Simple, Affordable Distance-Based Paper Analytical Device for the Quantitative Perfluorooctane Sulfonate Detection in Drinking Water and Beverage Samples

The emerging global concern over contamination of water supplies and food samples with per- and polyfluoroalkyl substances (PFAS) emphasizes the need to develop simple and cost-effective analytical methods for their monitoring. This article introduces the distance-based paper analytical devices (dPADs) for the detection of perfluorooctanesulfonate (PFOS) levels in consumable samples. This method leverages the oxidative decomposition of PFOS to deplete the generated hydroxyl radicals (•OH) from silver nanoparticles (AgNPs) and hydrogen peroxide (H2O2), which subsequently reduces the oxidation reaction of 3,3',5,5'-tetramethylbenzidine (TMB) to form oxidized TMB (oxTMB) on the paper substrate. Accordingly, PFOS levels can be quantified through changes in the uncolored distance length observable by the naked eye. Additionally, the utilization of the designed hydrophobic wax lines in the delay channel of the dPAD sensor enhances PFOS detection. The sensor exhibits a linear range of 3.0-15.0 ng L-1 (R2 = 0.9972) with a detection limit (LOD) of 3.0 ng L-1. The assay shows excellent accuracy and precision in monitoring PFOS in drinking water and beverage samples, with the recoveries ranging between 95.0 and 107.5% and the highest RSD of 7.89%. Similarly, the results obtained from our method are consistent with those of the high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) method, as confirmed by a 95% confidence level in t-test analysis. Notably, to the best of our knowledge, this is the first demonstration of the dPAD technique for PFOS detection, showing an effective and promising approach for real-world applications. Furthermore, the method is cheaper and easier to use than previous methods that rely on expensive instruments and require skilled personnel to operate them. Overall, the developed dPAD sensor has great potential as an instrument-free analytical technique for sensitive PFOS monitoring in water and beverage samples, enabling rapid assessment of food quality in both resource-limited settings and developing countries.