DETERMINATION OF THE MAIN HYDROLYSIS PRODUCTS OF ORGANOPHOSPHORUS NERVE AGENTS, METHYLPHOSPHONIC ACIDS, IN HUMAN SERUM BY INDIRECT PHOTOMETRIC DETECTION ION CHROMATOGRAPHY

For the verification of the use of chemical warfare agents (CWA), sari n, soman and VX, a simple rapid and accurate method which allows us to simultaneously determine their degradation products, isopropyl methyl phosphonic acid (IPMPA), pinacolyl methylphosphonic acid (PMPA), ethyl methylphosphonic acid (EMPA) and methylphosphonic acid (MPA), in huma n serum, was explored by indirect photometric detection ion chromatogr aphy (IPD-IC) which employs an anion-exchange column. IC analysis was performed after sample preparation with an Ag+-form cation-exchange re sin cartridge, and the four methylphosphonic acids could be separated well. The proposed conditions are as follows: eluent, 0.5 mM phthalic acid-0.1 mM Tris (hydroxymethyl) aminomethane-5% acetonitrile; flow-ra te, 1.0 ml/min; temperature, 50 degrees C; UV detector, 266 nm. All fo ur methylphosphonic acids were eluted within 30 min with hardly any di sturbance by impurities in the serum. Linear calibration curves were o btained for MPA, EMPA and IPMPA in the concentration range from 50 ng/ ml to 1 mu g/ml and for PMPA from 100 ng/ml to 1 mu g/ml. The relative standard deviation for the methylphosphonic acids ranged from 3.8 to 6.9% at 500 ng/ml and the detection limits were 40 ng/ml for MPA, EMPA and IPMPA and 80 ng/ml for PMPA. The method would be suitable for ana lysis of human serum samples. (C) 1997 Elsevier Science B.V.