Application Of Liquid Phase Microextraction Techniques For The Analysis Of Organic Pollutant Residues

The organochlorine pesticides and chlorophenols are two types of organic pollutants which are widely used in industrial and agricultural production. Although these two types of pollutants can promote the development of China’s industry and agriculture, they can cause great damage to human beings who were at the end of the food chain since they are highly toxic, and can be enriched through the food chain. Traditional analytical methods for organochlorine pesticides and chlorophenols such as liquid liquid extraction and solid phase extraction are time-consuming, ofen use large amounts of organic solvent, and could cause secondary pollution to the environment. Therefore, it is necessary to develop rapid, efficient, and simple methods for the detection of organochlorine pesticides and chlorophenols organic pollutants.Liquid phase microextraction (LPME) is proposed in recent years as a new sample pre-treatment technology, which combines extraction, purification and enrichment in one step. LPME has advantages of fastness, simplicity of operation and low cost. Meanwhile, only microlitre organic solvent is used to extract target analytes from sample solution, which is friendly to environment.In headspace single drop microextraction, the extractant microdrop was suspended at the tip of a microsyringe needle which was fixed in the headspace of the sample solution. Analytes volatile to the headspace of sample vial by heating and stirring and extracted by the extractant. After extraction, the microdrop is retracted back into the microsyringe and transferred to chromatography and electrophoresis for further analysis. This method can avoid interference from complicated matrix and is very suitable for the determination of volatile and semi-volatile substances in complex matrix. Dispersive liquid liquid microextraction (DLLME) is also a new kind of liquid-phase micro-extraction method. In this method, the mixture of extractant and dispersant was injected into the sample solution. The extractant dispersed into many small droplets which could increase the contact area between analytes and exraction solvent. It is possible to complete the extraction in a very short time and the enrichment factor is also higher. This paper used dispersive liquid-liquid microextraction and improved liquid phase microextraction method to study the pre-treatment of organochlorine pesticides and chlorophenols residues, the main research contents are as follows:1. Dispersive liquid-liquid microextraction method was used for the determination of20organochlorine pesticide residues in19sampling points of Danjiangkou Reservoir. Several parameters including the type and volume of extractant, the type and volume of dispersant, ionic strength were studied and optimized. Under the optimal conditions, the detection limits of the organochlorine pesticides were1.7-120ng L-1. The method was applied to the detection of organochlorine pesticides residues in real reservoir water and pore water samples, some kinds of organochlorine pesticides have been detected.2. The possibility of the combination of ultrasound-assisted extraction (UAE) and synchronous derivative DLLME coupled to GC-ECD for extraction, preconcentration, clean-up and analysis of three CPs in toilet paper was investigated. Several critical variables affect the UAE-synchronous derivative DLLME performance, including type and volume of ultrasonic extraction solvent, type of extraction and dispersive solvent, and their volumes for DLLME, amount and volume of derivatization reagent, pH value and ionic strength, were systematically investigated. Under the optimal conditions, the detection limits were0.25-1.5μg kg-1. To the best of our knowledge, this is the first paper that focused on the analysis of chlorophenol residues in toilet paper.3. A new kind of liquid-phase microextraction device was designed on the basis of the traditional headspace microextraction device. This device not only overcame the drawbacks of traditional headspace microextraction device such as the easy falling off and the small volume of organic extractant, but also kept its advantages of avoidness of complex matrix interferences. The device also has advantages of rapid mass transfer rate and could realize dynamic extraction. The device was also applied for the determination of chlorophenol residues in environmental water samples, the detection limits were0.001-0.013ng mL-1.