Simultaneous multi-residue pesticide analysis in southern Brazilian soil based on chemometric tools and QuEChERS-LC-DAD/FLD method.

Abstract

A simple and straightforward QuEChERS extraction method was proposed for the simultaneous determination of atrazine (ATZ), desethylatrazine (DEA), desisopropylatrazine (DIA), carbaryl (CBL), carbendazim (CBD), and diuron (DIU) in soil with high agricultural activity from southeastern Brazil, using high-performance liquid chromatography-diode-array detection/fluorescence detection. Screening studies carried out by 24 factorial design indicate better recoveries when less sample (1.0g) and the volume of solvent (2.0mL of ACN) were applied, compared to the original QuEChERS method. Furthermore, interactions between factors were not negligible in the experimental set, except for ATZ and DIU, in which only water volume influenced their recovery. The influence of the type (primary secondary amine (PSA), C18, and Florisil) and the sorbent amount ratio to the compounds' concentration were also considered. PSA (25mg) was selected as the best sorbent without losing analytical response. The limits of quantification (LOQ) were estimated to be 5.0 to 15µgkg-1 in the soil matrix. Analytical performances were consistent with linearity (R2 ≥ 0.998), recovery from 74.7 to 108%, and relative standard deviations (RSD) between 2.6 and 20.2%. Robustness was assessed by fractional factorial Plackett-Burman design. The method is recommended for chemicals that are soluble in water, and it was successfully applied in the analysis of real soil samples containing the analytes in the range of μg kg-1, proving to be suitable for the study of soils strongly impacted by agricultural activity.