Diisononyl cyclohexane-1,2-dicarboxylate (DINCH) – Determination of DINCH metabolites in urine by LC-MS/MS

Biomonitoring-Method – Translation of the German version from 2023

Holger Martin Koch¹ (Author of the method)
André Schütze¹ (Author of the method)
Wolfgang Völkel² (External verification)
Mandy Wöckner² (External verification)

¹ Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr University Bochum (IPA), Bürkle de la Camp Platz 1, 44789 Bochum, Germany
² Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit, Pfarrstraße 3, 80538 München, Germany

Abstract

The working group “Analyses in Biological Materials” of the German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area developed and verified the presented biomonitoring method. The method described herein allows for the determination of cyclohexane-1,2-dicarboxylic acid monocarboxyisooctyl ester (cx-MINCH), cyclohexane-1,2-dicarboxylic acid monohydroxyisononyl ester (OH-MINCH), cyclohexane-1,2-dicarboxylic acid monooxoisononyl ester (oxo-MINCH), and cyclohexane-1,2-dicarboxylic acid monoisononyl ester (MINCH) as specific metabolites of diisononyl cyclohexane-1,2-dicarboxylate (DINCH) in urine. For the determination, urine samples buffered to pH 6.0 are mixed with deuterated internal standards (ISTDs), enzymatically hydrolysed, and then subjected to online preconcentration. By way of automatic column-switching, the analytes are then transferred onto the analytical column in back-flush mode, where they are chromatographically separated and, following negative ionisation, quantified by tandem mass spectrometry. Calibration is carried out using calibration standards prepared in pooled urine and processed in the same way as the samples to be analysed.

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