PAPER-BASED TEST STRIP FOR PESTICIDE ANALYSIS

Abstract

A paper-based test strip for analysis of organophosphate (OPs) and carbamate (CBs) pesticide using enzyme inhibition acetylcholinesterase (AChE) has been developed. The device was constructed by immobilizing the AChE enzyme and Ellman's Reagent (DTNB) onto the detection zones of the paper devices. Biopolymers were employed for reagent coating and stabilizing to extend shelf life of the devices. In the absence of pesticides, the enzyme AChE catalyzed the formation of thiocholine (TC) that reacts with DTNB to produce a yellow product (TNB-). After incubation with organophosphate pesticide, the activity of AChE was inhibited and produced less TC, and hence, reduced yellow product. Color intensity was analyzed by scanning the picture and measuring the intensity using ImageJ software. The developed paper-based test strip can analyze OPs and CBs pesticides without complicated methods and expensive laboratory instrument. Excellent limits of detection were obtained for all four pesticide representatives. Limits of detection as low as 1.34 µg/mL, 1.21 ng/mL, 1.36 µg/mL and 1.48 ng/mL were detected for malathion, dichlorvos, carbaryl and carbofuran, respectively. The developed paper-based test strip can be successfully used to detect pesticide contamination in dried seafood product samples (dried fish, dried squid, and dried shrimp) and the results were validated with those obtained from the traditional method (LC-MS/MS). The DSP level obtained from the two methods were not significant difference at 95% confidence level (two tailed P>0.05) indicating the high accuracy of the developed paper-based test strip. Therefore, the developed test can be used as an alternative method for the analysis of OP and CB pesticides offering low cost, rapid and on-site analysis, without complicated laboratory instrument.

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