Selective Spectrophotometric Investigation and Determination with Some Thiazolylazo Compounds, of Palladium(II), or of Tartaric Acid in the Presence of Niobium(V)

Abstract

Spectrophotometric investigation of palladium(II) or of tartaric acid in presence of niobium(V) were conducted using their colour reactions with 5‐(benzothiazolyl‐azo)2,5‐naphthalenediol (I), 1‐(2‐benzothiazolylazo)2‐hydroxy‐3‐naphthoic acid (II) and 5‐(2‐benzothiazolylazo)8‐hydroxyquinoline (III) in acidic medium, or weak acidic medium. The stoichiometric ratios and stability constants of the formed complexes were determined. The calibration graphs were linear in the range of 0.02–1.35, 0.02–1.20, and 0.02–1.10 µg mL⁻¹ of Pd²⁺ with apparent molar absorptivities of 6.15 × 10⁴, 7.27 × 10⁴ and 5.80 × 10⁴, L mol⁻¹ cm⁻¹ using I, II, and III, respectively, at λ_max 638, 677, and 656 nm.

On the other hand, calibration graphs for tartaric acid in the presence of Nb⁵⁺ were linear in the 0.01–1.60, 0.01–1.7, and 0.01–1.45 µg mL⁻¹ range with ϵ of 1.27 × 10⁵, 1.13 × 10⁵, and 1.45 × 10⁵ L mol⁻¹ cm⁻¹ at 692, 649, and 661 nm, respectively. Sandell sensitivity, detection, and quantification limits were also calculated. The proposed methods were selective and sensitive in comparison with other methods and the effect of foreign ions Cu²⁺, Ni²⁺, and Fe²⁺ was negligible for the assay of Pd²⁺.

Keywords:

• Thiazolylazo compounds
• Palladium and tartaric acid determinations
• Spectrophotometry