The potentiometric determination of insecticides: Part I. Organophosphorus insecticides inhibiting cholinesterase

✍ Scribed by W.N. Dahl; Å.M.R. Holm; K.H. Schrøder

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 418 KB
• Volume: 93
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(77)80011-1

✦ Synopsis

IQcceived 22nd April 197i)

A potentiometric method for the determination of orgsnophosphorus irsecticides based on the inhibition of cholineste-is presented. The acetic acid formed by hydrolysis of ncctylcholinc is sensed by a &ass electrode in a weakly buffered svstem. The insecticide is incubated with cholinesterase for 1 h at 25°C or 35°C before addikon to the substrate_ The effc-zts of incubation time and temperature are discussed. The method is applied to the insecticides bromophas and dichlorvos. The detection limits are 2 x 1Oa M (7 ppb) for bromophos and 1 X lo-' M (22 ppb) for dichlorvos. The initial rates of hydrolysis decrease linearly up to 2 x lo-' M and 1 X 10% M, respectively.