An optical nose based on array of metal-doped carbon dots for identification of hazardous amines and assessing meat freshness

There is an obvious pressing demand for the sensitive and rapid, identification of toxic gases as environmental concerns. In this study, a facile approach for the detection and identification of amine solvents is reported. A colorimetric sensor array composed of different ninhydrin-mediated transition metal-doped carbon dots (TMCDs), deposited on a paper substrate, could sniff the odor of 29 different amines and accomplish their accurate identification. This analytical device generates a unique response pattern for each amine. Modeling the response data of the sensor array by linear discriminate analysis yields a discrimination accuracy of 94 % for the amines. Also, this method allows rapid quantification of ethylamine and isopropylamine in the concentration ranges of 0.008–1600 ppm and 0.05–828 ppm with detection limits of 1.4 ppb and 39 ppb, respectively, which are well below the immediately dangerous to life or health (IDLH) limit concentration for these amines. Interestingly, this sensor array provides discrimination between the isomers of some amines. Moreover, binary and ternary mixtures of amine solvents could be well recognized with this sensor. The application of the sensor array was tested for the assessment of the quality and freshness of some kinds of meat.