Droplet-enhanced microspectrometry for trace level hexavalent chromium detection

摘要

This paper reports a droplet-enhanced microspectrometry system for quantitative detection of trace level hexavalent chromium (Cr[VI]) in water. A flow-focusing droplet (FFD) chip is proposed as the reaction and colorimetric cell. Two inherent mechanisms within droplet microfluidics are utilized to enhance the absorbance: (1) droplet compartmentalization to reduce the dispersion and (2) reflection at water/oil interface to increase the effective path length. A 15-fold enhancement in absorbance has been experimentally validated as compared to that without droplet. For Cr(VI) detection, a limit of detection (LOD) down to 7 μg L^{-1(0.14 ppb) was achieved.}