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Application of hollow-fiber-assisted liquid-phase microextraction to identify avermectins in stream water using MS/MS.

In this study, a hollow-fiber-assisted liquid-phase microextraction (HF-LPME) technique coupled with LC-MS/MS is described to detect avermectins (abamectin, ivermectin, moxidectin, and doramectin) in stream water. An Accurel polypropylene membrane was used as the hollow fiber, and dihexyl ether was used as the extraction solvent. The optimal extraction conditions for HF-LPME were 4 cm fiber length, 45 min extraction time, 200 rpm, and 1 min desorption time with methanol as the desorption solvent. The linear range was 0.15-100 ng/mL (r(2) = 0.994-0.998), and the LOD and LOQ were 0.15 and 0.5 ng/mL, respectively. Recovery rates were determined at 1, 5, and 10 ng/mL, and the results were in the range of 80.1 to 93.7%. The intraday and interday repeatability ranged from 2.8 to 8.0% and from 6.1 to 13.3%, respectively. The HF-LPME method developed was applied to detect avermectins in stream water samples collected from 14 different sites near livestock farms located in Honam area, Republic of Korea; however, none of the samples contained avermectin residues. HF-LPME combined with a LC-MS/MS method was successfully applied for an environmentally friendly identification of avermectins in water samples. HF-LPME represents an attractive approach for conventional liquid-liquid extraction.