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  • 1.
    Aldaeus, Fredrik
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Thewalim, Yasar
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Prediction of retention times and peak widths in temperature-programmed gas chromatography using the finite element method2009In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1216, no 1, p. 134-139Article in journal (Refereed)
    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.

  • 2.
    Avagyan, Rozanna
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Sadiktsis, Ioannis
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Thorsen, Gunnar
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Östman, Conny
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Determination of benzothiazole and benzotriazole derivates in tire and clothing textile samples by high performance liquid chromatography-electrospray ionization tandem mass spectrometry2013In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1307, p. 119-125Article in journal (Refereed)
    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.

  • 3. Brits, Martin
    et al.
    Gorst-Allman, Peter
    Rohwer, Egmont R.
    De Vos, Jayne
    de Boer, Jacob
    Weiss, Jana M.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Swedish University of Agricultural Sciences, Sweden.
    Comprehensive two-dimensional gas chromatography coupled to high resolution time-of-flight mass spectrometry for screening of organohalogenated compounds in cat hair2018In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1536, p. 151-162Article in journal (Refereed)
    Abstract [en]

    The coupling of comprehensive two-dimensional gas chromatography with high-resolution time of-flight mass spectrometry offers the best separation efficiency combined with accurate mass measurements over a wide mass range. The tremendous power of this screening tool is illustrated by trace qualitative screening analysis of organohalogenated compounds (OHCs) in pet cat hair. Tentative identification was supported by mass spectral database searches and elemental formula prediction from the experimentally determined accurate mass data. This screening approach resulted in the first tentative identification of pentabromoethylbenzene, decabromodiphenyl ethane, hexabromocyclododecane, trisbromoneopentyl alcohol, tris(2-chloroethyl) phosphate and tris(2-chloroisopropyl)phosphate in the South African indoor environment. A total of seventy-two OHCs were identified in the samples and include known flame retardants, such as polybrominated diphenyl ethers, and legacy contaminants such as polychlorinated biphenyls and organochlorine, organophosphorous and pyrethroid pesticides. The results obtained from cat hair indicate that these pets are exposed to complex mixtures of OHCs and the detection of these compounds suggests that non-invasive cat hair samples can be used to model indoor exposure with reference to external deposition of OHCs present in the air and dust surrounding people. Toddlers share the same environment as pet cats and therefore also the same health risks.

  • 4.
    Carrizo, Daniel
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Grimalt, J.O.
    Gas chromatographic-mass spectrometric analysis of polychlorostyrene congener mixtures in sediments, human sera and cord sera2009In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1216, no 30, p. 5723-5729Article in journal (Refereed)
    Abstract [en]

    Complex mixtures of polychlorostyrenes are produced and released into the environment by reaction of chlorine with graphite at high temperatures, e.g. in electrodes. The occurrence of these compounds in the environment or human tissues is often indicative of pollution from electrolytic processes. Combined gas chromatography coupled to electron impact and negative ion chemical ionization mass spectrometry is described here for the analysis of these compounds in sediments, human venous sera and cord sera. This method has allowed a specific congener identification and quantification of the chlorostyrene mixtures present in fluvial sediments polluted by effluents from a chlorine-alkali plant. Besides octachlorostyrene, the mixture of compounds identified involved the six possible heptachlorostyrenes, fifteen hexachlorostyrenes and seven pentachlorostyrenes, having concentrations in the range of 76-16000 ng g(-1) dry weight. In human sera from the Population exposed to airborne emissions from this plant these compounds ranged between 17 and 63 ng L-1 and the distributions were dominated by octachlorostyrene, three heptachlorostyrenes, including beta,beta-2,3,4,5,6-heptachlorostyrene, and alpha-2,3,4,5,6-hexachlorostyrene. Both distribution patterns showed major differences in composition despite the common pollution source that was influencing both types of samples. The method also revealed qualitative differences between maternal and cord sera from the exposed population.

  • 5.
    Elmongy, Hatem
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Damanhour University, Egypt.
    Ahmed, Hytham
    Wahbi, Abdel-Aziz
    Koyi, Hirsh
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Online post-column solvent assisted and direct solvent-assisted electrospray ionization for chiral analysis of propranolol enantiomers in plasma samples2015In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1418, p. 110-118Article in journal (Refereed)
    Abstract [en]

    An Online post-column solvent-assisted ionization (OPSAI) method was developed for enhancing the ionization of the beta-blocker propranolol utilizing normal phase LC-MS/MS. Solvent-assisted electrospray ionization (SAESI) was studied by the introduction of the assistant solvents A: 0.5% Formic acid in Isopropanolol, B: 0.5% Formic acid in lsopropanolol-Water (1:1), and C: 0.5% Formic acid in water into the electrospray ionization chamber using a spray needle. Analyte molecules can be directly ionized by the aid of the assistant solvent spray. Both methods were applied to the chiral separation of propranolol enantiomers using normal phase analysis on cellulose-based chiral column. Interestingly, both methods are easy to handle and offer a wide range of assistant solvents that can be used in order to gain the optimum ionization of the analyte molecules. The both methods considerably improved the analyte signal and the peak area greatly increased. The propranolol average signal-to-noise (S/N) ratio was enhanced from 26 +/- 1 and 42 +/- 1 to 2341 +/- 61 and 1725 +/- 29 for R-propranolol and S-propranolol, respectively, when the post-column solvent method (OPSAI) was used with isopropanol-assistant solvent (A). While in case of solvent-assisted electrospray ionization method (SAESI) signal was enhanced from 26 +/- 1 and 42 +/- 1 to 2223 +/- 72 and 2155 +/- 58 for R-propranolol and S-propranolol, respectively, with water as an assistant solvent. The limit of detection was 10 ng/mL and the method was linear in the range 50-2000 ng/mL. The NPLC-MS method was applied for the determination of propranolol enantiomers in human plasma after microextraction by packed C18 sorbent.

  • 6.
    Elmongy, Hatem
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Masquelier, Michèle
    Ericsson, Magnus
    Development and validation of a UHPLC-HRMS method for the simultaneous determination of the endogenous anabolic androgenic steroids in human serum2020In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1613, article id 460686Article in journal (Refereed)
    Abstract [en]

    Being performance enhancing hormones, endogenous anabolic androgenic steroids (EAAS) are banned from most competitive sports by the World Anti-doping Agency (WADA). In anti-doping control laboratories, routine assays are mainly performed on urine samples of athletes in and out of competitions. Serum constitutes a promising alternative to urine as it is less subjected to manipulation or contamination that may influence the method sensitivity. The simultaneous determination of EAAS including conjugated metabolites using LC-MS is very challenging due to their contradicting chemical behaviors at the ionization interface of the mass spectrometer. This may prejudice their detection or limit the method sensitivity. Herein, we have addressed these challenges and developed a new method for the simultaneous determination of unconjugated, sulphate- and glucuronide-conjugated EAAS (Androsterone, Etiocholanolone, testosterone, epitestosterone, dihydrotestosterone, dehydroepiandrosterone, androstenedione and 17a-hydroxyprogesterone) in human serum using ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS). The use of mass spectrometric detection in full scan mode facilitated the study of the most versatile adducts for detection and quantitation. A solid phase extraction method was developed for the sample preparation prior to analysis. The method limits of quantitation ranged from 0.006 to 7.904 ng/mL and the recoveries ranged from 70.2% to 96.5%. The method calibration was performed in untreated serum representing realistic matrix composition with correlation coeffecients ranged from 0.9859 to 0.9988. Finally, the serum-levels of the investigated steroids were determined in 4 male and 1 female human subjects to provide estimates of baseline levels based on individual values.

  • 7.
    Gonzalez, Nelida J. D.
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Borg-Karlson, Anna-Karin
    Redeby, Johan Pettersson
    Noziere, Barbara
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Krejci, Radovan
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Pei, Yuxin
    Dommen, Josef
    Prevot, Andre S. H.
    New method for resolving the enantiomeric composition of 2-methyltetrols in atmospheric organic aerosols2011In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1218, no 51, p. 9288-9294Article in journal (Refereed)
    Abstract [en]

    In order to facilitate the determination of the primary and secondary origin of atmospheric organic aerosols, a novel method involving chiral capillary gas chromatography coupled with mass spectrometry has been developed and validated. The method was focused on the analysis of 2-methylerythritol and 2-methylthreitol, considered to be tracers of secondary organic aerosols from the oxidation of atmospheric isoprene. The method was validated by performing various tests using authentic standards, including pure enantiomeric standards. The result showed that the analytical method itself does not affect the enantiomeric composition of the samples analyzed. The method was applied on atmospheric aerosols from a boreal forest collected in Aspvreten, Sweden and on laboratory samples obtained from liquid phase oxidation of isoprene and smog chamber experiments. Aerosol samples contained one enantiomer of 2-methylerythritol in significantly larger quantities than the others. In contrast, the liquid-phase oxidation of isoprene and its gas-phase oxidation in the smog chamber produced all enantiomers in equal quantities. The results obtained where the enantiomer fraction, EF, is larger than 0.50 suggest that 2-methyltetrols in atmospheric aerosols may also have biological origin. Information about the differences between enantiomer fractions obtained using this method brings new insights in the area of atmospheric aerosols.

  • 8. Holmgren, Erik
    et al.
    Ek, Stefan
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Extraction of explosives from soil followed by gas chromatography-mass spectrometry analysis with negative chemical ionization2012In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1222, p. 109-115Article in journal (Refereed)
    Abstract [en]

    A new, simple and accurate method for extraction of explosives from soil was developed and validated. The method includes one hour gentle extraction of compounds from soil in acetonitrile:dichloromethane 50:50 at 30 degrees C. Further analysis was made with GC-MS using cool on-column injection and negative chemical ionization. The method increased the recovery of the more volatile products, generated higher accuracy and was extensively time-saving compared to the conventional EPA (US Environmental Protection Agency) 8330 method. Applications are demonstrated on commercial reference materials.

  • 9.
    Iadaresta, Francesco
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Crescenzi, Carlo
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Universita di Salerno, Italy.
    Amini, Ahmad
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Koyi, Hirsh
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Application of graphitic sorbent for online microextraction of drugs in human plasma samples2015In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1422, p. 34-42Article in journal (Refereed)
    Abstract [en]

    In the present work a new sorbent based on graphitized carbon (CarbonX (R) COA) was evaluated in microextraction by packed sorbent (MEPS) for extraction of lidocaine and ropivacaine from human plasma samples. The new graphitic sorbent showed high recoveries of lidocaine and ropivacaine compared to C18 sorbent In the present study the G-MEPS (syringe packed with graphitic sorbent) was connect online with liquid chromatography tandem mass spectrometry (LC-MS/MS). In order to obtain a fast and reliable method different factors affecting MEPS performance were investigated. The extraction efficiency of the graphitic sorbent was compared with silica-based sorbents used in MEPS. The G-MEPS was also evaluated for reuse (50-100 times). The recoveries of lidocaine and ropivacaine from plasma samples were 79% and 82%; respectively. The method was validated according to FDA (Food and Drug Administration) guideline for bioanalytical method validation. Linearity was assessed in the range 5-2000 nmol/L, with coefficient of determination r(2) > 0,995 (n=3) for lidocaine and r(2) > 0.997 (n=3) for ropivacaine. The lower limit of quantification (LLOQ) was 5 nmol/L and the limit of detection (LOD) was 1 nmol/L for studied analytes in plasma samples. For both analytes considered in this study the accuracy values in plasma samples were ranged from 86% to 113%. The Inter-day precisions, expressed as relative standard deviation (%RSD), at three different concentrations (QC-samples) ranged from 8% to 9% for lidocaine, and from 4% to 11% for ropivacaine.

  • 10.
    Jahnke, Annika
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Berger, Urs
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Trace analysis of per- and polyfluorinated alkyl substances in various matrices-how do current methods perform?2009In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1216, no 3, p. 410-21Article in journal (Refereed)
    Abstract [en]

    Per- and polyfluorinated alkyl substances (PFAS) are a group of industrial chemicals, some of which have been produced for over 50 years. Scarcely one decade ago, their ubiquity in wildlife, humans and the global environment was discovered. This urged the need for robust and reliable, yet very sensitive analytical methods allowing for their determination in various matrices. This article reviews the state-of-the-art in trace analysis of ionic and neutral PFAS in humans as well as environmental samples such as wildlife, water, solid matrices and air. Analytical protocols for PFAS determination in food and consumer products are also included. The methods are critically discussed in terms of their advantages, shortcomings, possibilities, limitations, and potential for further development.

  • 11.
    Jahnke, Annika
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Mayer, Philipp
    Department of Environmental Chemistry and Microbiology, National Environmental Research Institute, Aarhus University,.
    Do complex matrices modify the sorptive properties of polydimethylsiloxane (PDMS) for non-polar organic chemicals?2010In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1217, no 29, p. 4765-4770Article in journal (Refereed)
    Abstract [en]

    The partitioning of non-polar analytes into the silicone polydimethylsiloxane (PDMS) is the basis for many analytical approaches such as solid phase microextraction (SPME), stir bar sorptive extraction (SBSE) and environmental passive sampling. Recently, the methods have been applied to increasingly complex sample matrices. The present work investigated the possible effect of complex matrices on the sorptive properties of PDMS. First, SPME fibers with a 30 mu m PDMS coating were immersed in 15 different matrices, including sediment, suspensions of soil and humic substances, mayonnaise, meat, fish, olive oil and fish oil. Second, the surface of the fibers was wiped clean, and together with matrix-free control fibers, they were exposed via headspace to 7 non-polar halogenated organic chemicals in spiked olive oil. The fibers were then solvent-extracted, analyzed, and the ratios of the mean concentrations in the matrix-immersed fibers to the control fibers were determined for all matrices. These ratios ranged from 92% to 112% for the four analytes with the highest analytical precision (i.e. polychlorinated biphenyls (PCBs) 3, 28, 52 and brominated diphenyl ether (BDE) 3), and they ranged from 74% to 133% for the other three compounds (i.e. PCBs 101.105 and gamma-hexachlorocyclohexane (HCH)). We conclude that, for non-polar, hydrophobic chemicals, the sorptive properties of the PDMS were not modified by the diverse investigated media and consequently that PDMS is suited for sampling of these analytes even in highly complex matrices.

  • 12.
    Kierkegaard, Amelie
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    McLachlan, Michael S.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Determination of decamethylcyclopentasiloxane in air using commercial solid phase extraction cartridges2010In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1217, no 21, p. 3557-3560Article in journal (Refereed)
    Abstract [en]

    Decamethylcyclopentasiloxane (D-5), a high production volume chemical used in personal care products. has been designated for regulation in Canada and is under review in the EU because of concerns about its persistence and potential for bioaccumulation in the environment. D-5 is a volatile compound expected to be found primarily in air, but there is little information on atmospheric concentrations due to the lack of sensitive analytical methods. Here a simple and sensitive method to determine D-5 in ambient air is presented. The challenge in the environmental analysis of D-5 is avoiding contamination. Our method is based on the high trapping efficiency of the sorbent [solute ENV+, combined with a comparably high sampling rate. A small amount of sorbent (10 mg) is eluted in a small volume of n-hexane (0.1-0.6 mL). which is injected onto a GC/MS system without further processing. The simplicity of the method enables the use of a field blank for every sample to trace contamination. The method provides low limits of quantification (similar to 0.3 ng/m(3)), good repeatability and limited breakthrough (similar to 1%). By lowering the limit of quantification compared to published work by almost two orders of magnitude, it became possible to quantify D5 in ambient air at locations remote from strong point sources. The concentrations at a rural Swedish site ranged from 0.7 to 8 ng/m(3) over a period of 4 months.

  • 13.
    Kierkegaard, Amelie
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Sellström, Ulla
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    McLachlan, Michael S
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Environmental analysis of higher brominated diphenyl ethers and decabromodiphenyl ethane.2009In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1216, no 3, p. 364-375Article in journal (Refereed)
    Abstract [en]

    Methods for environmental analysis of higher brominated diphenyl ethers (PBDEs), in particular decabromodiphenyl ether (BDE209), and the recently discovered environmental contaminant decabromodiphenyl ethane (deBDethane) are reviewed. The extensive literature on analysis of BDE209 has identified several critical issues, including contamination of the sample, degradation of the analyte during sample preparation and GC analysis, and the selection of appropriate detection methods and surrogate standards. The limited experience with the analysis of deBDethane suggests that there are many commonalities with BDE209. The experience garnered from the analysis of BDE209 over the last 15 years will greatly facilitate progress in the analysis of deBDethane.

  • 14. Kwon, Joseph
    et al.
    Oh, Jeehyun
    Park, Chiyoul
    Cho, Kun
    Kim, Seung Il
    Kim, Soohyun
    Lee, Sunghoon
    Bhak, Jong
    Norling, Birgitta
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Choi, Jejong-Soon
    Systematic cyanobacterial membrane proteome analysis by combining acid hydrolysis and digestive enzymes with nano-liquid chromatography-Fourier transform mass spectrometry2010In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1217, no 3, p. 285-293Article in journal (Refereed)
    Abstract [en]

    The identification of membrane proteins is currently under-represented since the trans-membrane domains of membrane proteins have a hydrophobic property. Membrane proteins have mainly been analyzed by cleaving and identifying exposed hydrophilic domains. We developed the membrane proteomics method for targeting integral membrane proteins by the following sequential process: in-solution acid hydrolysis, reverse phase chromatographic separation, trypsin or chymotrypsin digestion and nano-liquid chromatography-Fourier transform mass spectrometry. When we employed total membrane proteins of Synechocystis sp. PCC 6803, 155 integral membrane proteins out of a predictable 706 were identified in a single application, corresponding to 22% of a genome. The combined methods of acid hydrolysis-trypsin (AT) and acid hydrolysis-chymotrypsin (AC) identified both hydrophilic and hydrophobic domains of integral membrane proteins, respectively. The systematic approach revealed a more concrete data in mapping the repertoire of cyanobacterial membrane and membrane-linked proteome.

  • 15.
    Lavén, M.
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Alsberg, Tomas
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Yu, Y.
    Adolfsson-Erici, Margaretha
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Sun, H.
    Serial mixed-mode cation- and anion-exchange solid-phase extraction for separation of basic, neutral and acidic pharmaceuticals in wastewater and analysis by high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry2009In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1216, no 1, p. 49-62Article in journal (Refereed)
    Abstract [en]

    A novel solid-phase extraction (SPE) method is presented whereby 15 basic, neutral and acidic pharmaceuticals in wastewater were simultaneously extracted and subsequently separated into different fractions. This was achieved using mixed-mode cation- and anion-exchange SPE (Oasis MCX and MAX) in series. Analysis was performed by high-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (HPLC/QTOF-MS). A fast separation was achieved, with all compounds eluting within 6 min, narrow chromatographic peaks, with a peak base width of 6 s on average, and a high mass accuracy of quantified wastewater sample ions, with average mass errors in absolute value of 0.7 mDa or 2.7 ppm. The recovery of the SPE method in the analysis of sewage treatment plant (STP) influent and effluent wastewater was on average 80% and the ion suppression 30%. For less demanding samples Oasis MCX used alone may be an alternative method, although for STP influent waters containing high loads of organic compounds the clean-up achieved using only Oasis MCX was insufficient, leading to unreliable quantitation. Furthermore, serial SPE separation according to molecular charge added an additional degree of analyte confirmation. For quantitation, an approach combining external standard calibration curves, isotopically labelled surrogate standards and single-point standard addition was used. The applicability of the method was demonstrated in the analysis of influent and effluent wastewater from an STP, using small sample volumes (25–50 mL). The effluent wastewater had been subjected to three different treatments; activated sludge, activated sludge followed by ozonation, and a membrane bioreactor (MBR). Ozone treatment proved superior in removal of the analysed pharmaceuticals, while the MBR provided higher removal efficiencies than the activated sludge process.

  • 16.
    Lim, Hwanmi
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Bergvall, Christoffer
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Jarvis, Ian
    Mattsson, Åse
    Dreij, Kristian
    Stenius, Ulla
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Benzo[a]pyrene-specific online high-performance liquid chromatography fractionation of air particulate extracts–A tool for evaluating biological interactions2014In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1355, p. 100-106Article in journal (Refereed)
    Abstract [en]

    Benzo[a]pyrene (B[a]P) is a known human carcinogen and is commonly used as a surrogate for assessing the carcinogenic risk posed by complex mixtures of polycyclic aromatic hydrocarbons (PAHs) present in air particulate matter (PM). However, studies have shown that using B[a]P as a surrogate may underestimate the carcinogenic potential of PAH mixtures, as the risk assessment approach does not consider interaction effects. Thus, toxicological studies using B[a]P to assess its carcinogenic potential in environmentally derived complex mixtures, as opposed to single compound experiments, could improve risk assessment. The intention of the present study was to develop an online HPLC fractionation system for the selective removal of B[a]P from air PM extracts. Two serial pyrenylethyl (PYE) columns enabled selective separation of B[a]P from its isomers and other PAHs as well as a short fractionation cycle of 30 minutes. One run consisted of three collection steps: the first fraction contained PAHs eluting earlier than B[a]P, the second contained B[a]P and the last contained later-eluting PAHs. The selectivity and recovery of the system was investigated using extracts of Stockholm air PM samples. The overall recovery for all PAHs was approximately 80%, and the system proved to be selective, as it removed 94% of B[a]P and less than 3% of benzo[b]fluoranthene from the complex PAH mixture. Exposing human cells to blanks generated by the fractionation system did not induce cytotoxicity or DNA damage signalling. In conclusion, the online HPLC system was selective for B[a]P fractionation whilst minimising run-to-run variation and allowing repeated fractionations for larger samples due to its relatively short run time

  • 17.
    Luongo, Giovanna
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Iadaresta, Francesco
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Moccia, Emanuele
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Östman, Conny
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Crescenzi, Carlo
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. University of Salerno, Italy.
    Determination of aniline and quinoline compounds in textiles2016In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1471, p. 11-18Article in journal (Refereed)
    Abstract [en]

    A simple method for simultaneous determination of twenty-one analytes, belonging to two classes of compounds, aromatic amines and quinolines, is presented. Several of the analytes considered in this study frequently occur in textiles goods on the open market and have been related to allergic contact dermatitis and/or are proven or suspected carcinogens. The method includes an efficient clean-up step using graphitized carbon black (GCB) that simplifies and improves the robustness of the subsequent GC-MS analysis. Briefly, after solvent extraction of the textile sample, the extract is passed through a GCB SPE cartridge that selectively retain dyes and other interfering compounds present in the matrix, producing a clean extract, suitable for GC-MS analysis, is obtained. The method was evaluated by spiking blank textiles with the selected analytes. Method quantification limits (MQL) ranged from 5 to 720 ng/g depending on the analyte. The linear range of the calibration curves ranged over two order magnitude with coefficients of determination (R-2) higher than 0.99. Recoveries ranged from 70 to 92% with RSDs 1.7-14%. The effectiveness of the method was tested on a variety of textile materials samples from different origin. In a pilot explorative survey, 2,6-dichloro-4-nitroaniline was detected in all the analysed clothing samples in concentrations ranging from 1.0 to 576 mu g/g 2,4-dinitroaniline was detected in four of the seven samples with a highest concentration of 305 mu g/g Quinoline was detected in all samples in concentrations ranging from 0.06 to 6.2 mu g/g. (C) 2016 Elsevier B.V. All rights reserved.

  • 18. Moein, Mohammad Mahdi
    et al.
    El-Beqqali, Aziza
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Javanbakht, Mehran
    Karimi, Mohammad
    Akbari-adergani, Behrouz
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    On-line detection of hippuric acid by microextraction with a molecularly-imprinted polysulfone membrane sorbent and liquid chromatography-tandem mass spectrometry2014In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1372, p. 55-62Article in journal (Refereed)
    Abstract [en]

    Destruction of sorbents during consecutive extractions using the microextraction by packed sorbent (MEPS) technique is a serious problem. In MEPS the complex matrix such as plasma and blood can affect the sorbent physical properties and the sorbent can be deteriorated after handling of few samples. To overcome this problem, the surface of a polysulfone membrane (PSM) was modified by a molecularly imprinted sol-gel and utilized for online extraction of a lung cancer biomarker, hippuric acid (HA), in biological matrices. The molecularly imprinted polymer membrane provided fast, sensitive, selective and robust sample preparation method for HA in biological fluids. In addition, MIP membrane could be used for up to 50 extractions without a significant change in extraction recovery. To achieve the best results, the parameters that influenced the extraction efficiency were thoroughly investigated. Moreover, for evaluating the performance of the molecularly imprinted sol-gel membrane (MISM), a non-molecularly imprinted sol-gel membrane (NISM) as a blank was prepared. The limits of detection CLOD) and quantification (LOQ) for HA in both plasma and urine samples were 0.30 nmol L-1 and 1.0 nmol L-1, respectively. Standard calibration curves were obtained over the range of 1-1000 nmol L-1 for HA in plasma and urine samples. The coefficients of determination (R2) were ≥ 0.997. The extraction recoveries of HA from human plasma and urine samples were higher than 91%. The precision values for HA in plasma and urine samples were 2.2-4.8% and 1.1-6.7%, respectively.

  • 19.
    Moein, Mohammad Mahdi
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Jabbar, Dunia
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    A needle extraction utilizing a molecularly imprinted-sol-gel xerogel for on-line microextraction of the lung cancer biomarker bilirubin from plasma and urine samples2014In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1366, p. 15-23Article in journal (Refereed)
    Abstract [en]

    In the present work, a needle trap utilizing a molecularly imprinted sal-gel xerogel was prepared for the on-line microextraction of bilirubin from plasma and urine samples. Each prepared needle could be used for approximately one hundred extractions before it was discarded. Imprinted and non-imprinted sol-gel xerogel were applied for the extraction of bilirubin from plasma and urine samples. The produced molecularly imprinted sol-gel xerogel polymer showed high binding capacity and fast adsorption/desorption kinetics for bilirubin in plasma and urine samples. The adsorption capacity of molecularly imprinted sal-gel xerogel polymer was approximately 60% higher than that of non-imprinted polymer. The effect of the conditioning, washing and elution solvents, pH, extraction time, adsorption capacity and imprinting factor were investigated. The limit of detection and the lower limit of quantification were set to 1.6 and 5 nmol L-1, respectively using plasma or urine samples. The standard calibration curves were obtained within the concentration range of 5-1000 nmol L-1 in both plasma and urine samples. The coefficients of determination values (R-2) were >= 0.998 for all runs. The extraction recovery was approximately 80% for BR in the human plasma and urine samples.

  • 20.
    Moein, Mohammad Mahdi
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Jabbar, Dunia
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    A novel needle trap utilizing molecularly imprinted-sol-gel xerogel for on-line microextraction of lung cancer biomarker bilirubin from plasma and urine samplesIn: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778Article in journal (Refereed)
  • 21.
    Motwani, Hitesh
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    Törnqvist, Margareta
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    Quantitative analysis by liquid chromatography-tandem mass spectrometry of glycidamide using cob(I)alamin trapping method: Validation and application to in vitro metabolism of acrylamideIn: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778Article in journal (Other academic)
  • 22. Motwani, Hitesh V.
    et al.
    Törnqvist, Margareta
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    Quantitative analysis by liquid chromatography-tandem mass spectrometry of glycidamide using the cob(I)alamin trapping method: Validation and application to in vitro metabolism of acrylamide2011In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1218, no 28, p. 4389-4394Article in journal (Refereed)
    Abstract [en]

    Glycidamide (GA) is the epoxy metabolite of acrylamide (AA). A sensitive analytical method for quantitative measurement of GA from in vitro metabolism studies is useful in several contexts, e.g. in studies of enzyme kinetics in different species and factors influencing the metabolism of AA to GA. It is however difficult to analyse compounds like GA, mainly due to their inherent reactivity. In the present study cob(I)alamin {Cbl(I)}, a reduced form of vitamin B(12), was used for trapping of GA. Cbl(I) can react with electrophilic species, such as an epoxide, 10(5) times faster than standard nucleophiles. The trapping of GA by Cbl(I) results in the formation of an alkylcobalamin (GA-Cbl) that was used for quantitative analysis of the epoxide. The alkylcobalamin was analysed by LC-MS/MS using an electrospray ionization source in the positive ion mode. The Cbl(I) method was validated for measurement of GA in liver S9 fractions from human and rat. GA levels down to 0.01 mu M were measured in the S9 fractions, providing a sensitivity that was ca. 100 times higher than that earlier estimated by the Cbl(I) method for measurement of other (e.g. butadiene) epoxides. Compared to current analytical methods for measurement of GA, the Cbl(I) method was 10-100 times more sensitive. The method was applied to quantify GA formed from the metabolism of AA in liver S9 from human and rat.

  • 23.
    Olsson, Petter
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Holmbäck, Jan
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Herslöf, Bengt
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    A single step reversed-phase high performance liquid chromatography separation of polar and non-polar lipids2014In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1369, p. 105-115Article in journal (Refereed)
    Abstract [en]

    This paper reports a simple chromatographic system to separate lipids classes as well as their molecular species. By the use of phenyl coated silica as stationary phase in combination with a simple mobile phase consisting of methanol and water, all tested lipid classes elute within 30min. Furthermore, a method to accurately predict retention times of specific lipid components for this type of chromatography is presented. Common detection systems were used, namely evaporative light scattering detection (ELSD), charged aerosol detection (CAD), electrospray mass spectrometry (ESI-MS), and UV detection.

  • 24.
    Olsson, Petter
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Sadiktsis, Ioannis
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Holmbäck, Jan
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Class separation of lipids and polycyclic aromatic hydrocarbons in normal phase high performance liquid chromatography - A prospect for analysis of aromatics in edible vegetable oils and biodiesel exhaust particulates2014In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1360, p. 39-46Article in journal (Refereed)
    Abstract [en]

    The retention characteristics of the major lipid components in biodiesels and edible oils as well as representative polycyclic aromatic compounds (PAHs) have been investigated on five different normal phase HPLC stationary phases, in order to optimize class separation for an automatized online HPLC cleanup of PAHs prior GC-MS analysis. By stepwise comparison of different hexane/MTBE compositions as mobile phases on cyano-, phenyl-, pentabromobenzyl-, nitrophenyl- and amino- modified silica columns, the capacity and selectivity factors for each analyte and column could be calculated. It was concluded that the most suitable column for backflush isolation of PAHs in biodiesel and edible oil matrices was the pentabromobenzyl-modified silica (PBB). A previously described online HPLC-GC-MS system using the PBB column was then evaluated by qualitative and quantitative analysis of a biodiesel exhaust particulate extract and a vegetable oil reference material. The GC-MS full scan analysis of the biodiesel particulate extract showed that the lipids had been removed from the sample and a fraction containing PAHs and oxygenated derivatives thereof had been isolated. Quantified mass fractions of PAHs of the reference material BCR-458 agreed well for most of the certified PAH mass fractions in the spiked coconut oil reference material.

  • 25.
    Ramzi, Ahmed
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ahmadi, Hamid
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Sadiktsis, Ioannis
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    A two-dimensional non-comprehensive reversed/normal phase high-performance liquid chromatography/tandem mass spectrometry system for determination of limonene and linalool hydroperoxides2018In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1566, p. 102-110Article in journal (Refereed)
    Abstract [en]

    A two-dimensional non-comprehensive high-performance liquid chromatographic (HPLC) system coupled to electrospray ionization tandem mass spectrometry was developed for the determination of skin allergenic hydroperoxides of limonene and linalool. These compounds are some major components behind skin sensitization and contact (skin) allergy to fragrances.

    Fragrance hydroperoxides usually occur in complex compositions, often as constituents of the natural essential oils added to a large number of commercial products. Their similarities to interfering compounds, many with identical elemental composition, make the determination difficult even when using selective detection methods like mass spectrometry. In this work, a first-dimension chromatographic heart-cut isolation of the hydroperoxides on a reversed-phase HPLC system was combined with a second-dimension normal-phase HPLC system for separation of the hydroperoxides. The intersystem transfer was made by trapping the heart-cut fraction on a short graphitized carbon column, exchanging the mobile phase and back-flushing the hydroperoxides into the second dimension.

    Each analysis was performed within 60 min without any pretreatment, except dilution, prior to injection. The obtained instrumental limits of detection (LODs) at a signal-to-noise ratio of 3 were lower than 1.2 ng injected on column and method LODs were below 0.3 ppm. An after-shave product was shown to contain the highest concentrations of the measured hydroperoxides, with 445 ± 23 ppm of total linalool hydroperoxides. This level is likely able to elicit skin reactions in already sensitized individuals.

  • 26. Ruokonen, Suvi-Katriina
    et al.
    Dusa, Filip
    Rantamaki, Antti H.
    Robciuc, Alexandra
    Holma, Paula
    Holopainen, Juha M.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Wiedmer, Susanne K.
    Distribution of local anesthetics between aqueous and liposome phases2017In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1479, p. 194-203Article in journal (Refereed)
    Abstract [en]

    Liposomes were used as biomimetic models in capillary electrokinetic chromatography (EKC) for the determination of distribution constants (K-D) of certain local anesthetics and a commonly used preservative. Synthetic liposomes comprised phosphatidylcholine and phosphatidylglycerol phospholipids with and without cholesterol. In addition, ghost liposomes made from red blood cell (RBC) lipid extracts were used as pseudostationary phase to acquire information on how the liposome composition affects the interactions between anesthetics and liposomes. These results were compared with theoretical distribution coefficients at pH 7.4. In addition to 25 degrees C, the distribution constants were determined at 37 and 42 degrees C to simulate physiological conditions. Moreover, the usability of five electroosmotic flow markers in liposome (LEKC) and micellar EKC (MEKC) was studied. LEKC was proven to be a convenient and fast technique for obtaining data about the distribution constants of local anesthetics between liposome and aqueous phase. RBC liposomes can be utilized for more representative model of cellular membranes, and the results indicate that the distribution constants of the anesthetics are greatly dependent on the used liposome composition and the amount of cholesterol, while the effect of temperature on the distribution constants is less significant.

  • 27.
    Thewalim, Yasar
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Sadiktsis, Ioannis
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Comparing columns for gas chromatography with the two-parameter model for retention prediction2011In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1218, no 31, p. 5305-5310Article in journal (Refereed)
    Abstract [en]

    The retention times of selected compounds in temperature programmed gas chromatography were predicted using a two-parameter model, on the basis of thermodynamic data obtained from isothermal runs on seven capillary columns, primarily substituted with 5% diphenylsiloxane. The scope for using thermodynamic data obtained from isothermal runs on one column to optimize separation on a different column or a different instrument setup was investigated. Additionally, the predictive utility of thermodynamic data obtained using a DB-5 column that had been in use for three years was compared to that of a new column of the same model. It was found that satisfactory separation could be achieved on one capillary column or instrument setup on the basis of thermodynamic data obtained using a different column or instrument set-up.

  • 28.
    Tollbäck, Johanna
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Crescenzi, Carlo
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Dyremark, Eva
    Determination of the flame retardant tetrabromobisphenol A in air samples by liquid chromatography-mass spectrometry.2006In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1104, no 1-2, p. 106-12Article in journal (Refereed)
    Abstract [en]

    An original method based on LC-MS for determination of the flame retardant tetrabromobisphenol A (TBBPA) in air is presented, as an alternative to the traditionally used GC-MS. The soft ionization in LC-MS makes it possible to monitor the intact molecule and to use 13C-labelled TBBPA as an internal surrogate standard, two features that improve both accuracy and precision of the analyses. Comparison of different acquisition modes in electrospray ionization showed that the lowest detections limit, 3.1 pg TBBPA injected, was obtained in SIM monitoring the molecular ions 542.7/544.7. A fragmentation pathway of TBBPA in LC-ESI-MS is suggested. The only sample clean-up steps required are solvent reduction and filtration of the sample extract. Recoveries were 93% at a 30 ng level and 75% at 3 ng. The new method was tested by analyses of air samples collected at a recycling plant for electronic equipment. The amount of TBBPA found was 13.8 ng/m3 with an RSD of 5.9%. Furthermore, it was found that TBBPA in a standard solution could be partially debrominated, if not carefully protected from light during storage.

  • 29.
    Tollbäck, Johanna
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Tamburro, Davide
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Crescenzi, Carlo
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Carlsson, Håkan
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Air sampling with Empore solid phase extraction membranes and online single-channel desorption/liquid chromatography/mass spectrometry analysis: Determination of volatile and semi-volatile organophosphate esters2006In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1129, no 1, p. 1-8Article in journal (Refereed)
    Abstract [en]

    A method for determining organophosphate esters in air samples using C8 Empore solid phase extraction (SPE) membranes has been developed. After the sampling the analytes trapped in the membrane are completely desorbed with methanol, using an extraction cell connected online to the organic modifier channel of a HPLC gradient pump. The addition of water to the mobile phase prior to analytical chromatography ensures that the analytes are refocused and efficiently separated. Sampling with Empore SPE membranes enables the collection of analytes in both the vapour phase and particulate matter. During the air sampling procedure no losses were observed after 24 h of sampling, yielding a total volume of 14.4 m3, even for the most volatile compound used in this investigation (trimethylphosphate). Complete desorption was observed for all the organophosphate esters and recoveries were greater than 95%, with a relative standard deviation of less than 8%. The limits of detection ranged between 0.4 and 19 pg/m3. The effect of particulate matter on the extraction efficiency was investigated in detail by spiking the membranes with reference standard material. It was also found that the SPE membranes could be stored for at least 5 days at room temperature without any evidence of loss. The efficacy of the method was verified using real samples from different common indoor environments. Interestingly, significant quantities of several phosphate esters were found in a NIST standard reference material (urban dust, SRM 1649a).

  • 30.
    Ullah, Shahid
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Alsberg, Tomas
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Berger, Urs
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Simultaneous determination of perfluoroalkyl phosphonates, carboxylates, and sulfonates in drinking water2011In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1218, no 37, p. 6388-6395Article in journal (Refereed)
    Abstract [en]

    A trace analytical method based on high performance liquid chromatography coupled to quadrupole time-of-flight high resolution mass spectrometry was developed for simultaneous determination of perfluoroalkyl phosphonates (PFPAs, carbon chain lengths C6,8,10), perfluoroalkyl carboxylates (PFCAs. C5-12), and perfluoroalkyl sulfonates (PFSAs. C4,6,8,10) in drinking water (tap water). Analytes were enriched on a mixed mode co-polymeric sorbent (C8 + quaternary amine) using solid phase extraction. Chromatographic separation was achieved on a Zorbax Extend C18 reversed phase column using a mobile phase gradient consisting of water, methanol, and acetonitrile containing 2 mM ammonium acetate and 5 mM 1-methyl piperidine. The mass spectrometer was operated in electrospray negative ion mode. Use of 1-methyl piperidine in the mobile phase resulted in a significant increase in instrument sensitivity for PFPAs through improved chromatographic resolution, background suppression, and increased ionization efficiency. Method detection limits for extraction of 500 mL tap water were in the ranges of 0.095-0.17 ng/L, 0.027-0.17 ng/L, and 0.014-0.052 ng/L for PFPAs. PFCAs, and PFSAs, respectively. Whole method recoveries at a spiking level of 0.5 ng/L to 500 mL HPLC grade water were 40-56%, 56-97%, and 55-77% for PFPAs, PFCAs. and PFSAs, respectively. A matrix effect (signal enhancement) was observed in the detection of PFPAs in tap water extracts, leading to calculated recoveries of 249-297% at a 0.5 ng/L spiking level. This effect resulted in an additional improvement of method sensitivity for PFPAs. To compensate for the matrix effect. PFPAs in tap water were quantified using matrix-matched and extracted calibration standards. The method was successfully applied to the analysis of drinking water collected from six European countries. PFPAs were not detected except for perfluorooctyl phosphonate (PFOPA) at close to the detection limit of 0.095 ng/L in two water samples from Amsterdam, the Netherlands. Highest levels were found for perfluorobutane sulfonate (PFBS, 18.8 ng/L) and perfluorooctanoate (PFOA, 8.6 ng/L) in samples from Amsterdam as well as for perfluorooctane sulfonate (PFOS, 8.8 ng/L) in tap water from Stockholm, Sweden.

  • 31.
    Vestergren, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Ullah, Shahid
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Berger, Urs
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    A matrix effect-free method for reliable quantification of perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids at low parts per trillion levels in dietary samples2012In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1237, p. 64-71Article in journal (Refereed)
    Abstract [en]

    In recent exposure modeling studies diet has been identified as the dominant pathway of human exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). However, the paucity of highly sensitive and accurate analytical data to support these studies means that their conclusions are open to question. Here a novel matrix effect-free method is described for ultra-trace analysis of perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids in dietary samples of varied composition. The method employs ion pair extraction of the analytes into methyl tert-butyl ether and subsequent solid phase extraction clean-up on Florisil and graphitized carbon. The target compounds are separated and detected using ultra performance liquid chromatography coupled to tandem mass spectrometry. Special care was taken to avoid procedural blank contamination and potential contamination sources were elucidated. The performance of the method was validated for five different food test matrices including a duplicate diet sample. Method detection limits in the low to sub pg g(-1) range were obtained for all target analytes, which is 5-100 times more sensitive than previously reported for duplicate diet samples. Total method recoveries were consistently between 50 and 80% for all analytes in all tested food matrices and effects of co-extracted matrix constituents on ionization of the target compounds were found to be negligible. The precision of the method (defined as percentage relative standard deviation) at concentrations close to the respective method limits of quantification was <15% for all analytes. Accurate quantification at ultra-trace levels was demonstrated by laboratory control spike experiments. For the first time the presence of long-chain PFCAs in duplicate diet samples is reported. The method presented here can thus support an improved assessment of human exposure from dietary intake for a range of PFCA and PFSA homologues. Re-analysis of duplicate diet samples, which had been analyzed earlier using another analytical methodology, indicated that dietary intake of PFOA and PFOS may previously have been overestimated.

  • 32.
    Wiberg, Kent
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Andersson, Mattias
    Hagman, Anders
    Jacobsson, Sven P.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Peak purity determination with principal component analysis of high-performance liquid chromatography-diode array detection data2004In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1029, no 1-2, p. 13-20Article in journal (Refereed)
    Abstract [en]

    A method is proposed for the determination of chromatographic peak purity by means of principal component analysis (PCA) of high-performance liquid chromatography with diode array detection (HPLC–DAD) data. The method is exemplified with analysis of binary mixtures of lidocaine and prilocaine with different levels of separation. Lidocaine and prilocaine have very similar spectra and the chromatograms used had substantial peak overlap. The samples analysed contained a constant amount of lidocaine and a minor amount of prilocaine (0.02–2 conc.%) and hence the focus was on determining the purity of the lidocaine peak in the presence of much smaller levels of prilocaine. The peak purity determination was made by examination of relative observation residuals, scores and loadings from the PCA decomposition of DAD data over a chromatographic peak. As a reference method, the functions for peak purity analysis in the chromatographic data system used (Chromeleon) were applied. The PCA method showed good results at the same level as the detection limit of baseline-separated prilocaine, outperforming the methods in Chromeleon by a factor of ten. There is a discussion of the interpretation of the result, with some comparisons with evolving factor analysis (EFA). The main advantage of the PCA method for determination of peak purity over methods like EFA lies in its simplicity, short time of calculation and ease of use.

  • 33. Wiedemeier, Daniel
    et al.
    Hilf, Michael
    Smittenberg, Rienk H.
    University of Zürich, Switzerland.
    Haberle, Simon
    Schmidt, Michael
    Improved assessment of pyrogenic carbon quantity and quality in environmental samples by high-performance liquid chromatography2013In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1304, p. 246-250Article in journal (Refereed)
    Abstract [en]

    The analysis of pyrogenic carbon (PyC) in environmental samples is of great interest, e.g. for carbon cycle assessment, (bio-)char characterization and palaeo-environmental or archeological reconstruction. Here, an HPLC method (HPLC) is presented that reproducibly quantifies benzene polycarboxylic acids (BPCA) as molecular markers for PyC in various kinds of environmental samples. It operates at low pH without requiring an organic modifier and was thoroughly tested with PyC reference materials and a peatland core that served as a feasibility and plausibility check. Compared to the established gas chromatography (GC) method, the HPLC method results in higher BPCA quantification reproducibility by showing a significantly smaller coefficient of variation (HPLC: 5%, GC: 16–23%). It works well with small sample amounts, as for instance from sediment cores and aerosol collectors, and requires less sample preparation work than the GC method. Moreover, the here presented HPLC method facilitates 13C and 14C analyses on PyC from environmental samples

1 - 33 of 33
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