Use of activated charcoal in a solid-phase extraction technique for analysis of pesticide residues in tomatoes

Abstract

No presente trabalho foram desenvolvidos métodos de extração e purificação a fim de determinar e monitorar as concentrações dos pesticidas organofosforados mais utilizados em tomates na grande Florianópolis. A técnica de EFS com carvão ativo foi utilizada para a purificação e recuperação dos pesticidas metamidofós, acefato, malation e paration metílico. Os solventes para a extração e eluição foram escolhidos após diversas análises, sendo que os melhores resultados foram alcançados através da extração dos pesticidas com acetato de etila e eluição com CH 2 Cl 2 -acetato de etila (7:3). A média recuperada dos analitos das matrizes fortificadas com 0,20 -0,60 µg g -1 variou entre 85,2 e 100 %, com coeficientes de variação entre 1,3 e 6,3 %. Os limites de detecção foram de 0,04 a 0,12 ng g -1 . O adsorvente carvão ativo mostrou-se eficiente para a purificação da matriz de tomate e para a recuperação quantitativa dos analitos, especialmente os mais polares.The present work describes extraction and purification methods that were developed to determine and to monitor the content of organophosphorus pesticides in tomato crops from the agricultural district of Florianópolis, Brazil. SPE technique with activated charcoal was used for purification and recovery of the pesticides methamidophos, acephate, malation and methyl parathion. The solvents used for sample extraction and elution were chosen after several comparative tests. Best results were achieved using ethyl acetate for extraction and dichloromethane -ethyl acetate (7:3) for elution. Average recoveries from the matrices fortified with 0.20 to 0.60 µg g -1 ranged from 85.2 to 100 % with overall coefficients of variation of 1.3 to 6.3 %. The limits of detection of the method varied between 0.04 and 0.12 ng g -1 . Activated charcoal demonstrated to be efficient for tomato matrix purification and for quantitative recovery of the analytes.

Sorption potential of Moringa oleifera pods for the removal of organic pollutants from aqueous solutions

“…Therefore, it is essential to monitor the environment to ensure that their levels may not increase beyond the tolerance levels [4], otherwise they may adversely affect the well being of animal and human life and cause certain physiological disorders and diseases [5]. Among the techniques used for the removal of these contaminants from surface and ground water are adsorption on activated carbon [6], and their photochemical decomposition by ultraviolet radiations [7]. All these processes are too costly to be adopted for practical purposes.…”

Cool Mist Scavenging of Gas-Phase Molecules

“…It is known from various liquid-liquid and liquid-solid extraction protocols that high S/V values can warrant high speed of extraction. For example, activated carbon 11 or nanoparticles 12 are commonly used for efficient concentration or removal of chemical species from liquids by adsorption, while emulsion droplets accelerate liquid-liquid extractions. 13 Assuming that the mist droplet diameter is ~5 μm (based on typical specifications of the ultrasonic mist generator): S = 7.9 × 10 -11 m 2 , V = 6.5 × 10 -17 m 3 , and S/V = 1.2 × 10 6 m -1 .…”

Modern Extraction Techniques for Pesticide Residues Determination in Plant and Soil Samples

“…On the other side, PSA sorbent proved to be effective in removing polar compounds and fatty acids, while the SAX is suitable for the removal of fatty and other organic acids and sugars (Okihashi et al, 2005). Activated charcoal proved to be a good solution for removal of pigments from tomato extracts (Kaipper et al, 2001), and cabbage and carrots (Wang et al, 2008), while the florisil gave good results in pyrethroids determination in lettuce, cabbage, cauliflower, carrot, green pepper and green beans (T. Chen & G. Chen, 2007), and metribuzin and quizalofop-p-ethyl in potato and soil samples (Hu et al, 2010). Diatomaceous earth was a good solution for neonicotinoids determination in apricot, peach, pear, celery and courgette (Di Muccio et al, 2006), and C18 cartridges for determination of various pesticides in strawberry, grape, lettuce, tomato (Juan-García et al, 2005) and carbamates in soil (Santalad et al, 2010).…”