Development of dispersive solid-phase microextraction coupled with high-pressure liquid chromatography for the preconcentration and determination of the selected neonicotinoid insecticides
Ngwako Joseas Waleng, Shirley Kholofelo Selahle, Anele Mpupa, Philiswa N. Nomngongo
Abstract
Abstract Neonicotinoid insecticides have raised a lot of societal concerns due to their environmental ubiquity and unique mode of action. Therefore, it is of great research interest to monitor their occurrence in the environmental waters. However, these compounds exist at low concentrations that is below instrument detection limits. This study reports the applicability of magnetic poly (3 aminobenzoic acid)-based activated carbon (Fe 3 O 4 @PABA/AC) composite as an adsorbent in dispersive magnetic solid-phase microextraction ( d -MSPME) of neonicotinoid insecticides from wastewater and river water samples. The as-synthesized adsorbent was characterized and confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller and X-ray diffraction spectroscopy. The analytes of interest were detected and quantified by high-performance liquid chromatography coupled with diode array detector (HPLC–DAD). The parameters affecting the extraction and preconcentration processes, such as pH, extraction time, mass of adsorbent, desorption time and eluent volume, were optimized using fractional factorial design and central composite design. Under optimum conditions, the limits of detection and quantification were in the ranges of 0.41–0.82 µg L −1 and 1.4–2.7 µg L −1 , respectively. The linearity ranged from 1.4–700 µg L −1 with correlation of determination ( R 2 ) values varied between 0.9933 and 0.9987. The intra-day and inter-day precisions were 0.35–0.75% and 1.7–5.5%, respectively. The spike recovery experiments were conducted to evaluate the accuracy of the d -MSPME analytical method in real samples, and the percentage recoveries ranged from 86.7 to 99.2%. Therefore, this method shows great potential applicability in preconcentrating the pollutants from the environment.