A Green Analytical Methodology for Detecting Adulteration in Automotive Urea-SCR Products Using Microfluidic-Paper Analytical Devices

The application of urea-based selective catalytic reduction products (i.e., Urea-SCR) provides a NOx and, therefore, minimizes pollution emissions from vehicles fueled by diesel. Such can be easily found in the market; however, they are often susceptible to adulteration, mainly terms urea content and dilution with non-mineralized water. In this study, we propose simple, low-cost, disposable, straightforward paper-based microfluidic device for quality-control Urea-SCR first time quantifying water hardness simultaneously via colorimetric reactions using small volume sample. 4-(dimethylamino)benzaldehyde Eriochrome T were used as indicators determination, respectively. Each reagent (1.5 µL) was combined 6 µL sample analysis, contributing an expressive waste generation. Digital images µPAD obtained, linear relations between color intensity Ca2+ Mg2+ concentrations range 0.2 1.0% 0.1 3.5 mmol L−1 obtained correlation coefficient higher than 0.99. Recovery experiments employed evaluate accuracy methodology, revealing suitable values 91.5 115%. Brazilian samples acquired different distributors submitted proposed procedure its applicability. devices enables quality control high accuracy, portability, low consumption reagents, no generation toxic residues; thereby green analytical chemistry field.