Determination of alkyl methylphosphonates and methylphosphonic acid by capillary electrophoresis with a diode-array spectrophotometric detector

Method of capillary electrophoresis with a diode-array detector was used to study the conditions of the separation of three alkyl methylphosphonates and methylphosphonic acid, hydrolysis products of nerve agents. The optimal conditions providing their separation and determination are reported (background electrolyte based on 100 mM boric acid with the addition of 10 mM of phenylphosphonic acid (pH 6.0); voltage +30 kV, detection wavelength 210 nm, electrokinetic introduction of the sample (10 kV, 10 sec), separation time below 10 min). Calibration curve for all the compounds was linear in the concentration range 0.05–1.0 mg/mL, the correlation coefficient was 0.999 in all cases. The procedure was tested for river and ground waters containing a mixture of isopropyl, isobutyl, pinacolyl methylphosphonates and methylphosphonic acid. Relative standard deviations of the migration times under the conditions of the repeatability of the results lie in the range 1.9–2.7% (n = 5), the relative standard deviation of the reduced peak areas vary from 1.2 to 7.0%.