A metal ion-regulated colorimetric sensor array: discriminating Chinese Baijiu from other beverages

The complex and huge Chinese Baijiu market is in need of a quick and accurate detection method to achieve quality control. Herein, we provide a Baijiu colorimetric sensor array based on a metal ion-regulated Au NP aggregation, which can achieve a correct classification of 16 Baijiu samples with different flavors. This is the first time metal ions (Mg2+, Pb2+, Fe2+, and Fe3+) are employed to adjust the microenvironment of a Baijiu colloid for regulating the aggregation of Au NPs in a sensor array. The RGB (the red, green and blue color models) values of the final aggregation of Au NPs were captured as the optical signal for further data processes. The provided Baijiu identification system shows outstanding discrimination performance using pattern recognition and neural networks. Astonishingly, selectivity experiments indicate that our array is able to completely distinguish Baijiu samples from other drinks (e.g., tea samples and a mixture of ethanol and water), showing great potential in practical detection.