Xiang Li,Chang-Ling Sun,Yu Xu,Shi-Hui Shan,Han Zheng,Xiao-Lu Guo,Jiang-Ning Hu
A novel method for benzo(α)pyrene (Bαp) enrichment from an oil matrix was developed by using magnetic nanoparticles (Fe 3 O 4 @dopamine/graphene oxide, Fe 3 O 4 @DA/GO) as extraction absorbents, and the chemical properties of the synthesized nanoparticles were characterized. Various parameters were investigated to optimize the extraction of Bαp from oils. Under optimal conditions (pH, 4; extraction time, 0.5 min; elution solvent, 1 mL; absorbent weight, 20 mg; elution time, 0.5 min), these nanoparticles showed excellent abilities to enrich Bαp from the saponified oil solution and were easily separated by a magnet. High-performance liquid chromatography plus fluorescence detection (HPLC-FLD) was then applied to determine the Bαp content with excellent linearity (R 2 = 0.999). The detection limit was 0.13 µg/kg, while the limit of quantification was 0.42 µg/kg. The spiked recoveries of Bαp in oils ranged from 73.5% to 121%. Compared with previous reports, the proposed method displayed many advantages, including a high efficiency of oil matrix removal, short extraction time, and convenient extraction procedure.
Magnetic metal-organic frameworks (MOFs, [MIL-101]) were prepared and used as magnetic solid-phase extraction (MSPE) adsorbents for preconcentration of four kinds of pyrazole/pyrrole pesticides (flusilazole, fipronil , chlorfenapyr , and fenpyroximate) in environmental water samples, followed by high-performance liquid chromatography-diode-array detector (HPLC-DAD) determination. Several variables affecting MSPE efficiency were systematically investigated, including amount of MIL-101, extraction time, sample pH, salt concentration, type of desorption solvent and desorption number of times. Under optimized conditions, excellent linearity was achieved in the range of 5.0–200.0 μg/L for flusilazole and fipronil, and 2.0–200.0 μg/L for chlorfenapyr and fenpyroximate, with correlation coefficients r >0.9911. Limits of detection and quantification were 0.3–1.5 μg/L and 1.0–5.0 μg/L, respectively. The intra-day and inter-day precision (relative standard deviation, n =6, %) at three spiked levels were 1.1–5.4% and 3.9–7.8% in terms of peak area, respectively. The method recoveries at three fortified concentration levels ranged from 81.8% to 107.5% for reservoir water samples, 81.0–99.5% for river water samples, and 80.2–106.5% for seawater samples. The developed MOFs based MSPE coupled with HPLC method proved to be a convenient, rapid and eco-friendly alternative to the sensitive determination of pyrazole/pyrrole pesticides with high repeatability and excellent practical applicability.
We report on a method for the extraction of organophosphorus pesticides (OPPs) from water samples using mixed hemimicelles and magnetic titanium dioxide nanoparticles (Fe 3 O 4 @TiO 2 ) modified by cetyltrimethylammonium. Fe 3 O 4 @TiO 2 nanoparticles were synthesized by a hydrothermal process and then characterized by scanning electron microscopy and Fourier transform IR spectrometry. The effects of the quantity of surfactant, extraction time, desorption solvent, pH value, extraction volume and reuse of the sorbent were optimized with respect to the extraction of OPPs including chlorpyrifos, dimethoate, and trichlorfon. The extraction method was applied to analyze OPPs in environmental water using HPLC along with UV detection. The method has a wide linear range (100–15,000 ng L −1 ), good linearity ( r > 0.999), and low detection limits (26–30 ng L −1 ). The enrichment factor is ~1,000. The recoveries (at spiked levels of 100, 1,000 and 10,000 ng L −1 ) are in the range of 88.5–96.7 %, and the relative standard deviations range from 2.4 % to 8.7 %.
Schematic illustration of the preparation of CTAB coated Fe 3 O 4 @TiO 2 and its application as SPE sorbent for enriching OPPs
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