Multiresidue methods for determination of pesticides using SPME and SPE followed by GC-NPD system: a comparative study

Abstract

Neste estudo, métodos multirresíduos usando extração em fase sólida (SPE) e microextração em fase sólida (SPME) são comparados na determinação de pesticidas em amostras aquosas. Parâmetros como tipo de fibras e espessura, solvente de eluição, volume da amostra, tempo de equilíbrio, coeficiente de partição e solubilidade foram investigados. Resultados satisfatórios foram obtidos para a análise de pesticidas usando cartuchos C18 e acetato de etila como eluente, com taxas de recuperação entre 75-107%. As melhores condições para SPME foram com uma fibra PDMS 100 µm de espessura, volume de amostra de 40 mL, e tempo de equilíbrio de 45 min. O método SPME é o mais adequado para a análise de pesticidas em água, devido à sua rapidez e simplicidade e ao não uso de solventes. Os limites de detecção e quantificação são inferiores aos limites de concentração máximos estabelecidos pelas autoridades brasileiras, sendo portanto aceitável.In this study, multiresidue method using solid phase extraction (SPE) and solid phase microextraction (SPME) are compared in the determination of pesticides in aqueous samples. Parameters such as fiber type and thickness, elution solvent, sample volume, equilibration time, partition coefficient and solubility were investigated. Satisfactory results were obtained for the analysis of pesticides using C18 cartridges and ethyl acetate as eluent, whith recovery rates between 75-107%. The best conditions for SPME fiber were PDMS with a 100 mm thick, sample volume of 40 mL, and reaction time was 45 min. SPME method is most suitable for the analysis of pesticides in water, due to its speed and simplicity and solvent-free. The limits of detection and quantification are below the maximum concentration limits established by Brazilian authorities and therefore acceptable.Keywords: pesticides, SPME, water analysis, microextraction, partition coefficient IntroductionThe protection of water quality is a real concern of government agencies that control public health. The worldwide intensive use of pesticides plays a key role in environmental contamination, especially in water resources. In the last years, Brazil has been considered the largest consumer of pesticides in the world. 1 Only in 2009, around 1 million ton of pesticides were sold in the country,mainly applied in soybean, corn, sugarcane and cotton cultures. 1 According to ANDEF, there were about 475 active ingredients and 1278 products registered. 2 Pesticides that remain in the environment or reach the aquatic systems pose risks to animal species by their toxicity and ability to bio-accumulate along the food chain. 3 The European Community has set the value of 0.1 mg L -1 for any individual pesticide and 0.5 mg L -1 for the total pesticide residues of pesticides. In Brazil, the maximum concentrations of pesticides in water are regulated by the Administrative Rule No. 518/2004 (drinking water) of the Milhome et al. 2049 Vol. 22, No. 11, 2011 Ministry of Health, by The National Environment Council (CONAMA) Resolution No. 357/2005(classification o...

Resíduos de pesticidas em águas superficiais de área de nascente do Rio São Lourenço-MT: validação de método por extração em fase sólida e cromatografia líquida

“…Trabalhos análogos ao apresentado que visam o desenvolvimento de métodos analíticos adequados para a determinação simultânea de vários princípios ativos, [51][52][53][54] assim como sua posterior aplicação em amostras de água, 51,52,54 têm sido evidenciados com frequência na literatura.…”

Determination of Pesticides in Grape Juices by QuEChERS and Liquid Chromatography-Tandem Mass Spectrometry

“…The frequent changes in the manufacture of pesticides and the discovery of new active ingredients of different classes make it difficult to monitor and control such residues, requiring constant improvement of the analytical methods. 31,32 Thus, it is necessary to develop new and effective methods. In addition, this method was focused in pesticides, which were widely used in grape juice culture in Brazil, and the method is validated according INMETRO (Instituto Nacional de Metrologia Qualidade e Tecnologia), which is the Brazilian organization responsible for quality assurance.…”

“…31,34,35 Method precision was evaluated using CVs. [31][32][33][34][35] Seven blank grape juice samples were independently fortified at 0.005, 0.1 and 2 mg L -1 and prepared by two technicians (technician 1 and technician 2). Then, CVs for 25 pesticides were evaluated by each technician are shown in Table 6.…”

Comparison between GC-MS-SIM and GC-ECD for the determination of residues of organochlorine and organophosphorus pesticides in Brazilian citrus essential oils

“…Barrek et al 18 using GC-MS-SIM obtained recoveries from 79 to 84% for organochlorine and from 88 to 93% for organophosphorus in pesticide analyses of citrus EO using Florisil ® SPE. Milhome et al 19 studied the determination of pesticides (multiresidue method) using SPE C18 in aqueous samples and obtained a recovery of 86.8% for chlorpyrifos and 92.1% for methyl parathion. Zuin et al 20 using GC-ECD obtained recovery values of 72 to 111% for organochlorine and organophosphorus pesticides.…”