Comparison of Various Carbon Adsorbents and Quantitative Elution and Separation of Forty-two Pesticides from a Carbon-Solka Floe Cleanup Column

Abstract

Ten different carbons were investigated as adsorbents in a column cleanup procedure for extracts of lettuce and carrots. Organochlorine pesticides were eluted with 175 nil of 1.5% acetonitrile in hexane. The quantitative elution of 13 pesticides as a mixture with and without the presence of carrot or lettuce extract was determined by gas-liquid chromatography (GLC) with electron capture detection (ECD). The mean recovery values for each pesticide from all carbons, excluding Norit A neutral, ranged from 87 to 106% with a coefficient of variation (C) of 3 to 11. In the presence of plant extracts the individual pesticide recoveries for 6 carbons ranged from 75 lo 99% with a C of 6 to 16. All pesticides from 9 individual carbons had mean recovery values ranging from 93 to 108% with a C of 5 to 10. In the presence of plant extracts these values were 81 to 100% with a C of 8 to 12. Four carbons (Darco G60, Darco S51, Nuchar C-190N, Norit FQP) were considered satisfactory in the cleanup procedure. The procedure was applied to quantitative elution of 42 pesticides representing insecticides, fungicides, and herbicides from a Darco G60-Solka Floe cleanup column. The mean per cent recoveries (3 determinations) ranged from 82 to 112 with C from 2 to 10 for 38 compounds. The mean per cent recovery of EPN was 108 with a C of 13. The per cent recoveries of three compounds were considered low: Thimet 72, Daconil 73, and Guthion 77. Twenty of the pesticides as three mixtures containing 2, 4, and 14 compounds were added to plant extracts of carrots, potatoes, wheat, and pineapples. The mean per cent recovery values ranged from 81 to 108 with a C range of 2 to 10 for 17 compounds

Resíduos de Pesticidas Organoclorados em Alimentos Gordos — revisão da metodologia analítica, II. Processos de purificação

“…Samuel [56] utilizou o carvão activado misturado com óxido de alumínio, celite, sulfato de sódio e attapulgus clay para purificar diferentes tipos de extractos. Embora Mukherjee e colaboradores [50] ao efectuarem o estudo da eficiência de várias colunas com diferentes adsorventes tenham verificado que o carvão activo se mostrou mais eficaz na remoção de pigmentos e gorduras, McLeod e colaboradores [44] ao estudarem dez tipos diferentes de carvão verificaram que a sua capacidade de retenção para ceras e óleos não era tão elevada quanto para os pigmentos. Adachi e colaboradores [1] estabeleceram um método para a análise de amostras de leite procedendo à purificação com 0,5 g de carvão activado contido em minicolunas de 15 mm de d.i.…”

Carbon dispersed in glass fibers as an adsorbent for contaminant enrichment and fractionation

“…Activated carbon, the age-old purifier, continues to offer expanded applications in the treatment of municipal and industrial wastes, in the recovery and purification of synthetic and natural substances, and in numerous other chemical and environmental processes (1)(2)(3). New applications of activated carbons in the separation and purification of organic compounds are largely the result of the availability of more sophisticated preparations of activated carbons possessing more refined chemical and physical properties (3)(4)(5)(6)(7). Research at the Columbia National Fisheries Research Laboratory has shown that the application of the uniquely selective adsorptive properties of certain activated carbons to the purification of organic compounds can be seriously limited by the development of high back-pressure in chromatography columns packed with finely divided carbon and by poor recoveries of strongly absorbed substances, even from sub-gram quantities of carbon.…”

Pesticide residues

“…McLeod and cow-orkers (151) Watts and Storherr {229) continued their studies of the sweep codistillation cleanup procedure. They described a cleanup of milk solvent extract for the determination of organophosphate and chlorinated hydrocarbon pesticides.…”