Multivariate Optimization of Operational Parameters in Microfluidic Paper-Based Analytical Devices for the Determination of Organophosphate and Carbamate Pesticides.

The aim of this study is to employ a response surface methodology (RSM) to optimize experimental parameters in microfluidic paper-based analytical devices (µ-PADs). The independent parameters include concentrations and volumes of acetylcholinesterase, acetylthiocholine iodide, and 5,5-dithiobis-(2-nitrobenzoic acid). Their effect on mean color intensity was tested and optimized. From the analysis of variance, high regression and fitting values were obtained between the experimental and RSM predicted mean color intensity. Under optimum conditions, satisfactory linearity (R2 > 0.9990) in the range of 0.25–16 mg/L was obtained for the studied pesticides. The limit of detection (LOD) varies from 0.13 to 0.27 mg/L; high precision (RSD of 3.8–8.0%), reproducibility (RSD of 7.2–11.0%), and recovery (78–97%) were achieved. The RSM approach has been demonstrated to be more efficient than the traditional approach. It resulted in a µ-PAD system with less amount of reagent usage and better LOD compared with a univariate approach. [ABSTRACT FROM AUTHOR]