A colorimetric microfluidic paper-based analytical device for sulfonamides in cow milk using enzymatic inhibition

To increase milk production, antibiotics are administered to animals to provide weight gain and to prevent or treat diseases. The inappropriate use of these substances can lead to antibiotic resistance and allergic reactions and toxic effects to milk consumers. We describe the development of a simple, fast, portable, and low-cost microfluidic paper-based analytical device (mu PAD) to quantify sulfonamides in milk using the inhibition of the colorimetric reaction between carbonic anhydrase (CA) and 4-nitrophenyl acetate. The main advantages presented by the mu PAD include reproducible batch production, simple application, and precise analysis without previous treatment. The mu PAD displayed good linearity (R-2 >= 0.986) in a wide range of sulfonamides in milk (2.5 to 40.0 mu mol L-1), being selective for the drugs even in a highly complex matrix. We expect that this device allows in situ monitoring of milk quality, reducing the prejudicial conditions associated with high concentrations of sulfonamides in milk.

Automated summary

In order to detect sulfonamides in milk, a simple and portable microfluidic paper-based analytical device (mu PAD) was developed for precise analysis without the need for pretreatment. This device has good linearity and selectivity, potentially allowing for on-site monitoring of milk quality to reduce adverse conditions associated with high concentrations of sulfonamides.