A low-cost microfluidic paper-based analytical device (µPAD) with column chromatography preconcentration for the determination of paraquat in vegetable samples

Abstract

The objective of this work was to develop a simple microfluidic paper-based analytical device (µPAD) for the determination of paraquat. The µPAD was simply and rapidly made by dipping chromatography paper in melted paraffin. It was observed that the contact angle of the hydrophobic channel was 105.3 ± 4.4°. The analysis of paraquat was based on the reaction of paraquat in basic medium with sodium dithionite, giving the blue radical ions on the test zone. Measurement was made by taking photographs and measuring the red color intensity using the ImageJ program. Under the optimized conditions, the working range was determined to be 1.24–20.00 mg/L, LOD and LOQ were 1.24 and 4.13 mg/L with RSD for intraday and interday precision of 8.28% and 17.00%, respectively. The proposed µPAD device was applied for paraquat determination in several types of vegetable samples giving recovery of 89.9–104.9%. The results were not significantly different from spectrophotometry at the 95% confidence level.