Tri-(2-ethylhexyl) trimellitate – Determination of 1-MEHTM, 2-MEHTM, 5OH-1-MEHTM, 5OH-2-MEHTM, 5cx-1-MEPTM, and 5cx-2-MEPTM in urine by LC-MS/MS
Biomonitoring Method – Translation of the German version from 2025
Laura Kuhlmann1 (Method development)Elisabeth Eckert1 (Method development)
Christine Höllerer-Mittelmaier1 (Method development)
Thomas Göen1 (Method development; Head of the working group “Analyses in Biological Materials” of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft)
Veronika Spindler2 (External verification)
Gerhard Scherer2 (External verification)
Craig Sams3 (External verification)
Kate Jones3 (External verification)
Andrea Hartwig4 (Chair of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft)
MAK Commission5
1 Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute and Outpatient Clinic of Occupational, Social, and Environmental Medicine, Henkestraße 9–11, 91054 Erlangen, Germany
2 ABF Analytisch-biologisches Forschungslabor GmbH, Semmelweisstraße 5, 82152 Planegg, Germany
3 Health and Safety Executive (HSE) Science and Research Centre, Harpur Hill, SK17 9JN Buxton (Derbyshire), United Kingdom
4 Institute of Applied Biosciences, Department of Food Chemistry and Toxicology, Karlsruhe Institute of Technology (KIT), Adenauerring 20a, Building 50.41, 76131 Karlsruhe, Germany
5 Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft, Kennedyallee 40, 53175 Bonn, Germany
Abstract
The working group “Analyses in Biological Materials” of the German Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) developed and verified this biomonitoring method for the measurement of six specific metabolites of the plasticiser tri‑(2‑ethylhexyl) trimellitate (TEHTM) in urine. Specifically, this method determines two monoester isomers as primary hydrolysis products of TEHTM, 1‑mono-(2‑ethylhexyl) trimellitate (1‑MEHTM) and 2‑mono-(2‑ethylhexyl) trimellitate (2‑MEHTM), as well as the oxidatively formed secondary derivatives, namely 1‑mono-(2‑ethyl-5‑hydroxyhexyl) trimellitate (5OH‑1‑MEHTM), 2‑mono-(2‑ethyl-5‑hydroxyhexyl) trimellitate (5OH‑2‑MEHTM), 1‑mono-(2‑ethyl-5‑carboxypentyl) trimellitate (5cx‑1‑MEPTM), and 2‑mono-(2‑ethyl-5‑carboxypentyl) trimellitate (5cx‑2‑MEPTM). Determination is carried out after enzymatic hydrolysis of the urine sample as well as enrichment of the analytes by online SPE. Via integrated, automatic column-switching, the analytes are transferred onto the analytical column in backflush mode, separated by liquid chromatography, and quantified by tandem mass spectrometry. Calibration is performed using calibration standards prepared in pooled urine and processed analogously to the samples to be analysed. The following isotope-labelled substances are added to the urine samples as internal standards: D5‑1‑MEHTM, D5‑2‑MEHTM, D5‑5OH‑1‑MEHTM, D5‑5cx‑1‑MEPTM, and D5‑5cx‑2‑MEPTM. The method provides reliable and accurate analytical results, as shown by the good precision data with standard deviations no greater than 8%. Good accuracy data were obtained with mean relative recoveries in the range of 97–109%. The method is both selective and sensitive, and provides quantitation limits in the range of 0.04–0.12 μg/l.
