Simultaneous determination of deltamethrin and 4 other pyrethroids residues in infusion tea: Preliminary study

Abstract

Deltamethrin and other pyrethroids, which were thought to be relatively safe pesticides, recently are gaining concerns due to their toxicity. Residues of deltamethrin and other pyrethroids incur in tea-related products, such as tea-based functional beverage, due to the pesticide application at tea plantations, thus their concentrations need to be monitored. This preliminary study was aimed to develop a method for simultaneous analysis of deltamethrin and 4 other pyrethroids in infusion tea implementing low volume liquid-liquid extraction to extract the target compounds, followed by quantification by gas chromatography coupled with micro electron capture detector (GC-μECD). The GC-μECD was firstly optimized for the quantification of deltamethrin and 4 other pyrethroids. The optimization of the instrument was able to detect the pyrethroids at 0.1 μg/L with good repeatability showed by %RSD of 1.97­10.21%, which was very much lower compared to the AOAC guideline at 1 ppb level (30%). Simultaneous analysis of mix standard solutions at concentration ranges of 1 to 10 μg/L showed very good linearity (r>0.997). In addition, the low volume liquid-liquid extraction using n-hexane was able to detect the target pyrethroids from the spike experiment of infusion tea samples as low as 0.67 μg/L.