Acid phosphatase/glucose oxidase-based biosensors for the determination of pesticides

✍ Scribed by Franco Mazzei; Francesco Botrè; Claudio Botrè

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 634 KB
• Volume: 336
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/s0003-2670(96)00378-9

✦ Synopsis

This work presents new amperomettic bienzymatic bioelectrodes for the determination of organophosphorus and carbamic acid type pesticides. Two different kinds of bienzymatic bioelectrodes are presented: a classical bienzymatic electrode, obtained by physicochemical immobilization of purified acid phosphatase (AP) and glucose oxidase (GOD) on the tip of an amperometric H202 electrode; and a hybrid biosensor, in which AP has been employed in the form of a thin layer of potato (Solanum tuberosum) tissue, endowed with a high content of enzyme activity. Both the biosensors can selectively detect glucose-6-phosphate (G6P), in the 5.0 x 1 O-5-1 .2x lo-' M concentration range. Pesticides are detected, thanks to their high inhibition power towards AP, evaluated by adding the sample stepwise to a buffered solution of G6P, and recording the corresponding current change. The detection limit is therefore a function of the type of pesticide, but it can be as low as 1 pg 1-l in the case of organophosphorus compounds. The detection limit is generally higher for carbamates, as a consequence of their weaker inhibition power towards acid phosphatase. Both bioelectrodes presented comparable values of the main physicochemical and analytical parameters evaluated for assessing their overall performance; nonetheless the plant tissue based bioelectrode exhibited a longer shelf life and a better reliability of the amperometric results.