Abstract
The conscious of environmental protection is beginning to wake up. The harmful materials are also starting to be forbidden and diminished. Besides, the complicated matrix of environmental samples and trace amount of analyte make up placing importance on the preconcentration technique. In recent years, dispersed liquid-liquid microextraction (DLLME) has been developed particularly rapid, which experimental process is simple, fast, and low cost … and so on. But it used a lot of organic matter as dispersed solvent which can cause environmental burden and increase the extraction solvent with the analyte dissolved in the water. In this studty, we replace large amounts of organic to water containing very low concentration (1 mgL－1) of surfactant as the dispersed solvent which assisted a small amount of extraction solvent (10~12 μL) to emulsion. We used microinjection needle back and forth four times to mix within 10 seconds and then injected into water samples for extraction. We select low toxic non-chloro extraction solvent by using the improved solvent collection system (ISCI) which developed in our laboratory. And than use gas chromatography with electron capture detector (GC-ECD) to analye five common organochlorine pesticides like heptachlor, α-Endosulfan, p,p'-DDE, o,p'-DDD, Endrin in water sample. Developed a pre-treatment combined with enrichment extraction method which is sensitive, simple, fast and more environmentally friendly and used to compare with another methods. In the first study, we used dodecyl acetate (12 μL) as the extraction solvent. Under optimized conditions, the results indicate that linear range of the method was 5~5000 ngL－1 with the R2 ≧0.9963, the method detection limit from 1 to 5 ngL－1, the quantitative detection limit from 3 to 17 ngL－1. The precision for inter-day was within 6.1~12.9 %. The precision for intra-day was within 9.7~14.4 %, the enrichment factor between 1901 and 3530. In lake water, the absolute recoveries were within 20.8~43.5 %, the relative recoveries were within 83.2~109.8 %, the precision from 7.1 % to 14.8 %. In sea water, the absolute recoveries were within 19.9~49.2 %, the relative recoveries were within 85.4~115.9%, the precision from 3.0 % to 13.6 %. In the second study, we used 2-dodecanol (10 μL) as the extraction solvent. Under optimized conditions, the results indicate that linear range of the method was 1~10000 ngL－1 with the R2 ≧0.9970, the method detection limit from 0.5 to 2 ngL－1, the quantitative detection limit from 1.7 to 6.7 ngL－1. The precision for inter-day was within 4.0~5.1 %. The precision for intra-day was within 5.0~10.3 %, the enrichment factor between 1881 and 3108. In sea water, the absolute recoveries were within 25.7~42.2 %, the relative recoveries were within 96.3~111.2 %, the precision from 1.2 % to 8.5 %. In stream water, the absolute recoveries were within 22.4~41.9 %, the relative recoveries were within 90.7 ~107.9 %, the precision from 1.4 % to 6.4 %. We developed a simple, rapid method of extraction. We used very small amount of volume, cheap, low toxicity, halogen-free extraction solvent and used water which was environmentally friendly, very low amount of volume, containing very low concentrations of surfactants as a dispersed solvent. It can be emulsified completely in a very short period of time. The method has very low detection limit and a high enrichment factor. The application of this experiment on the lake, sea and stream water with good recovery and precision. This method provided very convenient and high availability pre-treatment methods in environmental samples.