A centrifugal microfluidic platform integrating monolithic capillary columns for high-throughput speciation of chromium

In this work, a centrifugal microfluidic platform with multiple solid phase extraction (SPE) units has been developed and successfully applied to separate Cr(VI) and Cr(III) with high throughput, followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. Monolithic capillary columns, prepared by polymerization of N-(beta-aminoethyl)-gamma-aminopropyltriethoxysilane (AEAPTES) and tetraethoxysilane (TEOS), were integrated on a PDMS chip and used as the media for the selective extraction of Cr(VI). The aqueous solutions on the chip were driven by the centrifugal force produced by a centrifugal motor, so that high-throughput SPE is achieved by processing multiple samples simultaneously. The adsorption and elution conditions of Cr(VI) onto the monolithic capillary column, and the rotation speed of the centrifugal motor were well studied. The feasibility of the proposed protocol was validated by certified reference materials and real water samples. In contrast to the traditional speciation analysis procedure, the species separation of eight samples can be finished within 10 min on the established centrifugal microfluidic platform. This device possessing the advantages of portability and simplicity provides a potential application for field sampling and pretreatment.