Simultaneous determination of four sulfur mustard-DNA adducts in rabbit urine after dermal exposure by isotope-dilution liquid chromatography-tandem mass spectrometry

Sulfur mustard (SM) is a classic vesicant agent, which has been greatly employed in several wars or military conflicts. The most lesion mechanism is its strong alkylation of DNAs in vivo. Until now there are four specific DNA adducts of SM identified for further retrospective detection, i.e., N7-(2-hydroxyethylthioethyl)-2′-guanine (N7-HETEG), bis(2-ethyl-N7-guanine)thioether (Bis-G), N3-(2-hydroxyethylthioethyl)-2′-adenine (N3-HETEA) and O6-(2-hydroxyethylthioethyl)-2′-guanine (O6-HETEG), respectively. Here, a novel and sensitive method of isotope-dilution ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combining with solid phase extraction was reported for the simultaneous determination of four SM-DNA adducts. A lower limit of detection of 2-5 ng L−1, and a lower limit of quantitation of 5-10 ng L−1 were achieved, respectively, and the recoveries ranged from 87% to 116%. We applied this method in the determination of four SM-DNA adducts in rabbit urine after dermal exposure by SM in three dose levels (2, 5, 15 mg kg−1), so as to investigate the related metabolic behavior in vivo. For the first time, in SM exposed rabbit urine, our results revealed the relative accumulation abundance of four SM-DNA adducts, i.e., 67.4% for N7-HETEG, 22.7% for Bis-G, 9.8% for N3-HETEA, 0.1% for O6-HETEG, and significant dose and time dependent responses of these SM-DNA adducts. The four adducts were detectable after 8 h, afterwards, their contents continuously increased, achieved maximum in the first two or three days and then gradually decreased till the end of one month. Meanwhile, the amounts of SM-DNA adducts were positively correlated with the exposure doses.