The direct extraction of Pd(CN)4(2-) from alkaline cyanide solutions with dodecyl dimethyl-2-phenoxyethyl ammonium bromide (DDPB) was investigated. Several factors affecting extraction efficiency, including DDPB concentration, modifier content, equilibrium time, phase ratio (O/A), pH and palladium concentration in aqueous phase, were studied. The results indicated that nearly all of the Pd(II) (>98%) was transferred from the aqueous phase into the organic phase. N-pentanol was the most appropriate modifier for the extraction of Pd(CN)4(2-). Palladium can be separated efficiently by DDPB over base metals (Fe ,Co, Ni and Cu) from alkaline cyanide medium. The extraction was quite fast and equilibrium could be established within 3 min. Most of Pd(II) (>96%) in the organic phase could be stripped with ammonium thiocyanate aqueous solutions, from which elemental palladium could potentially be recovered by the addition of hydrazine hydrate. The organic phase after stripping can be recycled for a continuous extraction-stripping operation. The extraction mechanism can be deduced based on FTIR spectrum and slope analysis while the mechanism of stripping can be explained by the principle of minimum charge density and Le Chatelier's principle. The proposed method was applied to extract palladium from real cyanide leaching liquor of Pd flotation concentrate with satisfactory results.

Um novo método para determinação simultânea de cinco íons de metais pesados em água, alimentos e cabelo, usando-se cromatografia líquida de alta eficiência foi desenvolvido. Os íons de chumbo, cádmio, mercúrio, níquel e zinco foram derivatizados (pré-coluna) com 2-(2-quinolinil-azo)-4-metil-1,3-dihidroxidobenzeno (QAMDHB) para formar quelatos coloridos. A seguir, os quelatos Pb-QAMDHB, Cd-QAMDHB, Hg-QAMDHB, Ni-QAMDHB e Zn-QAMDHB foram enriquecidos pela extração em fase sólida, com cartucho de C18. O fator de enriquecimento de 100 foi obtido ao eluir os quelatos retidos no cartucho, com tetrahidrofurano (THF). Esses quelatos foram separados em uma coluna de análise rápida ZORBAX Stable Bound (4,6X50 mm, 1,8 µm) com 68% de metanol (contendo 0,05 mol L-1 da solução tampão de ácido acético-pirrolidina, pH 8,5, e 0,01 mol L-1 de CTMAB) como fase móvel, fluxo de 2,0 mL min-1, em um detector por um detector de arranjo de fotodiodos a 450 <FONT FACE=Symbol>~</FONT> 600 nm. Os quelatos Pb-QAMDHB, Cd-QAMDHB, Hg-QAMDHB, Ni-QAMDHB e Zn-QAMDHB foram separados completamente em 2,0 min. Os limites de detecção do chumbo, cádmio, mercúrio, níquel e zinco são 1,2 ng L-1, 1,0 ng L-1, 0,8 ng L-1, 1,6 ng L-1 e 1,9 ng L-1, respectivamente, nas amostras originais. Este método foi aplicado na determinação dos cinco íons desses metais pesados com bons resultados.

A new method for the simultaneous determination of five heavy metal ions in water, food and human hair by a rapid column high-performance liquid chromatography was developed. The lead, cadmium, mercury, nickel and zinc ions were pre-column derivatized with 2-(2-quinolinylazo)-4-methyl-1,3-dihydroxidebenzene (QAMDHB) to form colored chelates. Then the Pb-QAMDHB, Cd-QAMDHB, Hg-QAMDHB, Ni-QAMDHB and Zn-QAMDHB chelates were enriched by solid phase extraction with C18 cartridge. The enrichment factor of 100 was achieved by eluting the retained chelates from the cartridge with tetrahydrofuran (THF). These chelates were separated on a ZORBAX Stable Bound rapid analysis column (4.6X50 mm, 1.8 µm) with 68% methanol (containing 0.05 mol L-1 of pH 8.5 pyrrolidine-acetic acid buffer solution and 0.01 mol L-1 of CTMAB) as mobile phase at a flow rate of 2.0 mL min-1 using a photodiode array detector from 450-600 nm. The Pb-QAMDHB, Cd-QAMDHB, Hg-QAMDHB, Ni-QAMDHB and Zn-QAMDHB chelates were separated completely within 2.0 min. The detection limits of lead, cadmium, mercury, nickel and zinc are 1.2 ng L-1, 1.0 ng L-1, 0.8 ng L-1, 1.6 ng L-1 and 1.9 ng L-1, respectively in the original samples. This method was applied to the determination of these five heavy metal ions with good results.