A miniature and efficient colorimetric system assisted by the microplasma jet array for Cr (VI) detection.

Microplasma jet (MPJ), serving as excitation sources in miniaturized systems, has been widely used for contaminant detection. However, the employment of the MPJ is conditioned due to the limit generation of the radicals. Here, a novel 4-channel microplasma jet array (MPJA) is designed for 3,3,5,5-tetramethylbenzidine (TMB) rapid oxidation without oxidizing reagents and catalysts. The jet array, generated from a ceramic tube, allows direct contact with the sample. A colorimetric system containing the MPJA has been developed for the detection of hexavalent chromium. Compared to the MPJ, the employment of MPJA significantly makes the detection system effective and sensitive. Under optimal operating condition, the system exhibits a linear response for Cr (VI) detection within the range of 0.3-1.2 μmol L-1, with a detection limit (LOD) of 0.11 μmol L-1. The practicality of the system is validated through the analysis of real-world samples. The system can be packed into a case with 40 cm in length, 30 cm in width and 30 cm in height. The power consumption is 0.052 W. The system provides a potential method for samples determination in emergency.