Ionic liquid-based dispersive liquid-liquid microextraction followed by high-performance liquid chromatography for the determination of organophosphorus pesticides in environmental water samples

• Main Authors: Yi-Chen Ting, 丁宜珍
• Other Authors: Min-Jane Chen
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/37789410055306360483

碩士 === 國立嘉義大學 === 應用化學系研究所 === 98 === Organophosphorous pesticides (OPPs) are widely used for agricultural activities due to their relatively low price and effective control of pests, weeds and diseases. Extensive use of these toxic substances would cause environmental pollution, trace amount of organic phosphorus compounds had been detected in surface water and soil etc. Due to the low concentration of analytes in complex matrices, an appropriate method of sample preparation was needed to solve the problem of poor sensitivity by using high-performance liquid chromatography (HPLC) with UV detection. In this study, imidazolium based room temperature ionic liquids were used as green extraction solvents in dispersive liquid-liquid microextraction (DLLME), and coupled with HPLC-UV detection for the determination of OPPs residues in environmental water samples. Guthion, Diazinon, Phorate and EPN, four typical OPPs, were used as the model analytes in this work. Parameters including types and volume of extraction and disperser solvents, vortical time and centrifugal time, salt addition and extraction temperature were investigated and optimized. Under optimum extraction procedure, 35 μL of 1-hexyl-3-methyl-imidazolium bis(trifluoromethyl-sulfonyl)imide ([C6MIM][NTf2]) was used as extraction solvent, mixed with 0.8 mL methanol (disperser solvent), and quickly injected into an aqueous sample to form a cloudy solution, followed by shock for 20 seconds, centrifugation for 8 minutes. Then, 20 μL of the sediment was withdrew and dissolved in 10 μL of methanol. The extractant was analyzed under optimal HPLC condition (77:23 methanol/H2O, flow rate of 0.5 mL/min) and detected at UV 245 nm. The linearity was observed in the range of 10-20000 ng mL-1 for four analytes. Calibration graphs which were based on peak area versus concentration, and good linearity was exhibited with correlation coefficient (R2) ranged from 0.9996 to 0.9998. The relative standard deviations (RSDs, n=8) of four analytes were 1.4-3.6 %. The limits of detection calculated at a signal-to-noise ratio (S/N) of 3 were in the range of 0.3-2.3 ng mL-1. Finally, this method was applied to the real environmental water samples (tap water, Lan-Tan reservoir source water, water of rice field and corn-washing water), the relative recoveries of spiked water samples were 72.7-117.5 % and 73.4-115.2 %, at two concentration levels of 75 and 200 ng mL-1, respectively.