New Analytical Methods For Food And Drug Adulteration And Pesticide Residue Detection Based On Multivariate Spectroscopy And Nanometer Effect Colorimetric Sensing

Food and drug are vital construction content to accelerate the improvement of people’s livelihood.Food and drug safety is an essential part of the national security strategy,so effective food,and drug quality analysis and rapid detection methods are crucial to maintaining national security and protecting people’s health.In recent years,unscrupulous traders use adulteration to earn a price difference for profiteering,farmers to prevent pests from improving crop yields exceed the standard,or irregular use of pesticides,resulting in the market for food and drug adulteration and pesticide residues exceeding the standard and other severe food and drug safety issues.The development of a series of susceptible,specific,convenient,and rapid methods for detecting adulteration and pesticide residues is of great practical significance and potential.Therefore,this paper summarizes and analyzes the current situation and development trend of domestic and foreign research related to the quality and safety analysis of food and drugs in recent years,and develops a series of new multivariate spectroscopic and colorimetric sensing methods and applies them to the identification of food and drug adulteration and pesticide residue detection system.The main research contents are as follows:（1）This paper firstly introduces the cutting-edge analytical methods and urgent problems of food and medicine quality and safety at home and abroad,then summarizes the current research status of multivariate spectroscopy and colorimetric sensing methods in food and medicine quality analysis and safety detection,and finally presents the research significance and innovation points of this work.（2）Aiming at the problems that adulteration of food and medicine on the market is difficult to identify by the naked eye and that large instrumental analysis methods such as chromatography are time-consuming,consumable,and specialized,a new method based on near/mid-infrared spectroscopy combined with chemometric models such as partial least squares discrimination analysis（PLS-DA）and proximity algorithm（k NN,K-Nearest Neighbor）has developed for the authentication of saffron（foreign Iran）and three common adulterants such as Carthamus tinctorius L.,lotus stamens,and corn stigmas.Firstly,the near/mid-infrared spectroscopy data of the original saffron and the adulterated saffron with different proportions were collected.Then,the near/mid-infrared spectroscopy of the pure saffron and the adulterated saffron,corn whiskers,and lotus whiskers were modeled and analyzed using PLS-DA and k NN models.In the NIR spectral analysis,its classification results showed that the discriminative accuracies of the training and prediction sets of the PLS-DA model were 100%and 98.7%,respectively,while the accuracy of both the training and prediction sets in the k NN model reached 100%.It is noteworthy that the accurate identification rates of both training and prediction sets of PLS-DA and k NN models based on mid-infrared spectra reached 100%under the same chemometric pattern recognition.Compared with the near-infrared spectroscopy detection method,this method increases the extraction amount of characteristic spectral information of different functional groups in food and drug samples,achieves a better recognition effect.The partial least squares regression（PLSR）model was further used to predict the adulteration levels of the three adulterants,and satisfactory results were obtained.In conclusion,near/mid-infrared spectroscopic techniques combined with chemometric methods have good applications in the identification of saffron adulteration.Different infrared spectroscopy techniques combined with the preferred chemometric methods can achieve rapid,efficient and nondestructive adulteration identification for more food and drug samples.（3）To address the problems of peak overlap,the high similarity of spectrograms,and difficulty in resolving complex systems in near/mid-infrared spectra,this chapter proposes nano-effect excited emission matrix fluorescence combined with chemical pattern recognition for rapid authenticity identification saffron.First,hydrophilic hydrazine-naphthalimide functionalized chitosan（HN-chitosan）polymer probes with multiple hydrazine-naphthalimide recognition sites were synthesized.Based on the specific reaction between hydroxyl functional groups in saffron and amino functional groups in chitosan probes,the differences in fluorescence spectra signals between saffron and adulterants were amplified.The excitation-emission matrix fluorescence spectra were resolved by classical chemometrics using using Principal component analy-linear discriminant analysis（PCA-LDA）,Random forest（RF）,PLS-DA,and k NN models,and the results showed that the four models achieve satisfactory results in both training and prediction sets,with PCA-LDA and PLS-DA models achieving 100%accuracy in both training and prediction sets.The adulteration level of adulterated saffron was predicted using the PLSR regression model,and the R² of the PLR model was 0.9982,1.0000,and 0.9975 in saffron,lotus beard,and corn beard,respectively,indicating that the model is reliable.In this system,the synthesized nanomaterials precisely identified the color-related indicator component saffron glucoside I in saffron,improving its selectivity while achieving effective identification against the staining phenomenon in saffron adulteration.This method enhances the specificity of the food and drug adulteration and provides a new idea for the quality research of food and drug.（4）Compared with food and drug adulteration,the pesticide residue phenomenon is more prominent in food and drug safety problems,causing a more serious threat to people’s lives and health,and there is an urgent need to develop simple,rapid and efficient pesticide residue detection methods.The fluorescence spectroscopy method mentioned in the previous chapter has the characteristics of high sensitivity and simple operation,and a variety of fluorescence sensing can be constructed by designing and synthesizing different fluorescent probes,which can be used not only for the identification of food and drug adulteration,but also has great potential for application in the detection of pesticide residues.So this chapter is therefore based on the specific reaction between systemic pesticide and nanosized metalloporphyrins（DTAB-Cu TPy P）.,taking monosultap as an example.Monosultap combined with DTAB-Cu TPy P through electrostatic interactions,competitively robbing DTAB-Cu TPy P that reacts with BSA-Cu NCs,resulting in the inability of DTAB-Cu TPy P to induce BSA-Cu NCs aggregation,and the fluorescence of BSA-Cu NCs increased with increasing concentration of added monosultap.By fitting the linear equation of the change in fluorescence intensity values of BSA-Cu NCs at400 nm with the concentration of monosultap,there was a good linear relationship between them in the linear range of 0.33×10^-2-3.33×10^-2mg/kg.The detection limit was 0.098 mg/kg,which was much lower than the max residue level of 0.2 mg/kg.The method was successfully applied to food and medicine samples such as cabbage,apple and chrysanthemum.The spiked recoveries of the four different samples ranged from 91.14%to106.75%,indicating that the method has good applicability in food and medicine samples and has the potential to be applied to more complex food and medicine samples for the determination of systemic pesticides by synthesizing different functional fluorescent probes.（5）In response to the previous chapter fluorescence intensity changes are difficult to distinguish with the naked eye,in order to meet the demand for simple,portable,instrument-free field testing of pesticide residues and to further improve visualization of systemic pesticide detection by the naked eye,in this chapter,a multicolor colorimetric sensor was constructed for the quantitative detection of carbaryl in food and medicine based on the specific reaction between systemic pesticide and nanosized metalloporphyrin（Zn TPy P-DTAB）in combination with the chromophoric nanomaterial biconical nanogold（Au NBPs）,and the semi-quantitative detection of carbaryl was achieved by combining digital image colorimetric method based on visualization with the naked eye.First,the peroxidase-like activity of Zn TPy P-DTAB catalyzed the decomposition of H₂O₂ into hydroxyl radicals and etched Au NBPs.With the morphological changes of Au NBPs,the positions of their LSPR peaks also changed continuously.With the help of a UV-Vis spectrophotometer,a good linear relationship was detected between the concentration of carbaryl and the degree of blue shift of Au NBPs LSPR peaks in the range of 0.8-8.0mg/kg.However,its detection limit was 0.26 mg/kg,much lower than its permissible maximum residue limit（5 mg/kg）.As the concentration of carbaryl increased from 0.8 mg/kg to 8.0 mg/kg,the color of the solution changed in the order from orange-pink-purple（below 5 mg/kg）to blue-green（above 5 mg/kg）.The color changes observed by the naked eye were transformed into an RGB values for subsequent analysis.The constructed partial least squares regression models all had R² greater than0.999 and RMSEC as low as 0.0031,and their detection limits were 4.06mg/kg.This indicated that the quantitative model could be used to effectively quantify carbaryl in food and drugs.The method features visualization of rich color changes with the naked eye and digital images with significant distinctions,which provides a new idea for the visual semi-quantitative detection of pesticide residues in food and drugs.It is expected to be widely used as an in situ instrument-free detection technique for detecting systemic pesticides in various food and medicines.