Development of an Eco-Friendly Spectrophotometric Method for Quantitative Determination of Phenol in Drinking Water

Abstract

A simple, rapid and eco-friendly spectrophotometric approach was devised and validated for the measurement of phenol at trace level in drinking water. The approach depends on the interaction of phenol with a chromogenic reagent under optimised alkaline conditions (pH 10.5) to generate a stable coloured complex with an absorption maximum at 510 nm. The Beer's law was obeyed in the concentration range of 15.0-400.0 µg/L with a molar absorptivity of 2.8 x 10 4 L mol-1 cm-1 and correlation value of 0.9994 . The detection limit was 4.0 μg/L and the quantification limit was 13.4 μg/L. The intra-day and inter-day precisions were 1.3–2.1% and 1.7–2.8%, respectively (relative standard deviation). The approach showed high selectivity in the presence of common inorganic ions (Cl^-, SO₄^2-, NO3^-, Ca²⁺, Mg²⁺) with tolerance ratios >500-fold and organic matter (10-fold). The procedure was applied to twelve drinking water samples from the distribution network and findings were in good agreement with those obtained by the standard 4-aminoantipyrine reference method with relative differences below 4%. The proposed method follows the principles of green analytical chemistry, since it uses aqueous reaction media, reducing the consumption of organic solvents and minimising waste generation, thus being suitable for routine monitoring of phenol in water quality laboratories, especially in resource-limited environments.