A dispersive liquid-liquid microextraction procedure coupled to spectrophotometry is described for the determination of the trace levels of Sudan Blue II. Analytical parameters, such as pH, volume of extraction solvent (carbon tetrachloride), volume of dispersant (ethanol), volume of sample, and extraction time, were optimized. Matrix effects were also investigated. Preconcentration factor was found to be 200. Detection limit and relative standard deviation (RSD) were 0.55 µg L-1 and 3.9%, respectively. The procedure was successfully used for the determination of trace levels of Sudan Blue II in food, ink, antifreeze, and industrial waste-water samples.

Um procedimento de extração em fase sólida (SPE) altamente sensível, seletivo e de baixo custo foi desenvolvido para separação e enriquecimento de íons Au(III) em amostras ambientais previamente a sua detecção por espectrometria de absorção atômica com chama (FAAS). O complexo Au(III)-2-piridina-5-(4-toluil)-1,3,4-oxadiazol (PYTOX) foi quantitativamente adsorvido em resina Amberlite XAD-4 na condição de HNO3 0,5 mol L-1 e a eluição foi realizada com 7,5 mL de HCl 1,0 mol L-1 em acetona. Alguns parâmetros analíticos afetam as recuperações de íons Au(III), tais como concentração de HNO3 da solução da amostra, quantidade de PYTOX, tipo, concentração e volume do eluente, volume de amostra e concomitantes. Sob condições experimentais ideais, o limite de detecção para Au(III) foi 1,03 µg L-1, com fator de pré-concentração de 50 e desvio padrão relativo (RSD) de 3,7%. A determinação de íons Au(III) em resíduo anódico, minério de ouro, solo e águas de mar e de rio foi efetuada após verificação da exatidão do método por testes de adição e recuperação.

A highly sensitive, selective and low cost solid phase extraction (SPE) procedure was developed for separation and enrichment of Au(III) ions in environmental samples prior to its flame atomic absorption spectrometric detection. Au(III)-2-pyridin-5-(4-tolyl)-1,3,4-oxadiazole (PYTOX) complex was adsorbed quantitatively on Amberlite XAD-4 resin in 0.5 mol L-1 HNO3 condition and the elution was carried out with 7.5 mL of 1.0 mol L-1 HCl in acetone. Some analytical parameters, affect the recoveries of Au(III) ions, such as HNO3 concentration of sample solution, amount of PYTOX, type, concentration and volume of eluent, sample volume and concomitants were examined. Adopting optimized experimental conditions, the limit of detection for Au(III) ions was 1.03 µg L-1 with preconcentration factor of 50 and a relative standard deviation (RSD) of 3.7%. The determination of Au(III) ions in anodic slime, gold ore, soil and sea and stream waters was performed after checking the accuracy of the method by addition-recovery tests.

A simple cloud point extraction procedure is presented for the preconcentration of copper in various samples. After complexation by 4-hydroxy-2-mercapto-6-propylpyrimidine (PTU), copper ions are quantitatively extracted into the phase rich in Triton X-114 after centrifugation. Methanol acidified with 0.5 mol L-1 HNO3 was added to the surfactant-rich phase prior to its analysis by flame atomic absorption spectrometry (FAAS). Analytical parameters including concentrations for PTU, Triton X-114 and HNO3, bath temperature, centrifugation rate and time were optimized. The influences of the matrix ions on the recoveries of copper ions were investigated. The detection limits (3SDb/m, n=4) of 1.6 ng mL-1 along with enrichment factors of 30 for Cu were achieved. The proposed procedure was applied to the analysis of environmental samples.

A solid phase extraction procedure using Amberlite XAD-1180/Pyrocatechol violet (PV) chelating resin for the determination of iron and lead ions in various environmental samples was established. The procedure is based on the sorption of lead(II) and iron(III) ions onto the resin at pH 9, followed by elution with 1 mol/L HNO3 and determination by flame atomic absorption spectrometry. The influence of alkaline, earth alkaline and some transition metals, as interferents, are discussed. The recoveries for the spiked analytes were greater than 95%. The detection limits for lead and iron by FAAS were 0.37 µg/L and 0.20 µg/L, respectively. Validation of the method described here was performed by using three certified reference materials (SRM 1515 Apple Leaves, SRM 2711 Montana Soil and NRCC-SLRS-4 Riverine Water). The procedure was successfully applied to natural waters and human hair.