High Throughput Analysis of Di‐(2‐Ethylhexyl)phthalate Metabolites in Urine for Exposure Assessment

Abstract

In order to assess exposure, we developed high throughput analysis of di‐(2‐ethylhexyl)phthalate (DEHP) metabolites in urine using an on‐line solid phase extraction–liquid chromatography/tandem mass spectrometry (on‐line SPE–HPLC–MS/MS) method. The metabolites were detected in the negative mode by select reaction monitoring at low nanogram per milliliter levels. Repeatability and reproducibility of the methods was checked by analyzing spiked urine. The results, expressed as relative standard deviation (RSD%), varied from 0.8 to 6.9. The recoveries were above 85.8%. Three metabolites of DEHP were detected with the levels from 9.5 to 320.8 ng mL⁻¹ for mono‐(2‐ethyl‐5‐hydroxyhexyl)phthalate (VI), from 13.9 to 187.5 ng mL⁻¹ for mono‐(5carboxy‐2‐ethylpentyl)phthalate (IX), and from ND to 13.9 ng mL⁻¹ for mono‐(2‐ethylhexyl)phthalate (MEHP). The concentration levels of VI and IX were detected higher than MEHP. The frequencies of VI and IX were 100%. The proposed method introduces the possibility of determining these metabolites within 8 min (including sample preparation time), while also increasing sensitivity and reducing amounts of sample and solvent required.

Keywords:

• DEHP metabolites
• HPLC‐MS/MS
• Exposure assesment

Acknowledgment

This study was supported in part by a Grant in‐AID from the Ministry of Health and Welfare and the Ministry of Education, culture, sports, science, and technology, Japan.