Novel paper-based microfluidic cassette for 2D paper chromatography and paper spray mass spectrometry (PS-MS) for drug metabolism analysis in urine

This paper presents a novel paper-based microfluidic cassette for 2D paper chromatography and paper spray mass spectrometry (PS-MS) for drug metabolism analysis in urine. The microfluidic device is composed of a 3D printed cassette and a special designed paper-based microfluidic platform. The 3D printed cassette is with delicate microstructures and channel for well dispersing the operation solution. Embedded microelectrodes for paper spray are also produced in the cassette with conductive polymer. The urine sample is directly applied to the sample trench and then separated and concentrated using a 2D paper chromatography technique. To further improve the performance of the paper-based microfluidic system, several special designs including a tip contact for uniform developing solution dispersion, several sacrificial wings for sample smear elimination and sculpted holes for electrical isolation during paper spray ionization. Results shows that the developed system can detect the secreted species including caffeine, vitamin B6 and pyridoxinal (metabolite of Vitamin B2) in urine in two-hours after taking Vitamin B complex tablet.