Environmental friendly methods for the extraction and determination of organophosphorus and organochlorine pesticides

Abstract

Organochlorine pesticides have been used during decades as insecticides and for the control of vector-borne diseases. In 1980s these pesticides were banned in developed countries and were replaced by other kind of compounds like organophosphorus pesticides; however, they are usually more toxic than organochlorine pesticides. Nowadays these compounds are present in the environment; thus the long-term persistence and their metabolites are presented in water, sediments, soils and vegetables. The methods usually used for the extraction of these compounds from environmental samples are often too time consuming, involve multi-step procedures that are prone to loss of analytes and use high amounts of toxic organic solvents. Modern strategies in analytical chemistry have been developed towards the simplification of sample's preparation, as well as the minimization of organic solvent used on the extraction process. An alternative to organic solvents is the use of micellar systems as extractants of organic pollutants in liquid and solid environmental samples. Micellar media facilitate the solubilization of different compounds present in different kind of samples. Benefits obtained when micellar media are used, are lesser toxicity and cost than organic solvents. Cloud-point extraction (CPE) process in liquid samples and microwave assisted micellar extraction (MAME) in solid samples, have been developed for the extraction of pesticides prior to their determination by high performance liquid chromatography. Moreover, during extraction process, many interfering components are usually co-extracted from solid samples together with target analytes. For increasing sensitivity and selectivity, MAME procedure can be coupled with other extraction and preconcentration techniques, introducing a clean-up step for removing substances that could interfere with the final determination of target analytes in HPLC system. This coupling can be done with solid phase microextraction (SPME), called MAME-SPME, and with solid phase extraction (SPE), MAME-SPE, producing also an intensification of the analytes signals by means of extract clean-up and preconcentration. In this study an overview of the use of micellar systems well alone, or well combined with the aforementioned extraction/preconcentration techniques, for the determination of organochlorine and organophosphorus pesticides in liquid and solid samples is presented. Fundaments, experimental, variables optimization, quantitative procedures and applications are described and discussed, making emphasis on the advantages of these green methodologies with regard to traditional extraction techniques.