A Method for Nonextractive Simultaneous Determination of Thallium (III) and Gallium (III) in Environmental and Standard Samples with 2‐(5‐Bromo‐2‐pyridylazo)‐5‐diethylaminophenol in Cationic Micellar Medium

Abstract

A new sensitive and selective derivative spectrophotometric procedure is developed for trace‐level determination of Tl³⁺ in the range of 6.80 × 10⁻² to 3.80 µg mL⁻¹; molar absorption coefficient and detection limit of a 1:1 complex with 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol in the presence of cetylpyridinium chloride are 5.25 × 10⁴ L mol⁻¹ cm⁻¹ and 4.20 × 10⁻² ng mL⁻¹, respectively. The developed method, by using the measurement of the derivative amplitude of the analyte (Tl³⁺) at the zero crossover point of the interfering metal ion (Ga³⁺), is applied for the determination of Tl³⁺ in the presence of Ga³⁺, and vice versa for Ga³⁺ ions. The determination range of Tl³⁺ and Ga³⁺ in the presence of each other is 0.10–2.46 µg mL⁻¹ and 0.04–1.05 µg mL⁻¹, respectively; the relative standard deviation for sample containing 1.23 µg mL⁻¹ Tl³⁺ and 0.42 µg mL⁻¹ Ga³⁺ is 1.43 and 1.65%, respectively. The proposed procedure is successfully applied for simultaneous determination of the two metal ions in the environmental samples, standard reference materials, and synthetic binary mixtures.

Keywords:

• 5‐Br‐PADAP
• Zero crossover point
• Derivative amplitude
• Peak height
• Trough depth

Acknowledgments

The authors gratefully acknowledge the financial assistance provided by UGC (JRF) to SR and to Prof. H. B. Singh for suggestions.