Comparative Study Between VWD and FLD Detector in HPLC System for Azoxystrobin Quantification in Water

In this study, the efficiency of two detectors—variable wavelength detector (VWD) and fluorescence detector (FLD)—in a liquid chromatograph to quantify azoxystrobin in water was compared. For this, a method was developed in a HPLC-VWD-FLD system using extraction by modified QuEChERS. The detection of azoxystrobin by fluorescence was possible using only a solvent effect, considering that azoxystrobin does not naturally fluoresce. Analytical curves were constructed using matrix-matched calibration, where a low matrix effect was verified in both detectors. In the linearity analysis of the analytical curves, the values of coefficient of determination ​​found for the detectors were 0.9989 and 0.9983 for VWD and FLD, respectively. The relative standard error for the VWD detector was 6.96%, while for the fluorescence detector, it was 5.49%. The limit of detection (LOD) and the limit of quantification (LOQ) were, respectively, 0.33 and 0.68 mg L −1 (VWD) and 0.18 and 0.37 mg L −1 (FLD). The QuEChERS method, originally developed for the extraction of pesticides in food, was adapted for the extraction of azoxystrobin in water, demonstrating efficiency in the process, with precision values ​​lower than 20% and accuracy between 83.58 and 112.88%, within the criteria established by MAPA and Document Nº SANTE/11312/2021. Therefore, it is concluded that both detectors are suitable for the analysis of azoxystrobin in water; however, there is a greater sensitivity for the fluorescence detector, since lower detection and quantification limit values ​​were observed, in addition to a lower standard relative error (RSE).