Stabilization and gas chromatographic analysis of the four stereoisomers of 1,2,2-trimethylpropyl methylphosphonofluoridate (soman) in rat blood

• Published in: Analytical biochemistry Vol. 151; no. 2; pp. 242 - 253
• Main Authors: Benschop, Hendrik P., Bijleveld, Eric C., Otto, Matthijs F., Degenhardt, Carla E.A.M., Van Helden, Herman P.M., De Jong, Leo P.A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.12.1985
• Subjects: 1,2,2-[U- 2H]trimethylpropyl methylphosphonofluoridate; 1,2,2-trimethylpropyl methylphosphonofluoridate; aliesterase; Animals; chiral; Chromatography, Gas - methods; Deuterium; Drug Stability; gas chromatography; Hydrogen-Ion Concentration; Indicators and Reagents; Kinetics; phosphorylphosphatase; Rats; soman; Soman - blood; Soman - chemical synthesis; Stereoisomerism; aliesterase; phosphorylphosphatase; 1,2,2-[U- 2H]trimethylpropyl methylphosphonofluoridate; chiral; soman; 1,2,2-trimethylpropyl methylphosphonofluoridate; gas chromatography
• ISSN: 0003-2697; 1096-0309
• DOI: 10.1016/0003-2697(85)90172-1

A method for the stabilization and gas chromatographic analysis of the four stereoisomers of C(±)P(±)-1,2,2-trimethylpropyl methylphosphonofluoridate (C(±)P(±)-soman) in rat blood samples is described. Satisfactory stabilization of all four stereoisomers is obtained by (i) acidification of the blood sample to pH 4.2 at 0°C, to stabilize the C(±)P(+) isomers, (ii) addition of aluminum ions (2.5 m m) for complexation of fluoride ions, which prevents regeneration of C(±)P(−)-soman by free fluoride ions from soman-inhibited aliesterase, and (iii) addition of 2,2-dimethylpropyl methylphosphonofluoridate in order to occupy covalent binding sites for C(±)P(−)-soman. The stereoisomers of soman and internal standard are extracted from the blood-stabilizing buffer mixture with a Sep-Pak C 18 cartridge and are subsequently eluted with ethyl acetate with overall extration recoveries of 52 ± 8%. The four soman stereoisomers are resolved and analyzed on a wide-bore capillary Chirasil Val column, synthesized, and coated in house, which also resolves the internal standard C(±)P(+)-1,2,2-[U- 2H]trimethylpropyl methylphosphonofluoridate from C(±)P(±)-soman. Alternatively, the gas chromatographic analysis can be performed on a wide-bore capillary Chirasil Val column, identical with the commercially available Chirasil Val column, when combined in series with a Carbowax 20M column. This system resolves the four stereoisomers of soman and the internal standard C(−)P(+)-1,2,2-trimethylpropyl [U- 2H]methylphosphonofluoridate. Using an alkali flame ionization detector, the detection limit of our procedure is ca. 250 pg soman isomer/blood sample.