Técnicas de preparo de amostra empregadas na determinação de agrotóxicos carbamatos em água e solo

Abstract

ResumoAtualmente, dentre os diferentes tipos de agrotóxico aplicados na agricultura, os carbamatos têm se destacado em virtude de sua elevada eficiência, facilidade de síntese e baixo custo. No entanto, o uso desregrado desses agrotóxicos, não seguindo as Boas Práticas Agrícolas (BPA), tem levado à contaminação do meio ambiente, destacando-se o acúmulo desses compostos nas águas superficiais (rios e lagos), subterrâneas e no solo. Além disso, muitos desses agrotóxicos são tóxicos para os seres vivos, principalmente por inibirem a ação de enzimas biológicas, como as colinesterases. Nesse contexto, o monitoramento de resíduos de agrotóxicos no solo e nas águas tornou-se imprescindível para a redução do impacto ambiental e aumento da segurança da saúde humana e animal, sendo realizado através da confirmação e quantificação desses resíduos, empregando-se diferentes técnicas analíticas. As técnicas de preparo de amostra mais empregadas e modernas para determinação analítica de resíduos de agrotóxicos carbamatos serão abordadas neste artigo. Palavras-chavePreparo de amostra; carbamatos; água; solo. Sample preparation techniques for determination of carbamate pesticides in water and soil AbstractCurrently, among the several kinds of pesticides employed in agriculture, carbamates have been widely used because of their high efficiency, ease of synthesis and low cost. However, the unjudicious use of these pesticides, not following Good Agricultural Practices, can have adverse effects on the environment, especially the accumulation of these compounds in surface waters (rivers and lakes), groundwater and soil. Furthermore, many of these pesticides are toxic to humans and animals, mainly due to their inhibition of enzymes, like cholinesterases. In this context, the monitoring of pesticide residues in soils and waters has become essential to reduce the environmental impact and improve the safety of human and animal health, being performed through the confirmation and quantification of these residues, employing different analytical techniques. The most frequently used techniques and modern sample preparation for analytical determination of carbamate pesticide residues will be discussed in this paper.

An overview of the main foodstuff sample preparation technologies for tetracycline residue determination

“…Like the microwave-assisted extraction (MAE), UAE was developed as an alternative to Soxhlet extraction. The merits of the UAE are that it is relatively faster and requires smaller amounts of solvent [47,85].…”

“…In addition, several extractions can be performed simultaneously and no expensive or specialized apparatus are required. One will note, however, that since the selectivity and enrichment capabilities of this technique are limited, further sample preparation steps are usually required to determine trace contaminants in foods [12,47,85]. By virtue of that, UAE is usually combined with other clean-up and/or preconcentration methodologies as an additional extraction process aiming at improving extraction efficiency.…”

“…In this technique, the extraction takes place inside the lumen of the polypropylene porous hollow fiber, which contains the microvolume of the extracting liquid. This ensures that the extracting liquid is not in direct contact with the sample solution [85].…”

“…To expedite the extraction, the sample can be extensively heated, agitated or stirred. The analytes are then extracted from the aqueous sample (donor phase) through the organic layer on the walls of the hollow fiber and then placed into an acceptor phase inside the lumen of the hollow fiber [85,133,135]. Fig.…”

“…In this sense, one is able to prevent the possibility of the analytes returning to the organic phase and thus to the donor solution, favoring their extraction. In this method, the pH adjustment plays a central role [85,133,135].…”