European Journal of Biomedical and Pharmaceutical Sciences

VALIDATED UV–VISIBLE SPECTROPHOTOMETRIC DETERMINATION OF COPPER(II), NICKEL(II) AND COBALT(II) USING A HYDROXYTRIAZENE REAGENT

S. Y. Birpan*, Dr. Pranjali Shinde

ABSTRACT

A sensitive, accurate and validated UV–Visible spectrophotometric method was developed for the determination of Cu(II), Ni(II) and Co(II) using a hydroxytriazene chromogenic reagent. The analytical procedure was optimized by a classical univariate approach, in which the effects of individual experimental variables were systematically investigated. The metal ions reacted with the hydroxytriazene reagent under controlled conditions in acetate–acetic acid buffer at pH 6.5, producing coloured metal–ligand complexes suitable for spectrophotometric measurement. The optimum reaction conditions included 3.0 mL of 0.1% hydroxytriazene reagent and a standing time of 15 min. The proposed method exhibited good linearity over the concentration ranges of 0.2–1.6 µg mL⁻¹ for Cu(II) and Ni(II), and 0.3–1.8 µg mL⁻¹ for Co(II), with correlation coefficients of 0.9998, 0.9997 and 0.9995, respectively. The molar absorptivity values were found to be 1.86 × 10⁴, 1.42 × 10⁴ and 1.65 × 10⁴ L mol⁻¹ cm⁻¹ for Cu(II), Ni(II) and Co(II), respectively. The limits of detection were 0.018, 0.024 and 0.021 µg mL⁻¹, while the corresponding limits of quantification were 0.054, 0.072 and 0.063 µg mL⁻¹. Accuracy studies by the standard-addition method gave recoveries of 99.6–100.5% with relative standard deviations below 1%. Intra-day and inter-day precision studies showed RSD values below 1.5%. The method also demonstrated satisfactory robustness against small deliberate variations in pH, reagent volume, wavelength and standing time, while ruggedness studies showed good agreement between different analysts and instruments. The method was successfully applied to the determination of Cu(II), Ni(II) and Co(II) in water, industrial effluent, pharmaceutical and alloy samples. The proposed hydroxytriazene-based spectrophotometric procedure provides a simple, sensitive, precise and reliable analytical approach for the determination of these metal ions using conventional UV–Visible spectrophotometric instrumentation.

Keywords: Hydroxytriazene; Cu(II); Ni(II); Co(II); UV–Visible spectrophotometry; Metal–ligand complex; Simultaneous determination; Method validation; Trace metal analysis.