Abstract
The purpose of this work was to develop a highly selective, sensitive, and reliable method for multi-residual analysis. A three-dimensional microporous reduced graphene oxide/polypyrrole nanotube/magnetite hydrogel (3D-rGOPFH) composite was synthesized and utilized as a magnetic solid-phase extraction (MSPE) sorbent to preconcentrate thirteen insecticides, including five organophosphorus (isocarbophos, quinalphos, phorate, chlorpyrifos, and phosalone), two carbamates (pirimor and carbaryl), two triazoles (myclobutanil and diniconazole), two pyrethroids (lambda-cyhalothrin and bifenthrin), and two organochlorines (2, 4′-DDT and mirex), from vegetables, followed by gas chromatography-tandem mass spectrometry. This method exhibited several major advantages, including simultaneous enrichment of different types of insecticides, no matrix effect, high sensitivity, and ease of operation. This is ascribed to the beneficial effects of 3D-rGOPFH, including the large specific surface (237 m2 g−1), multiple adsorption interactions (hydrogen bonding, electrostatic, π–π stacking and hydrophobic interaction force), appropriate pore size distribution (1–10 nm), and the good paramagnetic property. Under the optimal conditions, the analytical figures of merit were obtained as: linear dynamic range of 0.1–100 ng g−1 with determination coefficients of 0.9975–0.9998; limit of detections of 0.006–0.03 ng g−1; and the intra-day and inter-day relative standard deviations were 2.8–7.1% and 3.5–8.8%, respectively. Recoveries were within the range of 79.2 to 109.4% for tomato, cucumber, and pakchoi samples at the fortification levels of 5, 25, and 50 ng g−1. This effective and robust method can be applied for determining multi-classes of insecticide residues in vegetables.
Highlights
Insecticides (e.g., organophosphorus pesticides (OPPs), organochlorine pesticides (OCPs), pyrethroids, and carbamates) are widely used for pest control in agriculture and residential places.many insecticides are carcinogenic, teratogenic, and mutagenic to human cells
After being self-assembled with graphene oxide (GO) and Fe3 O4 nanoparticles, the well-defined black hydrogel in a cylindrical shape floated on the top of the system
Very clean spectra with a low baseline were obtained in the total ion chromatograms of spiked or un-spiked blank vegetables (Figure 4). These results demonstrated that 3D-rGOPFH could be an efficient magnetic solid-phase extraction (MSPE) extraction sorbent for reducing the matrix interferences
Summary
Insecticides (e.g., organophosphorus pesticides (OPPs), organochlorine pesticides (OCPs), pyrethroids, and carbamates) are widely used for pest control in agriculture and residential places. Many insecticides are carcinogenic, teratogenic, and mutagenic to human cells. Long-term accumulation in vivo of insecticides can seriously harm the nervous, genital, and immune systems of the human body [1]. Maximum residue limits (MRLs) were set strictly by many organizations toward insecticides. The European Union (EU) has set the MRLs at 0.01–0.3 μg g−1 for insecticides, such as OPPs and pyrethroids, in vegetables [2]. Developing an effective analytical method for trace-level determination of insecticide residues is indispensable and highly necessary
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