A centrifugal microanalysis system for the determination of nitrite and hexavalent chromium

A centrifugal microanalysis system using spectrophotometric detection has been developed for the determination of nitrite and chromium VI. The system was designed to illustrate the potential of centrifugal microfluidic systems for on-site (field) analysis of waters. The performance was significantly better than manual/visual field test systems and approaches that of bench top systems with detection limits of 0.008 mg L−1 NO2−-N and 0.03 mg L−1 Cr6+. The system used pre-loaded solid reagents on the disc, providing ease of use, and could process up to 24 samples simultaneously. Precision was enhanced by the use of a multiwavelength ratiometric blank estimation technique.