Desenvolvimento de uma metodologia analítica com microextração líquido-líquido para determinação de agroquímicos organofosforados em água

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Many organic agro-chemicals residues are presented in low concentrations waters. Due to this, has been increasing the interest on the development of sample preparation techniques that give the possibility of analits pre concentration present in the matrix to adjust in the detection system. In this work, was used analytical method, the liquid-liquid microextraction, using the modified Murray`s extraction bottle to extract the contamination agents, using hexane as extraction solvent, being later applied in samples of natural water. The analysed and studied organophosphorated agrochemicals were: dissulfoton, paration methyl, chloryirifos and fenchlorfos. The Gas Chromatography with Mass Spectrometry Detection (GC-MS) was used for the agrochemicals identification. The volume of the sample used in the extraction was 1000mL. Significant parameters like: the agitation time, the pH, the ionic strength, the way and time of the system`s agitation were tested and valued in the analits pre concentration was carried analitos it was carried out with the best agitation time of 10 minutes. The addition of 2,0 mol/L of sodium chloride salt (NaCl), improved the recovery results for all the agro-chemicals in comparison with the concentration range from 0,1 to 3,0 mol/L. Another important factor in the comparison was the pH range used, which was adjusted with hydrochloric acid (HCl) to 5,0 pH once that in alkaline solution the instability of the molecules takes place. In the chromatography separation, good results for the retention times were obtained, being in a rate between 15.239 to 16.893 minutes. The limits of detection and quantification were between 0,083 to 0,756 μg/L-1 and 0,254 to 2,292 μgL-1, respectively. The developed method allowed the determination of the agrochemicals in study in rate of until 21 per cent in samples of water Várzea in river

ASSUNTO(S)

quimica microextração líquido-líquido agro-chemicals agroquímicos compostos orgânicos; análise cromatográfica; extração (química) liquid-liquid microextraction water água

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