De-novo identification of specific exposure biomarkers of the alternative plasticizer di(2-ethylhexyl) terephthalate (DEHTP) after low oral dosage to male volunteers by HPLC-Q-Orbitrap-MS

Abstract

Context: Human exposure biomonitoring relies on the availability of specific, sensitive biomarkers. For emerging chemicals, the identification (prediction, synthesis, verification) of such biomarkers is time and cost intensive.

Objective: This study aimed to further elucidate the urinary metabolic profile of the plasticizer di(2-ethylhexyl) terephthalate (DEHTP) in search of probably additional biomarkers of exposure.

Materials and methods: Urine samples of an oral low-dose volunteer study were analysed by HPLC-Q-Orbitrap-MS combined with a commercial data mining software. Metabolite identification was based on isotopic pattern, accurate masses of product ions and excretion profiles.

Results: Nine phase I metabolites of DEHTP were tentatively identified by HPLC-Q-Orbitrap-MS. Four previously described, side chain oxidized monoester metabolites were confirmed in all samples. In addition, five previously unknown downstream metabolites were tentatively identified.

Discussion and conclusion: The excretion profiles obtained by HPLC-Q-Orbitrap-MS were in good agreement with quantitative HPLC-QqQ-MS data. For the newly discovered metabolites, plausible excretion profiles, similar to the ones of the known metabolites, were obtained. The presented approach proved to be successful for metabolite screening in urine samples after low-dose exposure and will be applied in future human metabolism studies for a fast, reliable and cost effective identification of specific biomarkers of exposure.

Keywords:

• Human biomonitoring
• metabolite screening
• di(2-ethylhexyl) terephthalate
• LC-HRMS
• Orbitrap
• biomarkers of exposure

Disclosure statement

The authors report no conflicts of interest.

Copyright notice

Figure 2 and Supplemental materials 3a–c partially reproduced from Arch Toxicol. (2016) 90: 1659–1667, “Figure 3: Urinary excretion kinetics for specific DEHTP metabolites in μg/L (left column) and creatinine adjusted concentrations (right column); continuous data of three volunteers” with friendly permission from Springer (License Number 4152450080552); © Springer-Verlag Berlin Heidelberg 2016.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.