Development and characterization of microchip electrophoresis pulsed amperometric detector-based soil pesticide analyser

The present study involved the fabrication and testing of a Microchip electrophoresis (MCE) device for pulse amperometry based detection of pesticides from their mixture. We were able to separate and then quantify three distinct types of insecticides, namely Chlorpyrifos, Imidacloprid, and Fipronil using on chip MCE followed by pulsed amperometric detection. All these results were obtained with an inhouse developed potentiostat cum controller unit with a detection time of only 15 min, employing a minimal sample size of 2 μL without any preconcentration or extraction procedure. The limit of detection (LOD) was calculated as 42.69 μM, 62.61 μM, and 71.14 μM or 14.96, 16.0 and 31.09 ppm, respectively for Chlorpyrifos, Imidacloprid, and Fipronil and their respective migration times as 536 ± 6.3 s, 484 ± 1.7 s, and 604 ± 3.5 s (n = 14). The sensitivity of detection was determined as 0.03 nA/μM for Chlorpyrifos, 0.0265 nA/μM for Imidacloprid, and 0.035 nA/μM for Fipronil. In addition, the efficacy of the produced microchip was confirmed by analysing soil extract spiked with known pesticides concentrations while the recovery percentage, representing a ratio of calculated concentration to spiked concentration multiplied by hundred was found as 84.3% (±9.4%) (n = 9). Thus, integrating microchip technology with the developed analytical instruments presents significant promise for practical field applications and the analysis of diverse analytes by way of creating a library where the migration coefficient and peak detection current are needed for any analyte which can be made cationic or anionic using a suitable buffer.