A sensitive high performance liquid chromatography–positive electrospray tandem mass spectrometry method for N7-[2-[(2-hydroxyethyl)thio]-ethyl]guanine determination

A simple, fast, sensitive and robust method for the determination of the sulfur mustard (SM) exposure biomarker–N7-[2-[(2-hydroxyethyl)thio]-ethyl]guanine (HETEG) was reported using high-performance liquid chromatography–positive electrospray tandem mass spectrometry (HPLC–ESI-MS/MS), working in multiple reaction monitor (MRM) mode. The method provided limit of detection of 0.330 ng/mL and lower limit of quantitation of 0.940 ng/mL. The method was linearly calibrated from 0.940 ng/mL to 587 ng/mL with precisions of 3.5–14.5%, and accuracies of 88–112%. The recovery varied from 102% to 118%. HETEG spiked in DNA hydrolytes isolated from the human whole blood was stable after five freeze/thaw cycles and 35-day frozen at −20 °C. For the exposed biological samples, alkylated DNA was isolated from SM-treated human whole blood, followed by DNA digestion and adducts enrichment, the resulting alkylation base was determined. By the procedure, the HETEG level in DNA hydrolytes isolated from the human whole blood exposure to 312 ng/mL SM was detected successfully.