Desenvolvimento de metodologia para a determinação de fungicidas da classe das estrobilurinas usando cromatografia líquida de alta eficiência com detecção simultânea ultravioleta e eletroquímica

Abstract

Synthetic strobilurins fungicides are produced and marketed all over the world, being among the best selling ones due to their efficiency against several fungi. For public health security reasons, ANVISA (National Health Surveillance Agency) classifies synthetic strobilurins as highly or moderately toxic. Therefore, legislation has been increasingly stricter regarding pesticides in general, including strobilurins. This study aimed to develop an analytical method for the determination of seven strobilurins using HPLC with simultaneous ultraviolet (UV) and electrochemical/amperometric (DE) detections, in addition to its application for the analysis of bean samples. The electrochemical detector was coupled to the HPLC in a homemade way. The separation method for the seven strobilurins by HPLC employing C18 reversed phase column was optimized from the study of such parameters as the composition of the mobile phase and the elution mode, evaluating, among others, peak resolution and symmetry. For UV detection the wavelength was suitably selected, while for the amperometric detection the potential electrolysis was chosen, using a boron-doped diamond electrode (DDB) as the working electrode. UV detection was performed at 200 nm and amperometric detection at 1.9 V. An extraction method was optimized for the strobilurins, which was adequate, selective and efficient in removing interfering substances. In the accuracy evaluation of the method, the recovery values obtained for strobilurins were between 61.6% and 98.8%, with standard deviations lower than 10.0%. The detection limits of the method were 0.02 mg kg -1 for all the strobilurins, and the quantification limits ranged from 0.06 to 0.07 mg kg-1, obtained by UV and DE detection. UV and DE detection methods were statistically compared, which showed no significant differences between the results reported by them at a 95% confidence level. Seven samples of bean of different types and origins were analyzed, but none of the strobilurins studied in this work were detected.