Application Of Environmentally Friendly Dispersive Liquid-Liquid Microextraction For Analysis Of Trace Metal Element

In order to achieve accurate and reliable results in chemical analysis,it is crucially important to make sample preparation for some complex matrix,low concentration heavy metal elements in the actual sample.Therefore,an efficient,simple,sensitive pretreatment technology has been one of the important research direction for analytical chemistry workers.For the last several years,dispersive liquid-liquid microextraction(DLLME),as a unique method,which integrates sampling,separation and enrichment in a simple step,was developed.It is a new environment friendly sample pretreatment technique which uses only a small amount of organic solvent for enriching analytes from environmental water samples.The green solvents instead of traditional organic solvent,which has disadvanges of strong volatile,high toxic,serious damage to the environment,have been widely used in separation and extraction process.In this paper,on the basis of a large number of previous work,used green solvents instead of organic solvent combing dispersive liquid-liquid microextraction method to extraction and concentration the target analyte in samples.The main research contents are as follows:1.A novel,sensitive approach of magnetic retrieval of ionic liquid dispersive liquid-liquid microextraction(MR-IL-DLLME)technique combined graphite furnace atomic absorption spectrometer(GFAAS)was applied to determine the trace cadmium(Cd)in water samples.The magnetic ferroferric oxide(Fe3O4)nanoparticles were used as the magnetic adsorbent and the ionic liquid([C6MIM][PF6])was chosen as the extraction solvent.Several important factors affecting phase separation,for example dosage of adsorbent,the kind and amount of extraction solvent and dispersive solvent,extraction time,salt effect were optimized in detail.Under the optimum experimental conditions,the enrichment factor was 46,the Linear range was 0.01-0.5 ng/mL,the relative standard deviation was 5.2%and detection limit was 0.012 ng/mL,respectively.Then,the method was successfully applied in environmental water samples,and the relative recovery was 94.1-101.2%.2.A fast,efficient method for the analysis of heavy metal elements was developed using Sodium dodecyl sulfate and cetyl trimethyl ammonium bromide(SDS/CTAB)based DLLME.A variety of factors that affect the extraction effect of SM-DLLME were optimized.Under the optimum experimental conditions,the enrichment factor was 69,the Linear range was 0.01-0.1 ng/mL,the relative standard deviation was 3.6%and detection limit was 0.036 ng/mL,respectively.This procedure was successfully used for analysis of the trace cadmium(Cd)in environmental water samples and the relative recovery was 95.7-99.3%.3.A new,efficient and environmental benign method(CP-DLLME-GFAAS)was established for the determination of nano silver(AgNPs)in water sample.Nonionic surfactant(TX-114)was chosen as the extraction solvent.Several important factors affecting phase separation,for example pH of sample,and volume of TX-114,water bath temperature,salt effect,water bath extraction time were optimized in detail.Under the optimum experimental conditions,the enrichment factor was 76,the Linear range was 0.1-10 ng/mL,the relative standard deviation was 2.2%and detection limit was 0.030 ng/mL,respectively.The method was successfully applied to analysis the trace AgNPs in the environmental water samples and obtained satisfactory results,and the relative recovery was 94.0-104.0%.