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  • 1. Alves, Andreia
    et al.
    Giovanoulis, Georgios
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Swedish Environmental Research Institute, Sweden.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Erratico, Claudio
    Lucattini, Luisa
    Haug, Line S.
    Jacobs, Griet
    de Wit, Cynthia A.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Leonards, Pim E. G.
    Covaci, Adrian
    Magner, Jorgen
    Voorspoels, Stefan
    Case Study on Screening Emerging Pollutants in Urine and Nails2017In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, no 7, p. 4046-4053Article in journal (Refereed)
    Abstract [en]

    Alternative plasticizers and flame retardants (FRs) have been introduced as replacements for banned or restricted chemicals, but much is still unknown about their metabolism and occurrence in humans. We identified the metabolites formed in vitro for four alternative plasticizers (acetyltributyl citrate (ATBC), bis(2-propylheptyl) phthalate (DPHP), bis(2-ethylhexyl) terephthalate (DEHTP), bis(2ethylhexyl) adipate (DEHA)), and one FR (2,2-bis (chloromethyl)-propane-1,3-diyltetrakis(2-chloroethyl) bisphosphate (V6)). Further, these compounds and their metabolites were investigated by LC/ESI-Orbitrap-MS in urine and finger nails collected from a Norwegian cohort. Primary and secondary ATBC metabolites had detection frequencies (% DF) in finger nails ranging from 46 to 95%. V6 was identified for the first time in finger nails, suggesting that this matrix may also indicate past exposure to FRs as well as alternative plasticizers. Two isomeric forms of DEHTP primary metabolite were highly detected in urine (97% DF) and identified in finger nails, while no DPHP metabolites were detected in vivo. Primary and secondary DEHA metabolites were identified in both matrices, and the relative proportion of the secondary metabolites was higher in urine than in finger nails; the opposite was observed for the primary metabolites. As many of the metabolites present in in vitro extracts were further identified in vivo in urine and finger nail samples, this suggests that in vitro assays can reliably mimic the in vivo processes. Finger nails may be a useful noninvasive matrix for human biomonitoring of specific organic contaminants, but further validation is needed.

  • 2.
    Axelsson, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    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
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    HPLC/neg-ESI-MS determination of resin acids in urine from Swedish wood pellets production plants workers and correlation with air concentrations2012In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650Article in journal (Refereed)
  • 3.
    Axelsson, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Eriksson, Kåre
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Determination of resin acids during production of wood pellets-a comparison of HPLC/ESI-MS with the GC/FID MDHS 83/2 method2011In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 13, no 10, p. 2940-2945Article in journal (Refereed)
    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.

  • 4. Bennike, Niels H.
    et al.
    Palangi, Lina
    Bråred Christensson, Johanna
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Zachariae, Claus
    Johansen, Jeanne D.
    Hagvall, Lina
    Allergic contact dermatitis caused by hydroperoxides of limonene and dose-response relationship-A repeated open application test (ROAT) study2019In: Contact Dermatitis, ISSN 0105-1873, E-ISSN 1600-0536, Vol. 80, no 4, p. 208-216Article in journal (Refereed)
    Abstract [en]

    Background: Contact allergy to oxidized limonene, with hydroperoxides of limonene (Lim-OOHs) as the main allergens, is common. However, high proportions of weak positive and doubtful patch test reactions have been reported. Objectives: To determine the clinical relevance, elicitation threshold and dose-response relationship of Lim-OOHs in individuals with a positive or doubtful patch test reaction to standard Lim-OOHs 0.3% pet. Methods: A multicentre 3-week double-blind vehicle-controlled repeated open application test (ROAT) study with a simulated fine fragrance containing Lim-OOHs at 1260, 420 and 140 ppm, equal to a dose/area per application of Lim-OOHs of 3.0, 0.99 and 0.33 mu g/cm(2), was performed. Results: Among 11 subjects allergic to Lim-OOHs, 11 (100%), 7 (64%), and 3 (27%), respectively, reacted to the applied doses. No reactions were seen in 17 healthy controls exposed to the highest dose. This difference in reactivity was statistically significant (P < 0.0001). Among 13 subjects with doubtful patch test reactions to Lim-OOHs, two (15%) had positive ROAT reactions to the highest Lim-OOH dose applied (P = 0.36 as compared with controls). Conclusions: Contact allergy to Lim-OOHs is of clinical relevance in patients with positive patch test reactions. A doubtful patch test reaction to Lim-OOHs 0.3% pet. can be of clinical relevance.

  • 5.
    Carlsson, Henrik
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    von Stedingk, Hans
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Törnqvist, Margareta
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    LC–MS/MS Screening Strategy for Unknown Adducts to N-Terminal Valine in Hemoglobin Applied to Smokers and Nonsmokers2014In: Chemical Research in Toxicology, ISSN 0893-228X, E-ISSN 1520-5010, Vol. 27, no 12, p. 2062-2070Article in journal (Refereed)
    Abstract [en]

    Electrophilically reactive compounds have the ability to form adducts with nucleophilic sites in DNA and proteins, constituting a risk for toxic effects. Mass spectrometric detection of adducts to N-terminal valine in hemoglobin (Hb) after detachment by modified Edman degradation procedures is one approach for in vivo monitoring of exposure to electrophilic compounds/metabolites. So far, applications have been limited to one or a few selected reactive species, such as acrylamide and its metabolite glycidamide. This article presents a novel screening strategy for unknown Hb adducts to be used as a basis for an adductomic approach. The method is based on a modified Edman procedure, FIRE, specifically developed for LC-MS/MS analysis of N-terminal valine adducts in Hb detached as fluorescein thiohydantoin (FTH) derivatives. The aim is to detect and identify a priori unknown Hb adducts in human blood samples. Screening of valine adducts was performed by stepwise scanning of precursor ions in small mass increments, monitoring four fragments common for the FTH derivative of valine with different N-substitutions in the multiple-reaction mode, covering a mass range of 135 Da (m/z 503-638). Samples from six smokers and six nonsmokers were analyzed. Control experiments were performed to compare these results with known adducts and to check for artifactual formation of adducts. In all samples of smokers and nonsmokers, seven adducts were identified, of which six have previously been studied. Nineteen unknown adducts were observed, and 14 of those exhibited fragmentation patterns similar to earlier studied FTH derivatives of adducts to valine. Identification of the unknown adducts will be the focus of future work. The presented methodology is a promising screening tool using Hb adducts to indicate exposure to potentially toxic electrophilic compounds and metabolites.

  • 6.
    Carlsson, Josefine
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Iadaresta, Francesco
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Eklund, Jonas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Avagyan, Rozanna
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Östman, Conny
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Suspect and non-target screening of chemicals in clothing textiles by reversed-phase liquid chromatography/hybrid quadrupole-Orbitrap mass spectrometry2021In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 414, no 3, p. 1403-1413Article in journal (Refereed)
    Abstract [en]

    The global manufacturing of clothing is usually composed of multistep processes, which include a large number of chemicals. However, there is generally no information regarding the chemical content remaining in the finished clothes. Clothes in close and prolonged skin contact may thus be a significant source of daily human exposure to hazardous compounds depending on their ability to migrate from the textiles and be absorbed by the skin. In the present study, twenty-four imported garments on the Swedish market were investigated with respect to their content of organic compounds, using a screening workflow. Reversed-phase liquid chromatography coupled to electrospray ionization/high-resolution mass spectrometry was used for both suspect and non-target screening. The most frequently detected compound was benzothiazole followed by quinoline. Nitroanilines with suspected mutagenic and possible skin sensitization properties, and quinoline, a carcinogenic compound, were among the compounds occurring at the highest concentrations. In some garments, the level of quinoline was estimated to be close to or higher than 50,000 ng/g, the limit set by the REACH regulation. Other detected compounds were acridine, benzotriazoles, benzothiazoles, phthalates, nitrophenols, and organophosphates. Several of the identified compounds have logP and molecular weight values enabling skin uptake. This pilot study indicates which chemicals and compound classes should be prioritized for future quantitative surveys and control of the chemical content in clothing as well as research on skin transfer, skin absorption, and systemic exposure. The results also show that the current control and prevention from chemicals in imported garments on the Swedish market is insufficient.

  • 7.
    Carlsson, Josefine
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Åström, Tim
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Östman, Conny
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Disperse azo dyes, arylamines and halogenated dinitrobenzene compounds in synthetic garments on the Swedish market2022In: Contact Dermatitis, ISSN 0105-1873, E-ISSN 1600-0536, Vol. 87, no 4, p. 315-324Article in journal (Refereed)
    Abstract [en]

    Background: Azobenzene disperse dyes (azo DDs) are well-known as textile allergens, but the knowledge of their occurrence in garments is low. The numerous azo DDs and dye components found in textiles constitute a potential health risk, but only seven azo DDs are included in the European baseline patch test series (EBS).

    Objectives: To investigate non-regulated azo DDs and dye components in synthetic garments on the Swedish market.

    Methods: High-performance liquid chromatography/mass spectrometry, gas chromatography/mass spectrometry and computerized data mining.

    Results: Sixty-two azo DDs were detected, with Disperse Red 167:1 occurring in 67%, and 14 other DDs each found in >20% of the garments. Notably, the EBS dyes were less common, three even not detected, while arylamines were frequently detected and exceeded 1 mg/g in several garments. Also, halogenated dinitrobenzenes were identified in 25% of the textiles.

    Conclusion: Azo DDs and dye components, in complex compositions and with large variations, occurred frequently in the synthetic garments. The arylamines were shown to occur at much higher levels compared to the azo DDs, suggesting the former constitute a potentially higher health risk. The role of arylamines and halogenated dinitrobenzenes in textile allergy has to be further investigated.

  • 8.
    Carlsson, Josefine
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Åström, Tim
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Östman, Conny
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Solvent-free automated thermal desorption-gas chromatography/mass spectrometry for direct screening of hazardous compounds in consumer textiles2023In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 415, no 19, p. 4675-4687Article in journal (Refereed)
    Abstract [en]

    The global production of textiles utilizes numerous large-volume chemicals that may remain to some extent in the finished garments. Arylamines, quinolines, and halogenated nitrobenzene compounds are possible mutagens, carcinogens and/or skin sensitizers. For prevention, control of clothing and other textiles must be improved, especially those imported from countries without regulations of textile chemicals. An automated analytical methodology with on-line extraction, separation, and detection would largely simplify screening surveys of hazardous chemicals in textiles. Automated thermal desorption-gas chromatography/mass spectrometry (ATD-GC/MS) was developed and evaluated as a solvent-free, direct chemical analysis for screening of textiles. It requires a minimum of sample handling with a total run time of 38 min including sample desorption, chromatographic separation, and mass spectrometric detection. For most of the studied compounds, method quantification limit (MQL) was below 5 mu g/g for 5 mg of textile sample, which is sufficiently low for screening and control of quinoline and arylamines regulated by EU. Several chemicals were detected and quantified when the ATD-GC/MS method was applied in a limited pilot screening of synthetic fiber garments. A number of arylamines were detected, where some of the halogenated dinitroanilines were found in concentrations up to 300 mu g/g. This is ten times higher than the concentration limit for similar arylamines listed by the EU REACH regulation. Other chemicals detected in the investigated textiles were several quinolines, benzothiazole, naphthalene, and 3,5-dinitrobromobenzene. Based on the present results, we suggest ATD-GC/MS as a screening method for the control of harmful chemicals in clothing garments and other textiles.

  • 9. Clark, Evangéline
    et al.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Samaran, Quentin
    Raison-Peyron, Nadia
    Allergic contact dermatitis from Cannabis sativa (hemp) seed oil2022In: Contact Dermatitis, ISSN 0105-1873, E-ISSN 1600-0536, Vol. 87, no 3, p. 292-293Article in journal (Other academic)
  • 10. Elliott, John F.
    et al.
    Ramzy, Ahmed
    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.
    Moffat, Wayne
    Suzuki, Kunimasa
    Severe intractable eyelid dermatitis probably caused by exposure to hydroperoxides of linalool in a heavily fragranced shampoo2017In: Contact Dermatitis, ISSN 0105-1873, E-ISSN 1600-0536, Vol. 76, no 2, p. 114-115Article in journal (Other academic)
  • 11.
    Gao, Qiuju
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Leck, Caroline
    Stockholm University, Faculty of Science, Department of Meteorology .
    Monosaccharide compositional analysis of marine polysaccharides by hydrophilic interaction liquid chromatography-tandem mass spectrometry2011In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 399, no 7, p. 2517-2529Article in journal (Refereed)
    Abstract [en]

    A simple and sensitive method was developed using hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry for determination of monosaccharides liberated from marine polysaccharides by acidic hydrolysis. Optimal separation of diastereomeric monosaccharides including hexoses, pentoses, and deoxyhexoses was achieved using an aminopropyl bonded column with mobile phase containing ternary solvents (acetonitrile/methanol/water) in conjunction with MS/MS in SRM mode. Mechanisms for fragmentation of deprotonated monosaccharides with regard to cross-ring cleavage were proposed. Matrix effects from coeluting interferences were observed and isotopic-labeled internal standard was used to compensate for the signal suppression. The method demonstrated excellent instrumental limits of detection (LOD), ranging from 0.7 to 4.2 pg. Method LODs range from 0.9 to 5.1 nM. The proposed method was applied to the analysis of polysaccharides in seawater collected from the open leads of the central Arctic Ocean in the summer of 2008.

  • 12.
    Hansson, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Study of mass transfer in a dynamic hollow-fibreliquid phase microextraction system2010In: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 33, no 1, p. 112-119Article in journal (Refereed)
    Abstract [en]

    The extraction characteristics of a dynamic hollow-fibre liquid phase microextractionsystem were investigated by studying the mass transfer and diffusion rates of dinitrophenolsfrom plasma samples over the liquid membrane (dihexylether). The measureddiffusion coefficients were compared with theoretical values calculated from Stokesdiameters. The diffusion mechanism was simulated by computer and the most polarcompounds, 2,4-dinitrophenol and 4,6-o-dinitrocresol, had associated diffusion coefficientsthat were close to the calculated theoretical values. 2-sec-Butyl-4,6 dinitrophenoland 2-tert-butyl-4,6-dinitrophenol, the compounds with the highest log P values, wereretained by the polypropylene membrane, which reduced the experimentally observeddiffusion rates to about half of the theoretical values. The retention was most likely due todispersive forces interacting with the pore inner walls. Extraction was linearly correlatedwith time for all compounds and the repeatability was high (RSDs 7–11%), even for theshortest extraction times. Method LOD as the amount injected ranged between 0.3 and3.1 ng for an extraction cycle of 213 s.

  • 13.
    Hansson, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Karlberg, Bo
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Dynamic hollow-fibre liquid phase microextraction for human plasma samples automated by sequential injection analysisManuscript (preprint) (Other academic)
    Abstract [en]

    This paper presents an easily handled, hollow-fibre liquid phase microextraction (HF-LPME) sample clean-up method, automated by the use of a programmable sequential injection analysis (SIA) system. Use of a SIA system significantly reduces the need for manual sample handling. This new type of clean-up system was assessed and compared with manual HF-LPME for the extraction of acidic compounds (dinitrophenols) from human plasma, in terms of human intervention requirements, efficiency, repeatability and carry-over. Its application to a SIA system for basic compounds (b-blockers) is also presented. The sample aliquots collected off-line from the SIA system were subsequently subjected to separation with LC and the various analytes were detected with ESI-MS.

    Extraction efficiency values between 28 and 56% (RSD 5-10%, n = 7) were achieved for the dinitrophenol compounds after an extraction cycle of 58 min including a 30 min washing step. According to the MS analysis the SIA/HF-LPME method yielded clean chromatograms with no detectable interfering peaks. Ion suppression in positive ESI-MS was between 4 and 21% when tested on extracts with b-blockers.

  • 14.
    Hansson, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Lagerstroem, Malene
    Åberg, Magnus
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Dynamic hollow-fibre liquid phase microextraction of dinitrophenols from human plasma: Optimization of an extraction flow system using experimental design methodology2009In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 79, no 3, p. 633-638Article in journal (Refereed)
    Abstract [en]

    The utility of a dynamic hollow-fibre liquid phase microextraction method (optimized using a four-variable experimental design and response surface modelling) for extracting dinitrophenolic compounds from human plasma samples was evaluated. The investigated variables were donor phase salt concentration (10–400 mM), donor phase pH (2–6), acceptor phase pH (7–12), and donor/acceptor phase flow rates (30/7.5 to 70/17.5 μL min−1). Four dinitrophenol pesticides were used as model substances at concentrations of 0.1 μg mL−1 in spiked human plasma samples. Extraction efficiencies ranging from 42 to 77% with RSDs below 9 were achieved with the optimized method. The flow rate and acceptor pH were shown to strongly affect the extraction efficiency for all compounds, while the donor phase pH and salt concentration had minor effects. With a well-defined acceptor phase pH and flow rate the system exhibited high robustness. The limits of quantification for the investigated compounds, using the presented extraction method followed by liquid chromatography/electrospray ionization mass spectrometry in selected ion monitoring mode, ranged from 0.05 to 0.1 μg mL−1 plasma.

  • 15.
    Hansson, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Assessment of a dynamic hollow-fibre liquid phase microextraction system forhuman blood plasma samples2009In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 77, no 4, p. 1309-1314Article in journal (Refereed)
    Abstract [en]

    A dynamic liquid phase microextraction (LPME) system, based on hollow-fibre supported liquid membrane(SLM) extraction, was developed for extracting ionisable xenobiotics from human plasma, andits performance was evaluated (in terms of extraction efficiency, reproducibility, durability and carryover)using nitrophenolic compounds as model analytes at concentrations of 0.1–0.5gmL−1 in aqueousstandards. The efficiency and repeatability were tested also on spiked human plasma. The system isnon-expensive, convenient, requires minimal manual handling and enables samples with volumes assmall as 0.2mL to be extracted. For plasma samples extraction efficiencies of between 30 and 58% wereachieved within 20 min, including washing steps. The limit of detection (LOD) values were in the range0.02–0.03gmL−1. The developed system can provide enrichment factors up to eight, based on theinjection-to-acceptor volume ratio (in this case 0.2–0.025 mL). The same hollow-fibre membrane wasused up to 8 days with no loss of efficiency. Carry-over was lower than detection limit.

  • 16.
    Isetun, Sindra
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Dynamic field sampling of airborne organophosphate triesters using solid-phase microextraction under equilibrium and non-equilibrium conditions2005In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 30, p. 94-98Article in journal (Refereed)
    Abstract [en]

     

    A simple setup for dynamic air sampling using a solid-phase microextraction (SPME) device

    designed for use in the field was evaluated for organophosphate triester vapour under both

    equilibrium and non-equilibrium conditions. The effects of varying the applied airflows in the

    sampling device were evaluated in order to optimise the system with respect to the Reynolds

    number and magnitude of the boundary layer that developed near the surface. Further, the

    storage stability of the analytes was studied for both capped and uncapped 100-

     

     

    m

    m PDMS fibres.

    Organophosphate triesters are utilized on large scales as flame-retardants and/or plasticizers, for

    instance in upholstered furniture. In indoor working environments these compounds have become

    common components in the surrounding air. Measurements were performed in a recently

    furnished working environment and the concentration of tris(2-choropropyl) phosphate was

    found to be 7

     

     

    mg m23

    .

  • 17.
    Isetun, Sindra
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Evaluation of solid-phase microextraction with PDMS for air sampling of gaseous organophosphate flame-retardants and plasticizers2004In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 380, no 2, p. 319-324Article in journal (Refereed)
    Abstract [en]

    As an inexpensive, simple, and low-solvent consuming extraction technique, the suitability of solid-phase microextraction (SPME) with polydimethylsiloxane (PDMS) sorbent was investigated as a quantitative method for sampling gaseous organophosphate triesters in air. These compounds have become ubiquitous in indoor air, because of their widespread use as additive flame retardants/plasticizers in various indoor materials. Results obtained by sampling these compounds at controlled air concentrations using SPME and active sampling on glass fibre filters were compared to evaluate the method. A constant linear airflow of 10 cm s–1 over the fibres was applied to increase the extraction rate. For extraction of triethyl phosphate with a 100-m PDMS fibre, equilibrium was achieved after 8 h. The limit of detection was determined to be less than 10 pg m–3. The PDMS–air partition coefficients, Kfs, for the individual organophosphate triesters were determined to be in the range 5–60×106 at room temperature (22–23°C). Air measurements were performed utilising the determined coefficients for quantification. In samples taken from a lecture room four different airborne organophosphate esters were identified, the most abundant of which was tris(chloropropyl) phosphate, at the comparatively high level of 1.1 g m–3. The results from SPME and active sampling had comparable repeatability (RSD less than 17%), and the determined concentrations were also similar. The results suggest that the investigated compounds were almost entirely associated with the gaseous phase at the time and place sampled.

  • 18.
    Jiang, Liying
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Johnston, Eric
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åberg, K. Magnus
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Strategy for quantifying trace levels of BMAA in cyanobacteria by LC/MS/MS2013In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 405, no 4, p. 1283-1292Article in journal (Refereed)
    Abstract [en]

    The cyanobacterial neurotoxin β-N-methylamino--alanine (BMAA) is an amino acid that is putatively associated with the pathology of amyotrophic lateral sclerosis/Parkinsonism –dementia complex (ALS-PDC) disease. It raises serious health risk concerns since cyanobacteria are ubiquitous thus making human exposure almost inevitable. The identification and quantification of BMAA in cyanobacteria is challenging because it is present only in trace amounts and occurs alongside structurally similar compounds such as BMAA isomers. This work describes an enhanced liquid chromatography/tandem mass spectrometry platform that can distinguish BMAA from its isomers β-amino-N-methyl-alanine, N-(2-oethyl) glycine (AEG), and 2,4-diaminobutyric acid, thus ensuring confident identification of BMAA. The method's sensitivity was improved fourfold by a post-column addition of acetonitrile. The instrument and method limits of detection were shown to be 4.2 fmol/injection (or 0.5 g/one column) and 0.1 μg/g dry weight of cyanobacteria, respectively. The quantification method uses synthesized deuterated BMAA as an internal standard and exhibits good linearity, accuracy, and precision. Matrix effects were also investigated, revealing an ion enhancement of around 18 %. A lab-cultured cyanobacterial sample (Leptolyngbya PCC73110) was analyzed and shown to contain about 0.73 μg/g dry weight BMAA. The isomer AEG, whose chromatographic properties closely resemble those of BMAA, was also detected. These results highlight the importance of distinguishing BMAA from its isomers for reliable identification as well as providing a sensitive and accurate quantification method for measuring trace levels of BMAA in cyanobacterial samples.

  • 19. Johansson, Staffan
    et al.
    Redeby, Theres
    Altamore, Timothy M.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Börje, Anna
    Mechanistic Proposal for the Formation of Specific Immunogenic Complexes via a Radical Pathway: A Key Step in Allergic Contact Dermatitis to Olefinic Hydroperoxides2009In: Chemical Research in Toxicology, ISSN 0893-228X, E-ISSN 1520-5010, Vol. 22, no 11, p. 1774-1781Article in journal (Refereed)
    Abstract [en]

    The widespread use of scented products causes an increase of allergic contact dermatitis to fragrance compounds in Western countries today. Many fragrance compounds are prone to autoxidation, forming hydroperoxides as their primary oxidation products. Hydroperoxides are known to be strong allergens and to form specific immunogenic complexes. However, the mechanisms for the formation of the immunogenic complexes are largely unknown. We have investigated this mechanism for (5R)-5-isopropenyl-2-methyl-2-cyclohexene-1-hydroperoxide (Lim-2-OOH) by studying the formation of adducts in the reaction between this hydroperoxide and 5,10,15,20-tetraphenyl-21H,23H-porphine iron(III) chloride (Fe(III)TPPCl) in the presence of protected cysteine (NAc-Cys-OMe) or glutathione (GSH). Isolated adducts originate from the addition of the thiol group of NAc-Cys-OMe over the carbon−carbon double bonds of carvone. Furthermore, adducts between NAc-Cys-OMe and carveol as well as between GSH and carvone have been identified. The formation of these adducts most likely proceeds via the radical thiol−ene mechanism. The addition of a terpene moiety to cysteine offers an explanation of the specificity of the immune response to structurally different hydroperoxides. These results also explain the lack of cross-reactivity between carvone and Lim-2-OOH. In conclusion, we propose that immunogenic complexes of olefinic hydroperoxides can be formed via the radical thiol−ene mechanism. These complexes will be specific for the individual olefinic hydroperoxides due to the inclusion of a terpene moiety derived from the hydroperoxide.

  • 20. Karlberg, Ann-Therese
    et al.
    Albadr, Mhd-Hussam
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Tracing colophonium in consumer products2021In: Contact Dermatitis, ISSN 0105-1873, E-ISSN 1600-0536, Vol. 85, no 6, p. 671-678Article in journal (Refereed)
    Abstract [en]

    Background: Colophonium (rosin) can cause allergic contact dermatitis, mainly due to autoxidation of abietic acid (AbA). Products containing >= 0.1% colophonium should be labeled with EUH208 - Contains rosin; colophony. May produce an allergic reaction. How should this be measured?

    Objective: To compare the results from different strategies for estimating colophonium levels in consumer products: (a) from AbA, and (b) the sum of all major resin acids. To investigate the ratio of 7-oxodehydroabietic acid (7-O-DeA)/AbA as indication of autoxidation.

    Methods: Resin acids were extracted from consumer products, derivatized, and then separated by gas chromatography/mass spectrometry (GC/MS).

    Results: Resin acids were detected in 9 of 15 products. No product contained colophonium >= 0.1%. Estimation based on AbA resulted in underestimation of the colophonium levels in four of nine products. For three products, the obtained levels from this strategy were only one of two compared to when estimating from the sum of all resin acids. The ratio 7-O-DeA/AbA varied from 74% to 1.4%.

    Conclusions: We propose to measure colophonium based on the sum of all detectable major resin acids, including 7-O-DeA. The ratio of 7-O-DeA/AbA should be used as a marker of autoxidation, indicating an increased risk of sensitization. The presented analytical method is simple to use and suitable for further screening studies.

  • 21.
    Karlsson, Isabella
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Samuelsson, Kristin
    Ponting, David J.
    Törnqvist, Margareta
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Peptide Reactivity of Isothiocyanates - Implications for Skin Allergy2016In: Scientific Reports, E-ISSN 2045-2322, Vol. 6, article id 21203Article in journal (Refereed)
    Abstract [en]

    Skin allergy is a chronic condition that affects about 20% of the population of the western world. This disease is caused by small reactive compounds, haptens, able to penetrate into the epidermis and modify endogenous proteins, thereby triggering an immunogenic reaction. Phenyl isothiocyanate (PITC) and ethyl isothiocyanate (EITC) have been suggested to be responsible for allergic skin reactions to chloroprene rubber, the main constituent of wetsuits, orthopedic braces, and many types of sports gear. In the present work we have studied the reactivity of the isothiocyanates PITC, EITC, and tetramethylrhodamine-6-isothiocyanate (6-TRITC) toward peptides under aqueous conditions at physiological pH to gain information about the types of immunogenic complexes these compounds may form in the skin. We found that all three compounds reacted quickly with cysteine moieties. For PITC and 6-TRITC the cysteine adducts decomposed over time, while stable adducts with lysine were formed. These experimental findings were verified by DFT calculations. Our results may suggest that the latter are responsible for allergic reactions to isothiocyanates. The initial adduct formation with cysteine residues may still be of great importance as it prevents hydrolysis and facilitates the transport of isothiocyanates into epidermis where they can form stable immunogenic complexes with lysine-containing proteins.

  • 22.
    Karlsson, Isabella
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Samuelsson, Kristin
    Simonsson, Carl
    Stenfeldt, Anna-Lena
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Jonsson, Charlotte
    Karlberg, Ann-Therese
    The Fate of a Hapten - From the Skin to Modification of Macrophage Migration Inhibitory Factor (MIF) in Lymph Nodes2018In: Scientific Reports, E-ISSN 2045-2322, Vol. 8, article id 2895Article in journal (Refereed)
    Abstract [en]

    Skin (contact) allergy, the most prevalent form of immunotoxicity in humans, is caused by low molecular weight chemicals (haptens) that penetrate stratum corneum and modify endogenous proteins. The fate of haptens after cutaneous absorption, especially what protein(s) they react with, is largely unknown. In this study the fluorescent hapten tetramethylrhodamine isothiocyanate (TRITC) was used to identify hapten-protein conjugates in the local lymph nodes after topical application, as they play a key role in activation of the adaptive immune system. TRITC interacted with dendritic cells but also with T and B cells in the lymph nodes as shown by flow cytometry. Identification of the most abundant TRITC-modified protein in lymph nodes by tandem mass spectrometry revealed TRITC-modification of the N-terminal proline of macrophage migration inhibitory factor (MIF) - an evolutionary well-conserved protein involved in cell-mediated immunity and inflammation. This is the first time a hapten-modified protein has been identified in lymph nodes after topical administration of the hapten. Most haptens are electrophiles and can therefore modify the N-terminal proline of MIF, which has an unusually reactive amino group under physiological conditions; thus, modification of MIF by haptens may have an immunomodulating role in contact allergy as well as in other immunotoxicity reactions.

  • 23.
    Keshavarzi, Neda
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mashayekhy Rad, Farshid
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Mace, Amber
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ansari, Farhan
    Akhtar, Farid
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Berglund, Lars
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nanocellulose-Zeolite Composite Films for Odor Elimination2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 26, p. 14254-14262Article in journal (Refereed)
    Abstract [en]

    Free standing and strong odor-removing composite films of cellulose nanofibrils (CNF) with a high content of nanoporous zeolite adsorbents have been colloidally processed. Thermogravimetric desorption analysis (TGA) and infrared spectroscopy combined with computational simulations showed that commercially available silicalite-1 and ZSM-5 have a high affinity and uptake of volatile odors like ethanethiol and propanethiol, also in the presence of water. The simulations showed that propanethiol has a higher affinity, up to 16%, to the two zeolites compared with ethanethiol. Highly flexible and strong free-standing zeolite CNF films with an adsorbent loading of 89 w/w% have been produced by Ca-induced gelation and vacuum filtration. The CNF-network controls the strength of the composite films and 100 mu m thick zeolite CNF films with a CNF content of less than 10 vol % displayed a tensile strength approaching 10 MPa. Headspace solid phase microextraction (SPME) coupled to gas chromatography mass spectroscopy (GC/MS) analysis showed that the CNF zeolite films can eliminate the volatile thiol-based odors to concentrations below the detection ability of the human olfactory system. Odor removing zeolite-cellulose nanofibril films could enable improved transport and storage of fruits and vegetables rich in odors, for example, onion and the tasty but foul-smelling South-East Asian Durian fruit.

  • 24.
    Leck, Caroline
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gao, Qiuju
    Stockholm University, Faculty of Science, Department of Meteorology .
    Mashayekhy Rad, Farshid
    Stockholm University, Faculty of Science, Department of Meteorology . Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Size-resolved atmospheric particulate polysaccharides in the high summer Arctic2013In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 13, no 24, p. 12573-12588Article in journal (Refereed)
    Abstract [en]

    Size-resolved aerosol samples for subsequent quantitative determination of polymer sugars (polysaccharides) after hydrolysis to their subunit monomers (monosaccharides) were collected in surface air over the central Arctic Ocean during the biologically most active summer period. The analysis was carried out by novel use of liquid chromatography coupled with highly selective and sensitive tandem mass spectrometry. Polysaccharides were detected in particle sizes ranging from 0.035 to 10 mu m in diameter with distinct features of heteropolysaccharides, enriched in xylose, glucose + mannose as well as a substantial fraction of deoxysugars. Polysaccharides, containing deoxysugar monomers, showed a bimodal size structure with about 70% of their mass found in the Aitken mode over the pack ice area. Pentose (xylose) and hexose (glucose + mannose) had a weaker bimodal character and were largely found with super-micrometer sizes and in addition with a minor sub-micrometer fraction. The concentration of total hydrolysable neutral sugars (THNS) in the samples collected varied over two orders of magnitude (1 to 160 pmol m(-3)) in the supermicrometer size fraction and to a somewhat lesser extent in sub-micrometer particles (4 to 140 pmol m(-3)). Lowest THNS concentrations were observed in air masses that had spent more than five days over the pack ice. Within the pack ice area, about 53% of the mass of hydrolyzed polysaccharides was detected in sub-micrometer particles. The relative abundance of sub-micrometer hydrolyzed polysaccharides could be related to the length of time that the air mass spent over pack ice, with the highest fraction (> 90 %) observed for > 7 days of advection. The aerosol samples collected onboard ship showed similar monosaccharide composition, compared to particles generated experimentally in situ at the expedition's open lead site. This supports the existence of a primary particle source of polysaccharide containing polymer gels from open leads by bubble bursting at the air-sea interface. We speculate that the occurrence of atmospheric surface-active polymer gels with their hydrophilic and hydrophobic segments, promoting cloud droplet activation, could play a potential role as cloud condensation nuclei in the pristine high Arctic.

  • 25.
    Leck, Caroline
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Qiuju, Gao
    Stockholm University, Faculty of Science, Department of Meteorology .
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Size-resolved polysaccharides in summer high Arctic aerosol relevant to cloud formation.Manuscript (preprint) (Other academic)
  • 26.
    Lim, Hwanmi
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Silvergren, Sanna
    Spinicci, Silvia
    Rad, Farshid Mashayekhy
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johansson, Christer
    Stockholm University, Faculty of Science, Department of Environmental Science. SLB, Sweden.
    Contribution of wood burning to exposures of PAHs and oxy-PAHs in Eastern Sweden2022In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 22, no 17, p. 11359-11379Article in journal (Refereed)
    Abstract [en]

    A growing trend in developed countries is the use of wood as fuel for domestic heating due to measures taken to reduce the usage of fossil fuels. However, this imposed another issue with the environment and human health. That is, the emission from wood burning contributed to the increased level of atmospheric particulates and the wood smoke caused various respiratory diseases. The aim of this study was to investigate the impact of wood burning on the polycyclic aromatic hydrocarbons (PAHs) in air PM10 using known wood burning tracers, i.e. levoglucosan, mannosan and galactosan from the measurement at the urban background and residential areas in Sweden. A yearly measurement from three residential areas in Sweden showed a clear seasonal variation of PAHs during the cold season mainly from increased domestic heating and meteorology. Together, an increased sugar level assured the wood burning during the same period. The sugar ratio (levoglucosan(mannosan+galactosan)) was a good marker for wood burning source such as the wood type used for domestic heating and garden waste burning. On the Walpurgis Night, the urban background measurement demonstrated a dramatic increase in levoglucosan, benzo[a]pyrene (B[a]P) and oxygenated PAHs (OPAHs) concentrations from the increased wood burning. A significant correlation between levoglucosan and OPAHs was observed suggesting OPAHs to be an indicator of wood burning together with levoglucosan. The levoglucosan tracer method and modelling used in predicting the B[a]P concentration could not fully explain the measured levels in the cold season. The model showed that the local wood source contributed to 98 % of B[a]P emissions in the Stockholm area and 2 % from the local traffic. However, non-local sources were dominating in the urban background (60 %). A further risk assessment estimated that the airborne particulate PAHs caused 13.4 cancer cases per 0.1 million inhabitants in Stockholm County.

  • 27.
    Maddalo, Gianluca
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Shariatgorji, Mohammadreza
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Adams, Christopher M.
    Fung, Eva
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Zubarev, Roman A.
    Sedzik, Jan
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Porcine P2 myelin protein primary structure and bound fatty acids determined by mass spectrometry2010In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 397, no 5, p. 1903-1910Article in journal (Refereed)
    Abstract [en]

    Complementary collision-induced/electron capture dissociation Fourier-transform ion cyclotron resonance mass spectrometry was used to fully sequence the protein P2 myelin basic protein. It is an antigenic fatty-acid-binding protein that can induce experimental autoimmune neuritis: an animal model of Guillain-Barre syndrome, a disorder similar in etiology to multiple sclerosis. Neither the primary structure of the porcine variant, nor the fatty acids bound by the protein have been well established to date. A 1.8-angstrom crystal structure shows but a bound ligand could not be unequivocally identified. A protocol for ligand extraction from protein crystals has been developed with subsequent gas chromatography MS analysis allowing determination that oleic, stearic, and palmitic fatty acids are associated with the protein. The results provide unique and general evidence of the utility of mass spectrometry for characterizing proteins from natural sources and generating biochemical information that may facilitate attempts to elucidate the causes for disorders such as demyelination.

  • 28.
    Mashayekhy Rad, Farshid
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Leck, Caroline
    Stockholm University, Faculty of Science, Department of Meteorology .
    Ilag, Leopold L.
    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.
    Investigation of ultrahigh-performance liquid chromatography/travelling-wave ion mobility/time-of-flight mass spectrometry for fast profiling of fatty acids in the high Arctic sea surface microlayer2018In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 32, no 12, p. 942-950Article in journal (Refereed)
    Abstract [en]

    Rationale

    Fatty acids are enriched in the ocean surface microlayer (SML) and have as a consequence been detected worldwide in sea spray aerosols. In searching for a relationship between the properties of the atmospheric aerosol and its ability to form cloud condensation nuclei and to promote cloud droplet formation over remote marine areas, the role of surface active fatty acids sourced from the SML is of interest to be investigated. Here is presented a fast method for profiling of major fatty acids in SML samples collected in the high Arctic (89 °N, 1 °W) in the summer of 2001.

    Methods

    UHPLC/travelling‐wave ion mobility spectrometry (TWIMS)/time‐of‐flight (TOF) mass spectrometry (MS) for profiling was evaluated and compared with UHPLC/TOFMS. No sample preparation, except evaporation and centrifugation, was necessary to perform prior to the analysis.

    Results

    TOFMS data on accurate mass, isotopic ratios and fragmentation patterns enabled identification of the fatty acids. The TWIMS dimension added to the selectivity by extensive reduction of the noise level and the entire UHPLC/TWIMS/TOFMS method provided a fast profiling of the acids, ranging from C8 to C24. Hexadecanoic and octadecanoic acids were shown to yield the highest signals among the fatty acids detected in a high Arctic SML sample, followed by the unsaturated octadecenoic and octadecadienoic acids. The predominance of signal from even‐numbered carbon chains indicates a mainly biogenic origin of the detected fatty acids.

    Conclusions

    This study presents a fast alternative method for screening and profiling of fatty acids, which has the advantage of not requiring any complicated sample preparation thus limiting the loss of analytes. Almost no manual handling, together with the very small sample volumes needed, is certainly beneficial for the determination of trace amounts and should open up the field of applications to also include atmospheric aerosol and fog.

  • 29.
    Mashayekhy Rad, Farshid
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Spinicci, Silvia
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Silvergren, Sanna
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Validation of a HILIC/ESI-MS/MS method for the wood burning marker levoglucosan and its isomers in airborne particulate matter2018In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 211, p. 617-623Article in journal (Refereed)
    Abstract [en]

    In the present study, a methodology involving hydrophilic interaction liquid chromatography (HILIC) and electrospray (ESI) tandem mass spectrometry (MS/MS) was developed for measurement of anhydrous monosaccharides as markers for wood burning in atmospheric aerosols, PM10. No extensive sample preparation, other than ultrasound-assisted solvent extraction and evaporation, was applied. A pentahydroxysilica column enabled separation of levoglucosan from mannosan and galactosan within 5 min and the quantitative performance was validated using the standard reference materials (SRM) 1649a and 1649b. The experimentally obtained results for SRMs were in agreement with values previously reported in other studies. Achieved instrumental limits of detection (LODs) were below 10 pg injected on column, corresponding to LODs in air lower than 0.10 ng/m3 for all measured isomers for 2–3 day sampling with 1.0 m−3 h−1 sampling rate.

    The validated method was used for the determination of levoglucosan and its isomers in atmospheric aerosols collected in three different Swedish urban areas during the winter and summer time in 2017. The total measured concentrations for levoglucosan and galactosan + mannosan were determined to be between 78 and 167 ng/m3 in January 2017, which is approximately 10-times higher compared to the levels detected in July, reflecting the higher frequency of wood burning for heating during the cold season. Calculated concentration ratios between levoglucosan and its isomers in the urban area samples indicated mostly mixed softwood/hardwood combustion in winter time; on the other hand, softwood burning was observed as the major emission in summer time.

  • 30.
    Mashayekhy Rad, Farshid
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Stockholm University, Faculty of Science, Department of Meteorology .
    Zurita, Javier
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Gilles, Philippe
    Rutgeerts, Laurens A. J.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Leck, Caroline
    Stockholm University, Faculty of Science, Department of Meteorology .
    Measurements of Atmospheric Proteinaceous Aerosol in the Arctic Using a Selective UHPLC/ESI-MS/MS Strategy2019In: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 30, no 1, p. 161-173Article in journal (Refereed)
    Abstract [en]

    In this article, an analytical methodology to investigate the proteinaceous content in atmospheric size-resolved aerosols collected at the Zeppelin observatory (79 °N, 12 °E) at Ny Ålesund, Svalbard, from September to December 2015, is proposed. Quantitative determination was performed after acidic hydrolysis using ultrahigh-performance liquid chromatography in reversed-phase mode coupled to electrospray ionization tandem mass spectrometry. Chromatographic separation, as well as specificity in the identification, was achieved by derivatization of the amino acids with N-butyl nicotinic acid N-hydroxysuccinimide ester prior to the analysis. The chromatographic run was performed within 11 min and instrumental levels of detection (LODs) were between 0.2 and 8.1 pg injected on the column, except for arginine which exhibited an LOD of 37 pg. Corresponding method LODs were between 0.01 and 1.9 fmol/m3, based on the average air sampling volume of 57 m3. The sum of free amino acids and hydrolyzed polyamino acids was shown to vary within 6–2914 and 0.02–1417 pmol/m3 for particles in sizes < 2 and 2–10 μm in equivalent aerodynamic diameter, respectively. Leucine, alanine, and valine were the most abundant among the amino acids in both aerosol size fractions. In an attempt to elucidate source areas of the collected aerosols, 5- to 10-day 3D backward trajectories reaching the sampling station were calculated. Overall, the method described here provides a first time estimate of the proteinaceous content, that is, the sum of free and polyamino acids, in size-resolved aerosols collected in the Arctic.

  • 31. Möller, Kristina
    et al.
    Davies, Ronnie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Fred, Charlotta
    Törnqvist, Margareta
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Evaluation of molecularly imprinted solid-phase extraction for a 1,2:3,4-diepoxybutane adduct to valine in haemoglobin2010In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 878, no 27, p. 2497-2501Article in journal (Refereed)
    Abstract [en]

    A molecularly imprinted polymer, MIP, was prepared and evaluated as SPE sorbent for a cyclicized adduct formed to N-terminal valine (Pyr-Val) in hemoglobin from 1,2:3,4-diepoxybutane (DEB). This metabolite plays an important role in the carcinogenesis of 1,3-butadiene. The hydrazide of Pyr-Val, formed after hydrazinolysis of hemoglobin, as well as necessary standards was synthesized. The MIP was prepared from methacrylic acid with a structure analogue to the investigated adduct as template and the method was developed for aqueous conditions. Selective desorption was achieved when the sample was washed with water after loading in 10% acetonitrile. The primary interaction with the binding sites in the imprints was most likely of ionic character. Quantification of the Pyr-Val adduct was performed with LC/ESI-MS/MS, yielding an instrumental LOD of 150 pg injected amount.

  • 32. Natsch, Andreas
    et al.
    Gunthardt, Barbara F.
    Corbi, Elise
    Peres, Christophe
    Dusterloh, Andre
    Leijs, Hans
    van Strien, Michel
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Calandra, Michael J.
    Wang, Ying
    Interlaboratory evaluation of methods to quantify skin sensitizing hydroperoxides potentially formed from linalool and limonene in perfumes2017In: Flavour and fragrance journal, ISSN 0882-5734, E-ISSN 1099-1026, Vol. 32, no 4, p. 277-285Article in journal (Refereed)
    Abstract [en]

    The fragrant terpenes limonene and linalool can form skin sensitizing hydroperoxides upon prolonged exposure to air. Recently, high frequencies of positive patch tests to oxidized linalool and limonene were reported from multiple dermatological centres. However, there is a lack of data indicating potential sources of consumer exposure to sensitizing doses of terpene hydroperoxides which explains this frequent contact allergy. Within the IDEA project ( International Dialogue for the Evaluation of Allergens; http://ideaproject.info/), a taskforce was formed to drive analytical method development and evaluation. In an inter-laboratory study in five laboratories, a method based on hydroperoxide reduction combined with GC-MS was tested for reproducibility. Blinded samples of commercial fine fragrances were spiked with four different hydroperoxides. In samples spiked with 100-200 mu g/ml, an average recovery of 86-105% with a relative standard deviation between laboratories of 7.4-22% was found. In samples spiked with 2050 mu g/ml, the recovery was 85-91%. The reduction approach offers a transferable and reproducible method to indirectly detect low levels of hydroperoxides, at least in fine fragrances. Ideally, one would prefer to directly detect the parent hydroperoxide. Therefore the same samples were further tested with three LC-based methods directly detecting the parent hydroperoxide. LC coupled to chemiluminescence, LC-Q-TOF-MS or LC-orbitrap-MS were used. Results indicate that with specific gradients a separation of the four analytes and quantification in the fragrance matrix can be achieved. Results of this method evaluation study present a toolbox of methods to detect terpene hydroperoxides to further investigate consumer exposure.

  • 33.
    Nilsson, Ulrika
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Karlberg, Ann-Therese
    Lassen, Pia
    Development and validation of a method for the analysis of colophonium in cosmetic products: Rapport till Dansk Miljöstyrelse, Dec 07. Dansk Miljöundersögelser2007Report (Other academic)
  • 34.
    Nilsson, Ulrika Nilsson
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Berglund, Naghmeh
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Lindahl, F
    Axelsson, Sara
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Redeby, Theres
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    SPE and HPLC/UV of resin acids in colophonium-containing products2008In: Journal of Separation Science, Vol. 31, no 15, p. 2784-2790Article in journal (Refereed)
    Abstract [en]

    A new method, involving SPE and HPLC/UV diode-array detection (DAD), was developed for the quantification of colophonium components in different consumer products, such as cosmetics. Colophonium is a common cause of contact dermatitis since its components can oxidize into allergens on exposure to air. Three different resin acids were used as markers for native and oxidized colophonium, abietic acid (AbA), dehydroabietic acid (DeA), and 7-oxodehydroabietic acid (7-O-DeA). The SPE method, utilizing a mixed-mode hydrophobic and anion exchange retention mechanism, was shown to yield very clean extracts. The use of a urea-embedded C12 HPLC stationary phase improved the separation of the resin acids compared to common C18. Concentrations higher than 2 mg/g of both AbA and DeA were detected in wax strips. In this product also 7-O-DeA, a marker for oxidized colophonium, was detected at a level of 28 μg/g. The LODs were in the range of 7–19 μg/g and the LOQs 22–56 μg/g. The method is simple to use and can be applied on many types of technical products, not only cosmetics. For the first time, a method for technical products was developed, which separates AbA from pimaric acid

  • 35.
    Nordqvist, Yvonne
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Melin, Jens
    Nilsson, Ulrika
    Johansson, Rolf
    Colmsjö, Anders
    Comparison of denuder and impinger sampling for determination of gaseous toluene diisocyanate (TDI)2001In: Fresenius´ Journal of Analytical Chemistry, ISSN 0937-0633, Vol. 371, no 1, p. 39-43Article in journal (Refereed)
    Abstract [en]

     

    An air-sampling method employing denuders coated inside with a chemisorptive stationary phase has been evaluated for analysis of the hazardous gaseous 2,4 and 2,6 isomers of toluene diisocyanate (TDI). The denuder stationary phase consisted of polydimethylsiloxane (SE-30) to which dibutylamine (DBA) was added as a reagent for derivatization of TDI. The accuracy and precision of sampling by means of denuders were shown to differ only slightly from those of the established impinger method. The denuder method was, however, also shown to be suitable for long-term measurements (up to 8 h). The limit of determination (LOD) of the method, including LC-APCI-MS-MS analysis, was found to be 1.9 µg m-3 and 1.2 µg m-3 for 2,4- and 2,6-TDI, respectively, for short-term measurements (15 min). Significant lower LOD was obtained for long-term measurements.This is well below the Occupational Safety and Health Administration (OSHA) 8-h TWA (time weighted average) exposure limit, which is 40 µg m-3 for the sum of the TDI isomers. The denuder method was also found to be robust and easy to handle. The samplers can be prepared several days before sampling with no loss in performance. The contents of denuders should, on the other hand, be extracted immediately after sampling to prevent degradation of the isocyanate derivatives formed.

     

  • 36.
    Nordqvist, Yvonne
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Colmsjö, Anders
    Evaluation of denuder sampling for a mixture of three common gaseous diisocyanates2003In: Analytical and bioanalytical chemistry, ISSN 1618-2642, Vol. 375, no 6, p. 786-791Article in journal (Refereed)
    Abstract [en]

    A denuder sampler has been evaluated for a mixture of three gaseous diisocyanates, i.e. toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI). Sampling was performed at a total concentration of diisocyanates close to the Swedish occupational exposure limit (OEL), which is 10 ppbv (69–92 µg m–3), for a 5-min period. The denuder tube was coated with a chemosorptive stationary phase consisting of SE-30 (polydimethylsiloxane) and the derivatising reagent dibutylamine (DBA). It was shown that the denuder has a collection efficiency for HDI and IPDI comparable to that of an impinger method, while sampling of TDI resulted in an 8% lower concentration. Both short-term (15 min) and long-term (8 h) sampling periods were shown to yield reproducible results. For 8-h measurements, a sampling flow rate of 5 mL min–1 was shown to be suitable for the investigated concentration range, i.e. 10–100 ppbv (69–921 µg m–3). A flow rate of 25 mL min–1 or higher resulted in breakthrough after 8 h due to chromatography of the compounds in the adsorbent. The limit of detection (LOD) for the air sampling method is nearly 500 times lower than the OEL. The denuder tubes can be prepared at least 10 days prior to sampling without degradation of performance. Furthermore, they can be stored up to 6 days in a freezer after sampling without significant loss of analytes.

  • 37.
    Nordqvist, Yvonne
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry. Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry. Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry. Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Investigation of a cylindrical chemosorptive denuder for sampling and phase separation of toluene diisocyanate aerosols.2005In: Anal Bioanal Chem, ISSN 1618-2642, Vol. 382, no 5, p. 1294-9Article in journal (Other academic)
  • 38.
    Nordqvist, Yvonne
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Colmsjö, Anders
    Investigation of a cylindrical chemosorptive denuder for sampling and phase separation of toluene diisocyanate aerosols2005In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 382, no 5, p. 1294-1299Article in journal (Refereed)
    Abstract [en]

    A cylindrical chemosorptive denuder in series with a glass fibre filter has been evaluated for sampling toluene diisocyanate (TDI) aerosols. The sampler is designed for measuring personal exposure to diisocyanates. Several denuder coatings and derivatising reagents were investigated. Dimethylpolysiloxane (SE-30) and 5% phenyl dimethylpolysiloxane (SE-54) with either dibutylamine (DBA) or dipentylamine (DPeA) as derivatising reagents yielded the lowest vapour breakthrough (the amount (%) of the vapour that passes through the denuder), close to values predicted by theory. Immobilisation of the SE-30 denuder coating by in-situ cross-linking yielded comparable results. With an SE-30/DBA-coated denuder operating within an airflow range of 100–500 mL min<sup>−1</sup>, the phase separation was shown to be consistent with theoretical predictions derived by use of the Gormley–Kennedy equation. This provides a means of calculating the vapour breakthrough and correcting experimentally obtained values with regard to vapour–particulate phase distribution, suggesting that the denuder can provide accurate phase-distribution measurements. The SE-30/DBA denuder can be used over a concentration range spanning nearly six orders of magnitude. Its capacity is sufficient to perform 15-min exposure measurements of a TDI aerosol with air concentrations as high as 1,700 μg m<sup>−3</sup>, 40 times higher than the Swedish occupational exposure limit (OEL). At the other end of the range, the estimated limit of detection (LOD) was less than 2 ng m<sup>−3</sup> for both the vapour and the aerosol phases when LC–ESI–MS–MS was used for chemical analysis.

  • 39.
    Nordqvist, Yvonne
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Dahl, Andreas
    Gudmundsson, Anders
    Evaluation of a cylindrical denuder designed for personal exposure measurements of methylene diphenyl diisocyanate aerosolsManuscript (preprint) (Other (popular science, discussion, etc.))
  • 40.
    Olsson, Petter
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Holmbäck, Jan
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Herslöf, Bengt
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Separation And Identification Of Lipid Classes By Normal Phase Lc-Esi/Ms/Ms On A Cyanopropyl Column2014In: European Journal of Lipid Science and Technology, ISSN 1438-7697, E-ISSN 1438-9312, Vol. 116, no 5, p. 653-658Article in journal (Refereed)
    Abstract [en]

    In order to establish a versatile and convenient method for the analysis of lipids, electrospray ionization tandem mass spectrometry (ESI-MS/MS) was applied to a HPLC separation on a cyanopropyl-bonded stationary phase. A binary gradient mobile phase system consisting of hexane, toluene, methanol and a stable electrospray yielding sodium adduct ions could be used to generate specific product ions in MS/MS mode. By applying the LC/ESI-MS/MS method on an egg yolk sample, 29 different molecular species of phosphatidylethanolamines, phosphatidylcholines, and lysophosphatidylcholines could be detected within 25 min.

  • 41. Raison-Peyron, Nadia
    et al.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Du-Thanh, Aurélie
    Karlberg, Ann-Therese
    Contact Dermatitis From Unexpected Exposure to Rosin From a Toilet Seat2013In: Dermatitis, ISSN 1710-3568, E-ISSN 2162-5220, Vol. 24, no 3, p. 149-150Article in journal (Other academic)
  • 42.
    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.

  • 43.
    Ramzy, Ahmad G.
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Hagvall, Lina
    Pei, Mansoureh N.
    Samuelsson, Kristin
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Investigation of diethylthiourea and ethyl isothiocyanate as potent skin allergens in chloroprene rubber2015In: Contact Dermatitis, ISSN 0105-1873, E-ISSN 1600-0536, Vol. 72, no 3, p. 139-146Article in journal (Refereed)
    Abstract [en]

    Background

    Exposure to chloroprene rubber has resulted in numerous cases of allergic contact dermatitis, attributed to organic thiourea compounds used as vulcanization accelerators. However, thiourea compounds are not considered to be strong haptens.

    Objectives

    To analyse common commercial chloroprene materials for their contents of diethylthiourea (DETU), dibutylthiourea (DBTU), diphenylthiourea (DPTU), and their degradation products, isothiocyanates; and to investigate the sensitization potencies of possible degradation products of the mentioned thiourea compounds.

    Methods

    Liquid chromatography/mass spectrometry (MS) was used for quantification of organic thiourea compounds in chloroprene products, such as medical, sports and diving gear; isothiocyanates were measured by solid-phase microextraction/gas chromatography/MS. Sensitization potencies were determined with the murine local lymph node assay (LLNA).

    Results

    DETU was identified at concentrations of 2.7-9.4 mu g/cm(2) in all samples, whereas neither DBTU nor DPTU was detected. At 37 degrees C, degradation of DETU in the materials to ethyl isothiocyanate (EITC) was detected. EITC and ethyl isocyanate showed extreme and strong sensitization potencies, respectively, in the LLNA.

    Conclusions

    DETU can act as a prehapten, being degraded to EITC when subjected to body temperature upon skin contact. EITC could thus be the culprit behind allergic contact dermatitis caused by chloroprene rubber.

  • 44.
    Ramzy, Ahmad G.
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Lammintausta, K.
    Matura, M.
    Bråred Christensson, J.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Hagvall, L.
    Isothiocyanates are important as haptens in contact allergy to chloroprene rubber2017In: British Journal of Dermatology, ISSN 0007-0963, E-ISSN 1365-2133, Vol. 177, no 2, p. 522-530Article in journal (Refereed)
    Abstract [en]

    Background Contact allergy to chloroprene rubber products is well known. Thiourea compounds are considered the cause of allergy. Diethylthiourea commonly occurs in this type of product and can decompose to the sensitizer ethyl isothiocyanate. Objectives To investigate the clinical importance of degradation products and metabolites from organic thioureas in contact allergy to chloroprene rubber with a focus on isothiocyanates and isocyanates. Methods Patients with contact allergy to diphenylthiourea were patch tested with phenyl isothiocyanate and phenyl isocyanate. Patients with known contact allergy to diethylthiourea were retested with diethylthiourea, while chemical analyses of their chloroprene rubber products were performed. The stability of diethylthiourea, diphenylthiourea and dibutylthiourea in patch-test preparations was investigated. Liquid chromatography/mass spectrometry and solid-phase microextraction/gas chromatography were used for determination of organic thioureas and isothiocyanates. Results All patients allergic to diphenylthiourea reacted to phenyl isothiocyanate, two of eight reacted to phenyl isocyanate and six of eight reacted to diphenylthiourea. Four patients allergic to diethylthiourea reacted at retest; diethylthiourea was detected in all chloroprene rubber samples, with levels of 2-1200 nmol cm(-2). At 35 degrees C, ethyl isothiocyanate was emitted from all samples. Patch-test preparations of diethylthiourea, diphenylthiourea and dibutylthiourea all emitted the corresponding isothiocyanate, with diethylthiourea showing the highest rate of isothiocyanate emission. Conclusions Thiourea compounds are degraded to isothiocyanates, which are generally strong or extreme sensitizers, thus acting as prehaptens. This process occurs in both chloroprene rubber products and patch-test preparations. Positive reactions to phenyl isocyanate indicate cutaneous metabolism, as the only known source of exposure to phenyl isocyanate is through bioactivation of diphenylthiourea.

  • 45.
    Ramzy, 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 reversed and normal phase high-performance liquid chromatography/tandem mass spectrometry system for determination of linalool and limonene hydroperoxidesManuscript (preprint) (Other academic)
  • 46.
    Redeby, Theres
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.