ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

A new fluorimetric method for determination of submicrogram amounts of cholinesterase inhibitors

J. Matoušek, J. Fischer, and J. Cerman

The Antonín Zápotocký Military Academy, Brno

Abstract: A highly sensitive method for determining organophosphorus compounds on the base of inhibition of choline esterase is described. Indoxyl acetate is used as a substrate, the reaction index being the change in fluorescence at time АФ/At. As preparation of choline esterase a lyophilised horse blood plasm was used. The optimum pH of the enzymatic hydrolysis is at 7.4 — 7.6 (a spontaneous hydrolysis at this pH and 25 °C does not take place). Km of indoxyl acetate at pH 7.6 and 25 °C is 6 . 10^-4 м. The rate of the enzymatic hydrolysis increases linearly with concentration of choline esterase. The relative standard deviation for the choline esterase determination s = ± 1.5 %. The sensitivity of determination for O-isopropylmethanenuorophosphonate 1.4 . 10^-7mg/ml;O-pinacolylmethanenuorophosphonate 1.10^-7 mg/ml;O-ethyl-N,N-dimethylamidocyanophosphate 1.6 . 10^-7 mg/ml; O,0'-diisopropylrluorophosphate 1.6 10^{- 5} mg/ml; O,O'-diethyl-O''-nitrophenylphosphate 2.8 10^-7 mg/ml; 0-ethyl-S-2-dimethylaminoethylmethanethiophosphonate 2 . 10^-5 mg/ml. Determination time 12—15 minutes.

Full paper in Portable Document Format: 223a184.pdf (in Czech)

Chemical Papers 22 (3) 184–189 (1968)