Fluorescence detection of paclobutrazol pesticide residues in apple juice

The fluorescence spectrum of paclobutrazol solutions and the apple juice - paclobutrazol mixed solutions are detected, which have a distinct characteristic peak at 341 nm. Regression analysis is performed on the fluorescence spectrum and its derivative spectrum of paclobutrazol solutions and the apple juice - paclobutrazol mixed solutions. The corresponding prediction model functions between the concentration and fluorescence intensity of two methods are obtained respectively. In the original spectrum mode of paclobutrazol solutions, the correlation coefficient is 0.9999 at 341 nm, the recovery rate is 99 %–103 %, the average recovery rate is 100.45 %, and the relative standard deviation (RSD) is 1.4506 %. In the derivative spectrum mode of paclobutrazol solutions, the correlation coefficient is 0.9998 at 321 nm, the recovery rate is 98 %–103 %, the average recovery rate is 100.3 %, and the relative standard deviation (RSD) is 1.7095 %. In the original spectrum mode of the apple juice - paclobutrazol mixed solutions, the correlation coefficient is 0.9999 at 341 nm, the recovery rate is 98 %–100 %, the average recovery rate is 99.625 %, and the relative standard deviation (RSD) is 0.5208 %. In the derivative spectrum mode of the apple juice - paclobutrazol mixed solutions, the correlation coefficient of paclobutrazol is 0.9992 at 321 nm, the recovery rate is 94 %–99 %, the average recovery rate is 97.000 %, and the relative standard deviation (RSD) is 2.2031 %. The experiment results show that the derivative spectrum could enhance the detailed characteristics of spectral scanning due to the advantages of narrow bands, high sensitivity and large amount of information. However, the derivative spectrum method has no significant advantage over the original fluorescence spectrum in the quantitative paclobutrazol prediction. Therefore, the modeling analysis could be performed on the original fluorescence spectrum at 341 nm directly. The research results in this paper provide experimental reference for the quantitative detection of pesticide residues.