Optimization and validation of the solid-liquid extraction technique for determination of picloram in soils by high performance liquid chromatography

Abstract

-The objective of this study was to optimize and validate the solid-liquid extraction (ESL) technique for determination of picloram residues in soil samples. At the optimization stage, the optimal conditions for extraction of soil samples were determined using univariate analysis. Ratio soil/solution extraction, type and time of agitation, ionic strength and pH of extraction solution were evaluated. Based on the optimized parameters, the following method of extraction and analysis of picloram was developed: weigh 2.00 g of soil dried and sieved through a sieve mesh of 2.0 mm pore, add 20.0 mL of KCl concentration of 0.5 mol L -1, shake the bottle in the vortex for 10 seconds to form suspension and adjust to pH 7.00, with alkaline KOH 0.1 mol L -1. Homogenate the system in a shaker system for 60 minutes and then let it stand for 10 minutes. The bottles are centrifuged for 10 minutes at 3,500 rpm. After the settlement of the soil particles and cleaning of the supernatant extract, an aliquot is withdrawn and analyzed by high performance liquid chromatography. The optimized method was validated by determining the selectivity, linearity, detection and quantification limits, precision and accuracy. The ESL methodology was efficient for analysis of residues of the pesticides studied, with percentages of recovery above 90%. The limits of detection and quantification were 20.0 and 66.0 mg kg -1 soil for the PVA, and 40.0 and 132.0 mg kg -1 soil for the VLA. The coefficients of variation (CV) were equal to 2.32 and 2.69 for PVA and TH soils, respectively. The methodology resulted in low organic solvent consumption and cleaner extracts, as well as no purification steps for chromatographic analysis were required. The parameters evaluated in the validation process indicated that the ESL methodology is efficient for the extraction of picloram residues in soils, with low limits of detection and quantification.Keywords: ESL, testing, waste, herbicide.RESUMO -O objetivo deste trabalho foi otimizar e validar a técnica extração sólido-líquido (ESL) para a determinação de resíduos do herbicida picloram em amostras de solos. Na etapa de otimização, as condições ideais para extração em amostras de solo foram determinadas de forma univariada. Foram avaliados a proporção solo/solução extratora, o tipo e tempo de agitação, a força iônica e o pH da solução extratora. A partir dos parâmetros otimizados, a seguinte metodologia de extração e análise do picloram foi desenvolvida: pesar 2,00 g de solo seco ao ar e passado por uma peneira de malha de 2,0 mm de poro, adicionar 20,0 mL de solução de KCl na concentração de 0,5 mol L -1 , agitar o frasco em agitador vortex por 10 segundos para a formação da suspensão e ajustar o pH desta para 7,00, com solução alcalina KOH 0,1 mol L -1 . Homogeneizar o sistema em agitador vertical por 60 minutos e, posteriormente, deixar em repouso por 10 minutos. Em seguida, os frascos são centrifugados por 10 minutos a 3.500 rpm. Após decantação das partículas do solo e limpeza do extrato sobrenadante, ...

A simple and rapid analytical methodology based on liquid chromatography-tandem mass spectrometry for monitoring pesticide residues in soils from Argentina

“…The method presented satisfactory precision (RSD<20%) and accuracy (recoveries between 70 and120%) for all analytes, at the two levels of fortification, with the exception of the herbicide picloram, whose recoveries were around 50%. Some authors also reported low recoveries for this weak acid herbicide when extracted from soils at pH lower than 7 6 . The QC samples for picloram in the soils tested had average recoveries between 47 and 60%, which was consistent with data obtained in method validation.…”

“…Particularly, soil organic matter has notable impact on analyses and therefore it is common the inclusion of clean-up steps in the analytical procedure for its removal, even using powerful analytical techniques such as liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS) [5][6][7] .…”

Development and method validation for determination of 54 pesticides in Okra by LC-MS/MS analysis

“…The LOQ is the lowest spike level meeting the method performance criteria trueness and precision (70-120% and RSD ≤ 15%, respectively). Measure- FDA ., 1996;Wal ish, 2006;Assis et al, 2011).…”

Avaliação da ESL-PBT na determinação de carbaril em amostras de abacaxi pérola (ananás comosus) comercializadas no município de Itumbiara

“…Em contrapartida, outro método que foi desenvolvido e que tem sido utilizado com sucesso para determinação de agrotóxicos em alimentos e demais amostras por cromatografia é a extração sólido-líquido com partição em baixa temperatura (ESL/PBT) [20][21]. O método permite o desempenho simultâneo pela extração de agrotóxicos e limpeza dos extratos e inúmeros estudos também já foram realizados, sendo aplicado em amostras frutíferas e de origem vegetal, como na batata [22], cenoura [23], abobrinha [24], alface [25], alho [26], milho [27], tomates [28], cajá-manga [29], pimentão [30] e aplicado em amostras de solos [31][32][33]. O método é simples, eficiente, oferece praticidade, baixo consumo de solvente orgânico e amostra, número reduzido de etapas e confiabilidade com porcentagens de recuperação elevadas e boa repetitividade [34].…”