Construction Of Colorimetric Sensor Array Based On Dyes And Nanomaterials And Study Of Baijiu Visual Identification

Chinese Baijiu is a popular alcoholic beverage,which has a brewing history of thousands of years.With the development of the baijiu industry,the baijiu market has grown year by year,putting forward higher requirements for the quality control of baijiu.However,no matter in the production process or sales process of baijiu,there is a lack of on-site rapid identification and testing methods.At present,the commonly used methods for identification and detection of baijiu include sensory evaluation and instrumental analysis.The sensory evaluation method is greatly affected by individual subjective differences,and cannot detect a large number of samples at the same time;The instrumental analysis method requires expensive equipment and complex operation,so it is not suitable for real-time detection of baijiu.In recent years,the colorimetric sensor array detection method based on cross-response can visually detect different liquid or gas analytes by imitating taste and smell.What's more,it has been used to identify complex mixture recognition due to its simple preparation,low cost,and naked eye discernibility.In this study,dyes,Ag nanoparticles,Au nanoparticles and other nanomaterials with excellent properties were used to construct colorimetric arrays.Three schemes based on the colorimetric sensor array chip to quickly identify baijiu were designed to provide methods for on-site rapid detection of baijiu.Through the screening and characterization(TEM,SEM,UV-vis,etc.)of array materials and the optimization of experimental conditions,the construction of the colorimetric sensor array chip is completed.Then,evaluate the performance of the designed chip through the identification of representative brand baijius and the detection of fake and inferior baijius.The specific conclusions are as follows:(1)According to the physical and chemical properties of baijiu(alcohol,p H,reducibility,etc.),9 dye reagents that respond well to baijiu were screened to construct a3×3 liquid colorimetric sensor array chip to identify representative baijius.The cross-response between baijiu and colorimetric sensor arrays produces different color patterns,and the?RGB of each array point is used to draw specific fingerprint maps and pattern recognition analysis.The results show that each brand of baijiu produces a fingerprint map which is various from that of other baijius and the brand of baijius can be initially identified with the naked eye.In the three-dimensional PCA diagram,different baijius are separated from each other;The classification accuracy of LDA and HCA are both up to100%with a good repeatability In the blind sample detection based on the LDA model,the correct rate of blind sample recognition is 90.6%,illustrating that the colorimetric sensor array chip can identify the baijiu based on the different properties,and can be used as an effective method for rapid differentiation of baijius.(2)Four different kinds of modified Au and Ag nanoparticles(Cit-Au NPs,TA-Ag NPs,Cys-Ag NPs,TA-Au NPs)sensitive to organic acids in baijiu were synthesized.Organic acids can change the surface charge of nanoparticles and cause to aggregate to varying degrees.Thus,the liquid colorimetric sensor array chip constructed by nano-materials is applied for the identification of organic acids and baijius.The results show that fingerprint maps and LDA can distinguish representative organic acids based on their p Ka or molecular structure.Furthermore,the array chip also has a better recognition effect on organic acids with different concentrations or mixtures.When the array chip is utilized to detect baijiu,the fingerprint maps can be used to identify the baijiu with the naked eye.Then,in the pattern recognition analysis,the array chip can accurately identify different baijius with good stability.In the blind sample test,the accuracy rate of blind sample recognition based on the LDA model was 93.75%.In addition,it is worth noting that even if the baijiu sample is diluted by 1%,it can be distinguished from the original baijiu by the array chip,demonstrating the excellent baijiu detection performance of this chip and can be used for baijiu quality control.(3)Three kinds of nanomaterials:Au nanoparticles(Au NPs),molybdenum disulfide(Mo S₂)nanoflowers,and 2-methylimidazole zinc salt(ZIF-8),were synthesized successfully and combined with the selected dyes.Then,a 25-unit paper-based colorimetric sensor array chip was constructed to identify a single volatile gas in baijiu and baijiu through cross-response.The outcomes show that the array chip can discriminate 8 representative gas volatile substances in baijiu,and LDA confirms that the array also has ability to identify gas mixtures.For the detection of baijiu,fingerprint maps and pattern recognition analysis can accurately distinguish 16 kinds of representative baijius,and exhibit good repeatability and stability in the detection process.Furthermore,the correct recognition rate of the array chip for blind samples is90.6%.Additionally,the blended fake baijiu can also be distinguished from the real baijiu by fingerprint maps and HCA,indicating that the paper-based colorimetric sensor array chip has a strong practical application value in baijiu detection.