Quantitative analysis of ethylene glycol in human serum by liquid chromatography-tandem mass spectrometry with p-toluenesulfonyl isocyanate derivatization.

Purpose: Ethylene glycol (EG) is a typical antifreeze compound and a significant analyte in forensic toxicology. Current EG analytical method for biological samples in forensic toxicology employ liquid chromatography-tandem mass spectrometry (LC-MS/MS), however, they exhibit low sensitivity and reliability. Therefore, in this study, we aimed to establish a highly sensitive, selective, and reliable EG assay system for human serum analysis using a hydroxyl derivatization-aided LC-MS/MS technique.

Methods: p-Toluenesulfonyl isocyanate (PTSI) was applied for precolumn derivatization of EG in human serum, to enhance the sensitivity of LC-MS/MS for EG detection.

Results: The optimal derivatization conditions were 200 µL/mL PTSI in acetonitrile at 25 °C for 10 min. A highly sensitive and reliable LC-MS/MS detection of EG in human serum was achieved, with the calibration curve exhibiting a good linearity (r > 0.999, 10-1000 µg/mL of EG). The proposed PTSI-derivatization-LC-MS/MS method exhibited high reliability (1.4-1.8%) for the intra-day and inter-day repeatability (%RSD), and accuracy (96.7-102.4%), with the limits of detection and quantification in human serum being 0.023 µg/mL (S/N = 3) and 0.077 µg/mL (S/N = 10), respectively.

Conclusions: A novel PTSI derivatization-aided LC-MS/MS method was developed, offering a highly sensitive, selective, and reliable analytical tool for EG quantification in human serum for forensic toxicology applications.