Development of analytical methods for monitoring the degradation of pesticides in biobeds

MAGNI, FLORENCIA VALENTINA; CLEBOT, ALDANA; LAMMERTYN, SOFÌA; DEMONTE, LUISINA; MICHLIG, MELINA; ZALAZAR, CRISTINA; REPETTI, MARIA ROSA

Ciudad de Panamá

Workshop; 9TH Latin American Pesticide Residue Workshop (LAPRW); 2023

Ministerio de Desarrollo Agropecuario de Panamá (MIDA)

Initially, biological beds or biobeds were designed for the treatment of wastewaters from the washing of fumigation equipments and the accidental spillage of agrochemicals, while currently its use was extended to other types of effluents that might be contaminated with phytosanitary products.For this work, beds composed of a biomixture of soil, wheat stubble and humidified materials were prepared to treat wastewater polluted with agrochemicals. The study was carried out monitoring the degradation of 5 compounds in each of two stages over a period of 120 days. For the analytical determination of the first group of pesticides (atrazine, clethodim, haloxyfop, promethrin and dicamba) the samples were extracted three times (twice with methanol and one with acetonitrile and MgSO4 Anh.). The second group of pesticides (acetochlor, cypermethrin, dimethoate and imidacloprid) were extracted using the QuEChERS method with PSA and C18 in the cleaning stage. Finally, for 2.4-D was extracted using a double extraction with dichloromethane. The instrumental analysis was done by UHPLC-MS/MS and GC-MS/MS. In all cases, the methods were validated according to the requirements of the SANTE Guideline (1), evaluating linearity, limits of quantification, accuracy and precision, and matrix effect. The extraction recoveries of all compounds were between 70-120% using matrix calibrations curves, relative standard deviations were below 20%, and limits of quantification and detection were 10 and 5 µg/kg for all pesticides, respectively.The results from the degradation assay showed that during the period of 120 days the initial concentration of the 10 studied pesticides in the biobeds was reduced by more than 95%, proving that this type of decontamination systems are simple and low-cost alternatives for the treatment of agricultural effluents.