Quantitation of Fluoride Ion Released Sarin in Red Blood Cell Samples by Gas Chromatography-Chemical Ionization Mass Spectrometry Using Isotope Dilution and Large-Volume Injection

Abstract

A new method for measuring fluoride ion released isopropyl methylphosphonofluoridate (sarin, GB) in the red blood cell fraction was developed that utilizes an autoinjector, a large-volume injector port (LVI), positive ion ammonia chemical ionization detection in the SIM mode, and a deuterated stable isotope internal standard. This method was applied to red blood cell (RBC) and plasma ethyl acetate extracts from spiked human and animal whole blood samples and from whole blood of minipigs, guinea pigs, and rats exposed by whole-body sarin inhalation. Evidence of nerve agent exposure was detected in plasma and red blood cells at low levels of exposure. The linear method range of quantitation was 10-1000 pg on-column with a detection limit of approximately 2-pg on-column. In the course of method development, several conditions were optimized for the LVI, including type of injector insert, injection volume, initial temperature, pressure, and flow rate. RBC fractions had advantages over the plasma with respect to assessing nerve agent exposure using the fluoride ion method especially in samples with low serum butyrylcholinesterase activity.

Prophylaxis with human serum butyrylcholinesterase protects Göttingen minipigs exposed to a lethal high-dose of sarin vapor

“…Blood was separated into erythrocyte and plasma fractions by centrifugation and the amount of GB bound to each fraction was determined by measuring regenerated GB using gas chromatography/mass spectrometry (GC/MS) as described [24,29].…”

“…All values are mean ± S.E.M. Blood was separated into erythrocyte (solid bars) and plasma (hatched bars) fractionsby centrifugation and GB was regenerated from 0.1-0.25 g of each sample as described[29].…”

Physiologically Based Pharmacokinetic Modeling of Chemical Warfare Agents

“…This technique has not yet been applied systematically for kinetic modeling of CWNA exposures in guinea pigs. Recently, a method for regenerating GB from blood and tissue has been developed and validated in rat, guinea pig, and pig models and provides a sensitive and quantitative means for estimating the kinetics of GB in blood (Jakubowski et al, 2004). This method is based on fluoride ion regeneration of the protein-bound agent.…”

Laboratory Analysis of Chemical Warfare Agents, Adducts, and Metabolites in Biomedical Samples

“…Another option is to improve the selectivity of the detector. Chemical ionization with ammonia as the reaction gas is a relatively soft ionization mode, which ensures a more selective detection of only compounds with sufficient proton affinity (Degenhardt et al, 2004;Jakubowski et al, 2004;Holland et al, 2008;Solano et al, 2008). Another more expensive but recently affordable option is to use a high-resolution R-MS or MS-MS instrument, which can nerve AgentS VII.…”