Evidence of sulfur mustard poisoning by detection of the albumin‐derived dipeptide biomarker C(‐HETE)P after nicotinylation

Abstract

Sulfur mustard (SM, bis[2-chloroethyl]-sulfide) is a banned chemical warfare agent that was frequently used in recent years and led to numerous poisoned victims who developed painful erythema and blisters. Post-exposure analysis of SM incorporation can be performed by the detection of human serum albumin (HSA)-derived peptides.HSA alkylated by SM contains a hydroxyethylthioethyl (HETE)-moiety bound to the cysteine residue C 34 yielding the dipeptide biomarker C(-HETE)P after pronasecatalyzed proteolysis. We herein present a novel procedure for the selective precolumn nicotinylation of its N-terminus using 1-nicotinoyloxy-succinimide. The reaction was carried out for 2 h at ambient temperature with a yield of 81%. The derivative NA-C(-HETE)P was analyzed by micro liquid chromatography-electrospray ionization tandem-mass spectrometry working in the selected reaction monitoring mode (μLC-ESI MS/MS SRM). The derivative was shown to be stable in the autosampler at 15 C for at least 24 h. The single protonated precursor ion (m/z 428.1) was subjected to collision-induced dissociation yielding product ions at m/z 116.1, m/z 137.0, and m/z 105.0 used for selective monitoring without any plasma-derived interferences. NA-C(-HETE)P showed a mass spectrometric response superior to the non-derivatized dipeptide thus yielding larger peak areas (factor 1.3 ± 0.2). The lower limit of identification corresponded to 80 nM SM spiked to plasma in vitro. The presented procedure was applied to real case plasma samples from 2015 collected in the Middle East confirming SM poisoning.

Alkylated glutamic acid and histidine derived from protein‐adducts indicate exposure to sulfur mustard in avian serum

“…In addition, the elaboration of CID conditions that also favor the generation of the internal [HETE] + -derived ion might provide beneficial perspectives improving the reliability of the adducts described. Furthermore, derivatization of adducts as already described for Cys(-HETE)Pro 25,26 and a butyrylcholinesterase-derived nonapeptide biomarker 27 might improve the value of the markers. The use of other proteases generating alkylated biomarker peptides might be an alternative approach as well.…”