Study On Determination And Speciation Of Trace Arsenic And Mercury And Organophosphorus Pesticides Residues In Environment Samples By Cloud Point Extraction

A new cloud point extraction(CPE)technique was established and used for the determination of trace arsenic(As),mercury(Hg)and organophosphorus pesticides(OPPs)in environmental samples combined with high performance liquid chromatography-hydride generation atomic fluorescence spectrometry(HPLC-HGAFS)and gas chromatography(GC)respectively.1.A method combining CPE with HPLC-HGAFS was proposed for the determination of trace amounts of As(III)and As(V),the two most toxic arsenic species.The pyronin B was selected to complex with the analyst,and Triton X-114 was employed as the extractant.In the experiment,two inorganic arsenic first complexed with pyronin B to form the hydrophobic complex,which can be extracted by Triton X-114.The obtained enriched phase was diluted with acid dilution,the complex bond was broken,and inorganic arsenic was re-existing in the free form,whichsolves the problem that the hydrophobic complex cannot be detected smoothly.The experiment focused on the selection and optimization of diluents,buffer solution,surfactant,complexing agent,inorganic salt selection and dosage.Under the optimal conditions,As(III)in the range of0.3-10.0?g/L and As(V)in the range of 0.6-20.0?g/L showed good linearity(r ? 0.9995),and the detection limit(LOD,S/N=3)was0.038?g/L and 0.075?g/L,respectively.The deviations(RSD)were4.77% and 4.24%,the enrichment multiples were 6.54 and 8.36,and the recoveries of the actual environmental samples were 95.8%-102%.2.A novel cloud point extraction technique was established and used for the determination of trace Hg species in water samples combined with HPLC-HGAFS.Under ultrasound assisted,DDTC was used as the complexing agent for Hg(II)and MeHg,and the hydrophobic complex extracted by Triton X-114,a dual-cloud point extraction technique was then introduced.The enriched phase obtained in one cloud point extraction process was diluted with an aqueous solution containing L-cysteine to carry out secondary cloud point extraction,and Hg formed a hydrophilic complex with L-cysteine into the aqueous phase.The aqueous phase was detected as an on-machine solution and most of the surfactant was removed.Finally,under the optimized experimental conditions,Hg(II)and MeHg have good linearity(r?0.9993)in the range of 0.10-5.0?g/L,and the enrichment multiples are 15.7 and 6.35.The sensitivity of themethod is high(LOD is Hg(II)0.004?g/L and MeHg 0.016?g/L),and the precision is good(RSD?3.15%,n=6).The method can be well applied to the detection and analysis of two mercury forms in environmental water samples with good recoveries between 92.8-110%.3.A back extraction-assisted CPE-GC method for the determination of six organophosphorus pesticides was established.The hydrophilic polyethylene glycol 6000 was used as the extractant.After the cloud point extraction,the back extraction assist was introduced,and a small amount of low-toxic organic solvent was added to the enriched phase.With the aid of ultrasound,the mutually incompatible enriched phase was in full contact with the organic phase,and the analyte entered the organic phase from the enriched phase,and the organic phase was introduced to the gas chromatograph for detection,which solves the problem that the surfactant cannot enter the gas phase detection because of its high cloud point temperature and high viscosity.The organic solvent selects a mixture of ethyl acetate and n-hexane to enable the extraction of different polar analytes.The polyethylene glycol 6000 used in the experiment reduces the cloud point temperature by adding an inorganic salt,so that it can reduce the cloud point temperature,so that it can make the cloud point phenomenon at normal temperature,saving the steps of water bath and ice bath.The method was successfully combined with gas chromatography-flame photometric detector to obtain good analyticalcharacteristics.Six organophosphorus pesticides showed good linearity(r? 0.9958)in the range of 2.5-8000?g/L,LOD was in the range of0.8-5.0?g/mL,and the RSD is ?5.18%.The method was applied to the analysis of 6 kinds of OPPs in environmental water samples and soils,and the recoveries of the spiked samples were 95.2-106%,which showed satisfactory results.