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  • 1. Aminlashgari, Nina
    et al.
    Shariatgorji, Mohammadreza
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Hakkarainen, Minna
    Nanocomposites as novel surfaces for laser desorption ionization mass spectrometry2011In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 3, no 1, p. 192-197Article in journal (Refereed)
    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.

  • 2.
    Chen, Changer Long
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Löfstrand, Karin
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Adolfsson-Erici, Margaretha
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    MacLeod, Matthew
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Determination of fragrance ingredients in fish by ultrasound-assisted extraction followed by purge & trap2017In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 9, no 15, p. 2237-2245Article in journal (Refereed)
    Abstract [en]

    Fragrance materials are widely used in household and personal care products in applications that can lead to emissions into the aquatic environment. Assessing the potential of fragrance materials to bioaccumulate in fish in in vivo laboratory studies requires a reliable analytical method for determining the concentrations of chemical substances in fish tissue. Here, we present an analytical method for simultaneously measuring a group of model chemicals that are representative of chemicals found in fragrance materials in rainbow trout. This method involves ultrasound-assisted extraction (UAE) followed by enrichment of the fragrance ingredients using a purge & trap system. Nine fragrance ingredients including semi-volatile and volatile compounds were selected as model substances for method development. Homogenised whole rainbow trout subsamples were spiked with these nine model fragrance ingredients, hexachlorobenzene (HCB) and 2,2',5,5'-tetrachlorobiphenyl (PCB52). The targeted chemicals were extracted from the fish tissue using acetonitrile in an ultrasonic bath; after solvent exchange to hexane, they were extracted into the gas phase by heating the samples and purging with nitrogen and trapped on a solid-phase extraction (SPE) cartridge. Finally, these chemicals were eluted with hexane from the SPE column and analysed using gas chromatography-mass spectrometry (GC-MS). The proposed method has been evaluated for blanks, spiked recoveries and precision, which are all acceptable. We believe that the method presented here is generally applicable for analysis of acid-sensitive volatile and semi-volatile organic chemicals in fish and provides the basis to conduct in vivo bioaccumulation studies of fragrance materials.

  • 3.
    Masala, Silvia
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Rannug, Ulf
    Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Pressurized liquid extraction as an alternative to the Soxhlet extraction procedure stated in the US EPA method TO-13A for the recovery of polycyclic aromatic hydrocarbons adsorbed on polyurethane foam plugs2014In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 6, no 20, p. 8420-8425Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to develop a pressurized liquid extraction (PLE) method as an alternative to the relatively time consuming Soxhlet extraction procedure described in the United States Environmental Protection Agency (US EPA) method TO-13A for the extraction of PAHs adsorbed onto polyurethane foam plugs (PUFs). For this purpose PUF air samples were collected and split into two parts: one part extracted using PLE and the other one using Soxhlet extraction. Comparable PAH concentrations were obtained upon analysis of the extracts showing that the PLE method developed in this work is a more convenient choice than the commonly used Soxhlet extraction technique proposed by US EPA for the determination of PAHs in air samples. In fact, the developed PLE method required shorter assay times (minutes versus hours), less solvent consumption and simpler operational methods. The exhaustiveness of the developed PLE method was evaluated using repeat static extraction cycles, demonstrating an extraction efficiency for the PAHs of greater than 99%. The PLE method was then applied to diesel exhaust and wood smoke PUF samples showing an extraction efficiency for the PAHs of greater than 93% and 96%, respectively. Furthermore, a PLE method for PUF cleaning was developed as well and employed as an alternative to Soxhlet extraction. The PLE methods developed for cleaning and extracting PUFs presented in this work are suitable to be used in mutagenicity studies using the Ames Salmonella assay as no mutagenicity was found in the PLE generated blanks

  • 4.
    Quaranta, Alessandro
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Karlsson, Isabella
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ndreu, Lorena
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Marini, Federico
    Ingelsson, Martin
    Thorsén, Gunnar
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Glycosylation profiling of selected proteins in cerebrospinal fluid from Alzheimer's disease and healthy subjects2019In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 11, no 26, p. 3331-3340Article in journal (Refereed)
    Abstract [en]

    Alteration of glycosylation has been observed in several diseases, such as cancer and neurodegenerative disorders. The study of changes in glycosylation could lead to a better understanding of mechanisms underlying these diseases and to the identification of new biomarkers. In this work the N-linked glycosylation of five target proteins in cerebrospinal fluid (CSF) from Alzheimer's disease (AD) patients and healthy controls have been analyzed for the first time. The investigated proteins, transferrin (TFN), alpha-1-antitrypsin (AAT), C1-inhibitor, immunoglobulin G (IgG), and alpha-1-acid glycoprotein (AGP), were selected based on the availability of VHH antibody fragments and their potential involvement in neurodegenerative and inflammation diseases. AD patients showed alterations in the glycosylation of low abundance proteins, such as C1-inhibitor and alpha-1-acid glycoprotein. These alterations would not have been detected if the glycosylation profile of the total CSF had been analyzed, due to the masking effect of the dominant profiles of high abundance glycoproteins, such as IgG. Information obtained from single proteins was not sufficient to correctly classify the two sample groups; however, by using an advanced multivariate technique a total non-error rate of 72 +/- 3% was obtained. In fact, the corresponding model was able to correctly classify 71 +/- 4% of the healthy subjects and 74 +/- 7% of the AD patients. Even if the results were not conclusive for AD, this approach could be extremely useful for diseases in which glycosylation changes are reported to be more extensive, such as several types of cancer and autoimmune diseases.

  • 5. Zazouli, Mohammad Ali
    et al.
    Akbari-adergani, Behrouz
    Javanbakht, Mehran
    Moein, Mohammad Mahdi
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    On-line extraction and determination of residual sulfathiazole in pharmaceutical wastewater with molecularly imprinted polymers in a packed cartridge coupled with high-performance liquid chromatography2017In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 9, no 20, p. 3019-3028Article in journal (Refereed)
    Abstract [en]

    A new, rapid and sensitive on-line extraction and determination technique was developed with molecularly imprinted polymers (MIPs) in a packed cartridge. An artificial selective polymeric sorbents packed in a polyethylene cartridge were employed for the separation of sulfathiazole residue. The packing particles were synthesized using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker agent, sulfathiazole as a target template molecule and azobisisobutyronitrile as an initiator. The optimal conditions for designing these sorbents were as follows: conditioning using water with pH = 3.0, loading the sample under mild basic aqueous conditions, cleanup using 2 x 2 mL acetonitrile and elution with 3.0 mL 20 mM ammonium acetate : acetonitrile (75 : 25 v/v, pH = 3.0). In this system, an aliquot of extracted template was injected to the HPLC analytical column with acetonitrile : water (75 : 25 v/v) and water (pH adjusted to 3.0 with H3PO4) as the mobile phases in a gradient elution program. The selectivity of the MIPs in the packed cartridge was evaluated by checking several substances with molecular structures similar to that of the template. The results revealed a recovery of more than 92% along with a limit of detection and limit of quantification of 0.05 and 0.16 ng mL(-1), respectively, for the on-line determination of sulfathiazole in pharmaceutical wastewater samples.

  • 6.
    Zurita, Javier
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Zguna, Nadezda
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Andrýs, Rudolf
    Strzelczak, Anna
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Jiang, Liying
    Thorsen, Gunnar
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Chiral separation of beta-Methylamino-alanine (BMAA) enantiomers after (+)-1-(9-fluorenyl)-ethyl chloroformate (FLEC) derivatization and LC-MS/MS2019In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 11, p. 432-442Article in journal (Refereed)
    Abstract [en]

    β-Methylamino-L-alanine, a neurotoxin first isolated from the seeds of cycad tree Cycas circinalis, is widely spread in a variety of environments. New sensitive techniques and robust methodologies are needed to detect its presence in complex biological samples and to further understand its biochemical properties. In this context, the determination of the enantiomeric composition of natural BMAA is of great importance. In this study, a simple and easily implemented LC-ESI-MS/MS method was developed to determine the presence of both D- and L-BMAA enantiomers in samples of cycad seed (Cycas micronesica). The samples were subjected to enzymatic hydrolysis to avoid racemization that occurs during strong acid hydrolysis. Derivatization with (+)-1-(9-fluorenyl)-ethyl chloroformate (FLEC) was performed prior to LC-ESI-MS/MS to produce chromatographically separable derivatives of D- and L-BMAA. Together with the retention time, two MRM transitions and their peak area ratios were used to identify the compounds. The LOQ obtained was 0.3 μg BMAA per g wet weight for each enantiomer. Method repeatability was within 3 RSD% both intraday and interday and accuracy was 98–108%. An accurate enantiomeric composition was obtained from the samples of cycad seed, where L- and D-BMAA were detected at 50.13 ± 0.05 and 4.08 ± 0.04 μg BMAA per g wet weight respectively (n = 3).

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