A single step test card for field screening of pesticide residues in vegetables based on simultaneous inhibition and reaction of cholinesterase was previously proposed. Here, favorable conditions to immobilize cholinesterase on filter paper for bulk production of this test card were developed. An amount of 28 mL of 6 U/mL cholinesterase solution was sprayed onto a filter paper sheet (210 mm × 297 mm) with speed of mL/s. | Journal of Science and Technology 54 (4A) (2016) 189-196 CHOLINESTERASE IMMOBLIZATION FOR LARGE-SCALE PRODUCTION OF HIGH SENSITIVE TEST CARDS FOR RAPID DETECTION OF ORGANOPHOSPHORUS AND CARBAMATE PESTICIDES IN AGRICULTURAL PRODUCTS Do Bien Cuong*, Cao Ngoc Tan School of Biotechnology and Food Technology, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Hanoi * Email: Received: 15 August 2016; Accepted for publication: 6 October 2016 ABSTRACT A single step test card for field screening of pesticide residues in vegetables based on simultaneous inhibition and reaction of cholinesterase was previously proposed. Here, favorable conditions to immobilize cholinesterase on filter paper for bulk production of this test card were developed. An amount of 28 mL of 6 U/mL cholinesterase solution was sprayed onto a filter paper sheet (210 mm × 297 mm) with speed of mL/s. After incubation at -20 ◦C for 60 min, enzyme coated-papers were dried at 60 ◦C for 30 minutes and stacked on indicator and substratecoated papers. The stack was cut into 10 mm × 10 mm-sized pieces for depositing on metallised polyester film sheets. Then another metallised film which holed 5 mm diameter holes was placed on the paper pieces, and 15 mm × 15 mm reaction windows were made by heat pressing. The developed test card’s detect limit by naked eyes ranged between and ppm of organophosphorus pesticides. This high sensitive test card provides a useful tool for detection of toxic organophosphorus and carbamate compounds in agricultural products, food and environment with cost-effective, minimized reagent consumption, and simple operation. Keywords: bromothymol blue, cholinesterase, pesticide, rapid detection, test card. 1. INTRODUCTION The detection of organophosphorus and carbamate pesticides is crucial in food analysis, because of the presence of these compounds in agricultural products and food is a serious threat to consumers’ health [1, 2]. So .
