An effective, simple, low cost and accurate sorption-spectrophotometric platform for the extractions and subsequent quantifications of Cd(II) and Pb(II) ions in food and environmental samples has been described in this dissertation. The separation and preconcentration of the analyte ions were accomplished by solid phase extraction method based on the adsorption of their N-(4-methylphenyl)-2-{[(4-phenyl-5-pyridin-4-yl-H-1,2,4-triazol-3-yl)thio]acetyl} hydrazinecarbothioamide (MFPTAHK) complex on Amberlite XAD-8 resin in a mini column. The developed method was systematically investigated in different set of experimental parameters that influence the separation and preconcentration of Cd(II) and Pb(II) ions. The precision of the method was determined by reproducibility studies and expressed as relative standard deviations (RSD %) which were less than 4% for both analyte ions. The limits of detections (LODs) for Cd(II) and Pb(II) ions based on the three times the standard deviation of the blanks (N:10) were found to be 0.31 μg L-1 and 0.86 μg L-1, respectively. The developed SPE procedure was utilized for the simultaneous extraction and determinations of Cd(II) and Pb(II) ions levels in rice, cracked wheat and red lentil as food samples and various 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 new solid phase extraction (SPE) method has been developed for the selective separation and preconcentration of Cu (II) ions in food and water samples prior to its flame atomic absorption spectrometry determination. The method is based on the adsorption of the Cu(II) - 2-{[4-Amino-3-(4-methylphenyl-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]acetyl}-N-phenyl hydrazinecarbothioamide complex on Amberlite XAD-8 resin. The metal complex retained on the resin was eluted with 7.5 mL of 2.0 mol L-1 HCl in acetone. The optimum conditions for the SPE of Cu(II) ions were investigated, and the method was subsequently applied to sea water, stream water, rice, tea, and tobacco samples for the determination of Cu(II) levels.