Effect of hydrogen ion concentration on the determination of lead by solvent extraction and atomic absorption spectrophotometry

Abstract

of an isopotential point at Ed -0.03-0.05 V in the purified HCIO4, both in the successive cathodic and anodic disk potential scans. These IP's are surprisingly well developed. As has been shown by electrochemical mass spectrometry (38), an unknown organic impurity is adsorbed when the Pt disk electrode is held more cathodic than 0.5 V. This organic species can be desorbed simultaneously with the adsorption of strongly bonded adsorbed H, resulting in the IP in the cathodic scan. Seemingly, this impurity starts adsorbing with the desorption of H in the anodic disk electrode scan, = 0 rpm, resulting in the IP in the anodic disk scan. In unelectrolyzed solutions, especially at higher concentrations of HCIO4, simultaneous reduction/oxidation of other electroactive impurities interferes and IP's are either illdeveloped or disappear.The results of the above experiments showed that the commercially available oxyacids and NaOH we studied contain impurities which can be deposited on a Pt electrode at 0.5 < < -0.2 V. These impurities prevent Hadsorption, inhibit oxygen reduction, and can be oxidized simultaneously with Pt. However, these impurities can rapidly be removed by passing the solution through a bed of reduced Pt sponge held at a potential slightly anodic of bulk hydrogen evolution. ACKNOWLEDGMENTThe cooperation of J. Comeau in performing and evaluating the electrochemical mass spectrometric study is acknowledged.

Masking, chelation, and solvent extraction for the determination of sub-parts-per-million levels of trace elements in high iron and salt matrixes

“…Several extractants for the photometric determination of Au in complex materials have been reported (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). These extractants possess a variety of structures, capable of forming ion pair complexes of Au with cyano, halo, nitrato, sulfato, and other anions providing a hydrophobic outer layer which facilitates its transfer to the organic phase.…”

“…It was also reported for simultaneous extraction and spectrophotometric determination of Au, Pd, and Pt from halide media (7). Furthermore, thioorganic compounds, e.g., 2-mercaptobenzothiazole, pyrimidinethiol, and others, may be applied for the extraction and spectrophotometric determination of Au(III), but platinum metals seriously interfere (3,4,(8)(9)(10).…”

“…These reagents fulfill certain basic requirements, i.e., sufficient extraction power, rapid phase separation, sufficient chemical stability, and selective color reaction. Due to the high selectivity, these compounds are superior to those mentioned above (1)(2)(3)(4)(5)(6)(7)(8)(9)(10).…”

Cromatografia de afinidade por íons metálicos imobilizados (IMAC) de biomoléculas: aspectos fundamentais e aplicações tecnológicas

“…Em 1974, Everson e Parker demonstraram que íons metálicos presentes em metaloproteínas são os principais responsáveis pela adsorção dessas em resinas contendo quelantes imobilizados e exploraram esta afinidade na separação deste tipo de proteínas. 1 A técnica proposta por Everson e Parker popularizou-se com o trabalho publicado por Porath e colaboradores em 1975, quando os autores introduziram o termo cromatografia de afinidade por íons metálicos imobilizados (Immobilized Metal-Ion Affinity Chromatography -IMAC). 2 IMAC explora a interação entre espécies doadoras de elétrons presentes na superfície de biomoléculas em solução e íons metálicos quelatados imobilizados em um suporte sólido.…”

The Effect of Ammonium Pyrrolidinedithiocarbamate (APDC) Complexing Agent on the Determination Of Copper Trace in Steel Using Atomic Absorption Spectrophotometry

“…Ammonium pyrrolidined-ithiocarbamate (APDC) was first investigated by Malissa and Schoffmann in 1955. 1 The combination of APDC as a chelating agent and methyl isobutyl ketone (MIBK) as an organic solvent in atomic absorption spectrophotometry has been reported by a number of authors [2][3][4][5][6][7] and some 4,7 found it the most useful extraction system, because APDC forms stable chelates with numerous metal over a wide pH range and MIBK exhibits ideal combustion properties in the flame. A number of advantages results from the extraction of APDC-metal complexes into a suitable organic phase.…”