| Sample pre-treatments in the analysis play an important role. On the basis of the liquid - liquid extraction, liquid-phase micro-extraction (LPME) technique which is an alternative sample preparation technique has emerged dramatically in the 1990s. The technology overcoming many shortcomings of the traditional extraction uses just a little solvents for extraction and its extraction device is relatively simple, low-cost and easy combination with the gas chromatography, high performance liquid chromatography, capillary electrophoresis which adaptes to the requirements of the modern scientific analysis. The LPME combines sampling, extraction, concentration and sample introduction in a single step and is a simple, cheap, sensitive and environmental friendly sample preparation technique and especially is applicable to determinate the trace and ultra trace pollution in the environment. With hollow fiber membrane protected the liquid phase microextraction not only conquers the disadvantage for the hanging drop in microextraction easily falls off but also has a good sample purification. After 13 years LPME has been widely applied in the environment, food, biology, pharmacy, tobacco and other fields. However, there are less relevant reports about the application of LPME in China. This paper studies the followings:1. The application of hollow fiber liquid-phase microextraction (HF-LPME) combined with gas chromatography-mass spectrometry (GC-MS) for the determination of pyrethroid pesticides in water was studied. The static HF-LPME was selected for present purpose. The experimental parameters that affect the extraction efficiency of static HF-LPME, such as extraction mode, organic solvent selection, solvent volume, extraction time, extraction temperature, stirring rate and salt content were optimized. Under the optimum conditions, the concentration enrichment factors for pyrethroid pesticides were from 63-fold to 292-fold. The calibration curves were linear over a range of 0.3-100μg/L, The limits of detection (LODs, S/N=3:1) were calculated in a range of 0.09-0.41μg/L. The recoveries for spiked water samples ranged from 92.4% to 95.8%. The relative standard deviation (RSD) ranged from 1.9% to 8.6%.2. Application of hollow fiber membrane/liquid-phase microextraction combined with gas chromatography-mass spectrometry on the determination of two fungicides (Vinclozolin, procymidone) in water was studied. The variable experimental conditions for the HF-LPME extraction process were optimized. The ideal experimental conditions were as follows: 2.5μL of toluene as the extraction solvent; 10 ml aqueous sample without NaCl addition was extracted for 15 min; extraction temperature of 25°C; 500 rpm of stirring speed. After extraction, 1.0μL of the organic solvent was then injected into GC–MS for further analysis. Under these conditions, the concentration factors for the two fungicides were 34 and 209. The calibration curve was linear over a range of 0.5–100μg/L. The detection limits(S/N=3) were 0.05μg/L and 0.08μg/L, The recoveries for real water samples were in range of 86.3%-87.1%. Results indicated possibility of applying HF-LPME in analysis of the two fungicides in water attributed to of the convenience, sensitivity low cost of the method.
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