The Analytical Technique And Its Application Of Pyrethroid And Polycyclic Aromatic Hydrocarbonsin Environmental Matrices

Polycyclic aromatic hydrocarbons (PAHs) are widespread in the atmosphere, water, soil, plants as well as in animals and their products. Some of PAHs have high persistence in the environment, carcinogenic and mutagenic properties, low biodegradability, high lipophility and can migrate through the food chain, thus making serious health risk to all living organisms. Due to their hazardous characteristics and ubiquity, 16 PAHs have been included in European Union (EU) and Environmental Protection Agency (EPA) priority pollutant lists; Synthetic pyrethroid (PYR) pesticides constitute another group of insecticides in addition to organochorine, organophosphorus and carbonates. PYR pesticides have greater photostability, enhanced insecticidal activity, and relatively low toxicity as compared with organochlorine and organophosphorus insecticides. Furthermore, they are very lipophilic compounds with high octanol-water partition coefficients (log KO/W>5). Their neurotoxic properties result from interaction both in insects and mammals, which provokes a repetitive nerve action associated with hyperactivity, tremor, ataxia, convulsions, and possible paralysis. In order to investigate their ecological risk, a simple, economic and rapid method is required for the monitoring of PAHs and PYR compounds in environmental matrices.Liquid-phase microextraction (LPME) is based on liquid-liquid extraction (LLE) as a novel preconcentration technique. The principle of LPME is based on the distribution effect of the analytes between a microdrop of organic solvent and aqueous sample solution. LPME overcomes many shortcoming of traditional LLE method. This technique belongs to the green analytical technique and suitable to the development of micromation of modern analytical science.Recently, a novel, high performance and powerful preconcentration method microextraction technique termed as dispersive liquid-liquid microextraction (DLLME) has been developed by Assadi and co-workers. It is based on ternary component solvent system such as homogeneous liquid-liquid extraction (HLLE) and cloud-point extraction (CPE) . The advantages of DLLME and HLLE method are simplicity of operation, low consumption of organic solvents, high recovery and enrichment factor. Since the methods were first introduced, they have been successfully applied for the extraction of some organic and inorganic analytes in environmental matrices. The methods to detect residus of PAHs and PYR compounds in environmental matrices have been set up. The main contents are listed as follows:Firstly, DLLME combined with high performance liquid chromatography- fluorescence detector (HPLC-FLD) has been applied to the analysis of PAHs in water, fruit juices and vegetables. Under the optimum conditions, the linear range was 0.01-100μg L^-1, coefficients of correlation (r²) ranged from 0.9993 to 0.9998, and the enrichment factors ranged from 296 to 462. The relative standard deviations (RSDs) were in the range of 1.0～11.5% (n = 3), and limits of detection were 0.001～0.01μg L^-1. The relative recoveries of water, fruit juice and vegetable samples were 74.90～122.4%, 80.80～123.0% and 65.5～119.3%, respectively.Secondly, HLLE combined with gas chromatography-electron capture detector (GC-ECD) has been applied to the lambda-cyhalothrin and cypermethrin residual analysis in soils of Aojiang. The linearity was observed in the range 0.015～7.5μg L^-1 for lambda-cyhalothrin and 0.0075～20μg L^-1 for cypermethrin. Coefficient of correlation (r²) ranged from 0.9996 to 0.9998. The recoveries were 77.10～91.60%, and the RSD values were between 2.3 and 4.5%, limits of detection for lambda-cyhalothrin and cypermethrin were 0.01 and 0.005μg L^-1 , respectively. The proposed method is very simple, convenient, inexpensive and suitable to the development of green analytical technique.Thirdly, Combination of major project of Wenzhou in Zhejiang Province, solid-phase extraction (SPE) combined with gas chromatography-electron capture detector (GC-ECD) has been applied to the PYR residual analysis in Aojiang river. The water sample was first enriched with C18, then eluted with hextane-acetone (9:1, V/V), GC-ECD was applied for determination after concentrating with the gentle nitrogen gas flow. The recoveries were 75.70%～110.0%, the correlation coefficient (r² ) ranged from 0.9992 to 0.9999, the RSD values were between 0.65 and 5.63%, and limits of detection (LOD) were 0.015～1.5μg L^-1.