Characterization of Three New Phosphonic (Arsonic) Acid Type Thiazolylazo Reagents and Application to Spectrophotometric Determination of Microamounts of Palladium

✍ Scribed by F.L. Zhang; B.C. Wu; H.C. Liu; C. Wu

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 304 KB
• Volume: 48
• Category: Article
• ISSN: 0026-265X
• DOI: 10.1006/mchj.1993.1077

✦ Synopsis

Three new thiazolylazo chromogenic reagents of phosphonic and arsonic acid types, namely 2-(2-benzothiazolylazo)-5-sulfomethylamino-4-tolylphosphonic acid (BTASTP), 2-(2-benzothiazolylazo)-5-sulfomethylamino-4-chlorobenzenephosphonic acid (BTASCP), and 2-(2-benzothiazolylazo)-5-sulfomethylamino-4-tolylarsonic acid (BTASTA), are described in this paper. Their syntheses and spectrophotometric behaviors have been thoroughly studied. They react with palladium(II) in relatively strong nitric acid medium containing appropriate amounts of dimethylformamide or ethanol to form intensely blue complexes with high sensitivity, selectivity, and stability. The composition ratios of (\mathrm{Pd}) (II) to these reagents are found to be (1: 1) and their absorption maxima are at 690,688 , and (695 \mathrm{~nm}) with apparent molar absorptivities of (8.3 \times 10^{4}, 5.85 \times 10^{4}), and (6.08 \times 10^{4}) liter (\cdot \mathrm{mol}^{-1} \cdot \mathrm{cm}^{-1}), respectively. Beer's law is obeyed up to 36,36 , and (37 \mu \mathrm{g} / 25 \mathrm{ml}), respectively. Relatively large amounts of coexisting elements including noble metals can be tolerated. The proposed method has been applied to the determination of palladium in (\mathrm{Cu}-\mathrm{Ni}) alloy, residue chloride of noble metals, and sulfur bearing concentrated ore of noble metals with satisfactory results. 1993 Academic Press. Inc.