters and up to 11,000 ng/m3 for phthalate esters. Results in terms of sources were discerned e.g. PVC flooring is a major source of benzylbutyl phthalate in indoor air.    

  • 50.
    Berglund, Anna-Karin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Spånning, Erika
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Biverståhl, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Maddalo, Gianluca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Tellgren-Roth, Christian
    Mäler, Lena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Glaser, Elzbieta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Dual targeting to Mitochondria and Chloroplasts: Characterization of Thr-tRNA Synthetase Targeting Peptide2009Inngår i: Molecular Plant, ISSN 1674-2052, Vol. 6, nr 2, s. 1298-1309Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a group of proteins that are encoded by a single gene, expressed as a single precursor protein and dually targeted to both mitochondria and chloroplasts using an ambiguous targeting peptide. Sequence analysis of 43 dual targeted proteins in comparison with 385 mitochondrial proteins and 567 chloroplast proteins of Arabidopsis thaliana revealed an overall significant increase in phenylalanines, leucines, and serines and a decrease in acidic amino acids and glycine in dual targeting peptides (dTPs). The N-terminal portion of dTPs has significantly more serines than mTPs. The number of arginines is similar to those in mTPs, but almost twice as high as those in cTPs. We have investigated targeting determinants of the dual targeting peptide of Thr–tRNA synthetase (ThrRS–dTP) studying organellar import of N- and C-terminal deletion constructs of ThrRS–dTP coupled to GFP. These results show that the 23 amino acid long N-terminal portion of ThrRS–dTP is crucial but not sufficient for the organellar import. The C-terminal deletions revealed that the shortest peptide that was capable of conferring dual targeting was 60 amino acids long. We have purified the ThrRS–dTP(2–60) to homogeneity after its expression as a fusion construct with GST followed by CNBr cleavage and ion exchange chromatography. The purified ThrRS–dTP(2–60) inhibited import of pF1β into mitochondria and of pSSU into chloroplasts at μM concentrations showing that dual and organelle-specific proteins use the same organellar import pathways. Furthermore, the CD spectra of ThrRS–dTP(2–60) indicated that the peptide has the propensity for forming α-helical structure in membrane mimetic environments; however, the membrane charge was not important for the amount of induced helical structure. This is the first study in which a dual targeting peptide has been purified and investigated by biochemical and biophysical means.

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