Preparation of AChE immobilized microspheres containing thiophene and furan for the determination of pesticides by the HPLC-DAD method

Abstract

In this study, acetylcholinesterase (AChE) enzyme immobilized polymeric microspheres were prepared to detect the dichlorvos (DDVP: 2,2-dichlorovinyl dimethyl phosphate) and the chlorpyrifos (O, O-Diethyl 0-3,5,6-trichloropyridin-2-yl phosphorothioate) pesticides. To produce polymeric supports, tris(2-aminoethyl)amine polystyrene (2AEPS) was reacted with thiophene carboxaldehyde and its derivatives; and 2AEPS was also reacted with furaldehyde and its derivatives. A total of six different ligands were synthesized (2AEPS-Tio, 2AEPS-5-CH(3)Tio, 2AEPS-5-NO2 Tio, 2AEPS-Fur, 2AEPS-5-CH(3)Fur, 2AEPS-5-NO(2)Fur). Polystyrene's spherical porous structure having large surface area and aldehyde groups were modified to enhance the efficiency of enzyme immobilization. In terms of the number of times it can be reused, the highest relative activity was found to be with 2AEPS-Tio-AChE at 71.28% after 10 cycles. HPLC-DAD system was used for detection of pesticides. For this purpose, the parameters which were thought to affect the response in HPLC-DAD analysis were optimized. Method validation was performed for pesticides. The decomposition reaction of the pesticide was followed by free and immobilized AChE enzyme using validated conditions. Using free AChE, the detection of limit (LOD) for DDVP and chlorpyrifos was found to be 2.57 mu g L-1 and 0.45 mu g L-1, respectively. When using immobilized AChE, the LOD values for DDVP and chlorpyrifos was obtained in the range of 0.42-0.75 mu g L-1 and 0.34-4.23 mu g L-1, respectively. (C) 2020 Elsevier B.V. All rights reserved.