Determination of organophosphate and carbamate pesticides using a cobalt phthalocyanine-modified carbon paste electrode and a cholinesterase enzyme membrane

✍ Scribed by Petr Skládal

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 467 KB
• Volume: 252
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(91)87190-i

✦ Synopsis

An amperometric biosensor for the detection and determination of organophosphate and carbamate pesticides is based on a cobalt phthalocyanine-modified carbon paste electrode covered with a cholinesterase enzyme membrane. The electrode poised at +400 mV (vs. Ag/AgCI/3 M KCI) oxidizes thiocholine formed by butyrylthiocholine hydrolysis in the glutaraldehyde-cross-linked cholinesterase layer. The activity of cholinesterase is non-competitively inhibited in the presence of pesticides. A linear relationship exists between the relative decrease in steady-state current after the addition of a sample and the inhibitor concentration. This method of evaluation allows the repetitive use of an enzyme membrane; twenty analyses can be carried out with a single cholinesterase membrane. The sensitivity varies from 0.181 (Hostaquick) to 0.00136 s-' g-' I (Seedox); detection limits are 0.3 and 80 mg i-', respectively, for these two pesticides. The determination of eleven pesticides is demonstrated.