During the United Nations fact-finding mission to investigate the alleged use of
chemical warfare agents in the Syrian Arab Republic in 2013, numerous tissues from a deceased female victim, who had displayed symptoms of
cholinergic crisis, were collected. The Organisation for the Prohibition of Chemical Weapons (OPCW) authorized two specialized laboratories in the Netherlands and Germany for forensic analysis of these samples. Diverse modern mass spectrometry (MS)-based procedures in combination with either liquid chromatography (LC) or gas chromatography (GC) separation were applied. A variety of biotransformation products of the
nerve agent sarin was detected, including the hydrolysis product O-
isopropyl methylphosphonic acid (
IMPA) as well as covalent
protein adducts with e.g.,
albumin and human
butyrylcholinesterase (hBChE).
IMPA was extracted after sample acidification by solid-phase extraction and directly analyzed by LC-tandem-MS with negative electrospray ionization (ESI).
Protein adducts were found, either by
fluoride-induced reactivation applying GC-MS techniques or by LC-MS-based detection after positive ESI for proteolyzed
proteins yielding phosphonylated
tyrosine residues or a specific phosphonylated hBChE-derived nonapeptide. These experimental results provided unambiguous evidence for a systemic intoxication and were the first proving the use of
sarin in the ongoing bellicose conflict. This scenario underlines the requirement for qualified and specialized analytical laboratories to face repeated violation of the Chemical Weapons Convention.