1,2,4,6-Tetraphenylpyridinium perchlorate as a reagent for ion-association complex formation and its use for the spectrophotometric determination of gold

• Published in: Microchemical journal 1984-01, Vol.30 (1), p.71-78
• Main Authors: ORTUNO, J. A, PEREZ-RUIZ, T, SANCHEZ-PEDRENO, C, MOLINA BUENDIA, P
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Spectrometric and optical methods
• ISSN: 0026-265X; 1095-9149
• DOI: 10.1016/0026-265X(84)90139-5

The synthesis, characteristics, and applications of 1,2,4,6-tetraphenylpyridinium perchlorate (TPPP) as an agent that forms ion-association complexes is described. This new spectrophotometric analytical reagent forms with AuCl 4 −1 a 1:1 complex which is slightly soluble in water and can be extracted with isopentyl acetate, with maximum absorbance 313 nm, molar absorptivity 3.44 × 10 4 liters mol −1 cm −1. The variables involved in the formation and extraction of the complex in the mentioned organic solvent are studied. In the selected conditions, 1 M hydrochloric acid medium, the extraction efficiency was 95.3%. The apparent stability constant of the complex is log K = 5.9 ± 0.1 at 20 °C. The extracted complex is useful for the spectrophotometric determination of gold in the range of 0.05 to 0.5 ppm. Standard deviation at 0.2 ppm (10 determinations) was 0.0022 and the relative error was ±0.78%. The interferences of many foreign ions are studied, concluding that the procedure proposed shows a high selectivity. The method has been applied satisfactorily to the determination of gold in ores, leads and other materials.