O presente trabalho descreve um procedimento para emulsificação-microextração de quantidades traço de íons cobalto e manganês sem uso de ligantes, assistido por ultrasom, em amostras de água. Os metais extraídos foram determinados por espectrometria de absorção atômica em chama (FAAS). Foram estudados e otimizados diversos fatores que influenciam a eficiência de extração de íons cobalto e manganês, tais como tipo e volume do solvente de extração, pH, tempo de extração, temperatura de extração e força iônica. Íons cobalto e manganês foram extraídos em um meio emulsificado acusticamente com 20,0 mL de tetracloreto de carbono. Os limites de detecção foram 0,8 e 0,5 ng mL -1 para Co(II) e Mn(II), respectivamente (3 S b /m). Oito determinações em replicata de uma mistura de 100,0 ng mL -1 de cobalto e 50,0 ng mL -1 de manganês resultaram em absorbâncias média de 0,055 e 0,061 com desvios padrão relativos de 3,2% e 2,9%, respectivamente. O procedimento proposto foi aplicado com sucesso na determinação de cobalto e manganês em amostras de água.The present work reports a procedure based on ligandless-ultrasound-assisted emulsificationmicroextraction of trace amounts of cobalt and manganese ions in water samples prior to flame atomic absorption spectrometry determination (FAAS). Different factors influencing the extraction efficiency of cobalt and manganese ions, such as type and volume of the extraction solvent, pH, extraction time, extraction temperature, and ionic strength were studied and optimized. Cobalt and manganese ions were extracted in an acoustically emulsified media by 20.0 µL carbon tetrachloride. The limits of detection were 0.8 and 0.5 ng mL -1 for Co(II) and Mn(II), respectively (3S b /m). Eight replicate determinations of a mixture of 100.0 ng mL -1 cobalt and 50.0 ng mL -1 manganese gave a mean absorbance of 0.055 and 0.061 with relative standard deviations of 3.2 and 2.9%, respectively. The proposed procedure was successfully applied to determination of cobalt and manganese in water samples.

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In this work, silver iodide (Ag(I)) ions were separated via carrier element-free coprecipitation (CEFC) method by using an organic coprecipitating agent, 1,6-diamino-4-(4-chlornphenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile [DCODD] prior to its determination by flame atomic absorption spectrometry (FAAS). Analytical parameters including pH of aqueous solution, amount of DCODD. Standing time, centrifugation rate and time, and sample volume were studied and optimized. Under the best experimental conditions, it was found that extraction can be performed from the sample volume of 500.0 for silver ion (preconcentration factor of 100.0). Linearity was maintained between 0.006-1.50 µg.mL −1 for silver. Detection limit for silver based on 3Sb was 1.60 ng.mL −1 . The relative standard deviation of eight replicate measurement of 0.20 Downloaded by [University of Cambridge] at 00:38 11 June 2016A c c e p t e d M a n u s c r i p t 2 µg.mL −1 of silver was 2.10%. Finally, the developed method was successfully applied to extraction and determination of the silver ions in the Lepidium draba L plant, water and standard samples and satisfactory results were obtained.