Microfluidic Paper based Analytical Device (µpads) for Analysis of Benzoat Acid in Packaged Beverages

Microfluidic Paper-based Analytical Devices (μPADs) are a simple analytical platform that satisfy combination of low cost, portability, and ease-to-use with selectivity, sensitivity, and accuracy. In this experiment, the μPADs devices are prepared using a chromatographic paper and designed at appropriate pattern prior to printing by mean of a solid ink (wax) printer to produce hydrophobic barriers and hydrophilic channels. Then, the μPADs are heated at 120°C for 3 min to allow a wax penetrates in the both side of a paper. The resulted μPADs are used for the detection of benzoic acid through alkalimetry principle. For this purpose, the devices are implanted with 5M NaOH in the detection zone and a 2% phenolphthalein indicator in the sample zone before dried in open air. When the devices have dried, the μPADs are ready to be used to detect benzoic acid. To avoid color interferences, the samples are distilled before introduced to the sample zone for quantitative detection. The result soft the color changes can be immediately seen by naked eye, and their intensities are quantified by the Image J software. Excellent linearity is achieved in the range of benzoic acid concentration of 20-120 ppm with the linear equation of Y = 0.0102 x + 0.0077 and the correlation coefficient (R²) of 0.9999. The optimized μPADs devices are successfully applied to the quantitative analysis of benzoic acid in the 5 kinds of commercially packaged beverages. There is no significantly different of the analytical results obtained by the µPADs in comparison to the spectrophotometric method. Overall, the results obtained in this study indicate that the μPADs devices are a reliable tool for high throughout and on-site determination of benzoic acid content in commercial drinks.