Otimização de método analítico para determinação do inseticida bifentrina em amostras de alimentos industrializados

Abstract

The bifenthrin pyrethroid insecticide has been widely used for pest control, not only in crops, but also in industrial settings and commercial establishments. If integrated pest control is not performed properly, there is a risk of contamination of shelf products. The objective of this work was to develop and compare two analytical methods based on gas chromatography with electron capture detection (GC/ECD) and high performance liquid chromatography coupled todiode array detector (HPLC/DAD), for determination of bifenthrin insecticide in samples of industrialized foods with varied compositions and characteristics. After optimization of the separation by HPLC/DAD and CG/ECD, representative samples of the whole sample (high moisture content/low lipid content and low moisture content/high lipid content) were submitted to numerous tests in order to optimize the analytical conditions. Thus, the conditions for the microwave extraction and clean up through using solid phase extraction (EFS) in activated Florisil column were optimized. Then, the previously optimized methods were evaluated by comparing the following figures of merit: linearity, sensitivity, accuracy and precision. For both methods, adequate selectivity and high accuracy were observed, with recoveries ranging from 86.4 to 101.1% and from 99.5 to 90% for CLAE/DAD and CG/ECD, respectively. Coefficients of variation <5% evidenced high precision for both methods. Regarding sensitivity, however, the method based on CG/ECDwas more efficient, with LD and LQ values of 2.1 ng/L and 7.1 ng/L, respectively, whereas the method based on HPLC/DAD presented values of LD and LQ of 7.4 ng/L and 24.5 ng/L, respectively. Thus, the method based on the CG/ECD technique was selected to analyze 22 samples of supposedly contaminated foodstuffs as well as some of the packages. The results evidenced the absence of contamination in the samples, being the analytical methodology considered adequate for routine analysis of complex samples, since it presented high efficiency, quickness and relatively low cost.