title: High-throughput method for the analysis of ethylenethiourea with direct injection of hydrolysed urine using online on-column extraction liquid chromatography and triple quadrupole mass spectrometry.
abstract: Ethylenethiourea (ETU) is of major toxicological concern, since in experimental animal studies, ETU has shown a large spectrum of adverse effects. High occupational exposure can be found among agricultural workers or during manufacturing of ethylenbisdithiocarbamates (EBDC). For the general public, sources of environmental exposure may be residues of ETU in commercial products, food and beverages. For the determination of ETU in human urine we present a high-throughput online on-column extraction liquid chromatography triple quadrupole mass spectrometry method using direct injection of hydrolysed urine samples. This method is simple, user- and environmentally friendly and all sample preparation is performed in 96-well plates. A labelled ETU internal standard was used for quantification. The method showed a good sensitivity with a limit of quantification (LOQ) of 0.5ng ETU/mL urine and the calibration curve was linear in the range 0.25-200ng ETU/mL urine. The within-run, between-run and between-batch precision was between 6% and 13%. Alkaline hydrolysis considerably increased the levels of ETU indicating a potential conjugate. The method was applied in an experimental dermal exposure study in humans, with sample concentrations ranging from 0.4 to 5.0ng ETU/mL urine. The excretion in urine was 10% of the applied dose. The elimination profile seemed to differ between the two individuals. The results show an estimated half-life of ETU between 34 and 72h. Although the experiment is limited to two individuals, the data provide valuable and new information regarding the toxicokinetics of ETU after dermal exposure.
authors.affiliation: Division of Occupational and Environmental Medicine, Department of Laboratory Medicine, Faculty of Medicine, Lund University, SE-221 85 Lund, Sweden. eva.ekman@med.lu.se
authors.forename: Eva
authors.initials: E
authors.lastname: Ekman
authors.forename: Margaretha
authors.initials: M
authors.lastname: Maxe
authors.forename: Margareta
authors.initials: M
authors.lastname: Littorin
authors.forename: Bo A G
authors.initials: BA
authors.lastname: Jönsson
authors.forename: Christian H
authors.initials: CH
authors.lastname: Lindh
mesh_terms: D000328:Adult; D000368:Aged; D001331:Automation; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D004781:Environmental Exposure; D005031:Ethylenethiourea / Q000032:analysis*; D005260:Female; D005659:Fungicides, Industrial / Q000652:urine*; D057166:High-Throughput Screening Assays / Q000379:methods*; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D052616:Solid Phase Extraction; D014556:Urine / Q000737:chemistry*
chemical_list: D005659:Fungicides, Industrial; D005031:Ethylenethiourea
keywords: ADI; Biomarkers; CID; Dermal; EBDC; ETU; Ethylenethiourea; High-throughput; IS; LC/MS/MS; LOD; LOQ; QC; Urine; acceptable daily intake; b.w.; body weight; collision induced dissociation; ethylenbisdithiocarbamates; ethylenethiourea; internal standard; limit of detection; limit of quantification; liquid chromatography triple quadrupole mass spectrometry; quality control