Simultaneous measurement of six biomarkers of dichlorvos in blood by ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry.

A protocol was developed, via a data-dependent high-resolution tandem mass spectrometry (ddHRMS/MS), to detect six biomarkers of dichlorvos in its metabolites and blood adducts of butyrylcholinesterase and albumin without using standard synthetic peptides. Firstly, the adducts of dimethoxy phosphonate (DMP-BChE) and the aged adducts of methoxy phosphonate (MxP-BChE) were isoloated by immunomagnetic separation (IMS), and then digested to DMP-nonapeptide and MxP-nonapeptide by pepsin. The dichlorvos and its metabolites (Trimethyl phosphate, Dimethyl phosphate) were analyzed in the supernatant of IMS treatment after protein precipitation. The precipitate was digested by pronase to phosphorylated tyrosine (DMP-Tyr), which were quantified by ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry (UPLC-MS). The linearity of detector response of all biomarkers was studied in their respective ranges, and the correlation coefficients (R2) were all greater than 0.9981. The limits of detection (LOD) and limits of quantification (LOQ) were 0.2-10 ng/mL and 0.5-20 ng/mL, respectively. The recoveries of the six biomarkers were 78.6-110.0 %, matrix effect were 64.1-106.8 %. Inter- and intra-assay precision had coefficients of variation of ≤13.2 % and ≤9.7 %, respectively. In addition, MxP- BChE, DMP-Tyr, TMP, DMP and DDVP were detected in the blood of three cases who died from DDVP poisoning, but DMP- BChE was not detected in all of them, which may be caused by the instability of DMP- BChE and its easy aging to form MxP-BCHE.