Solid-phase spectrophotometric determination of hydrogen peroxide

Abstract

A combined solid-phase spectrophotometric iodometric method for the determination of hydrogen peroxide using a methacrylate polymer was proposed. The method was based on the oxidation reaction of iodide ion with hydrogen peroxide in the hydrochloric acid with the release of free iodine. The iodine was extracted from the solution by a polymethacrylate matrix, and its concentration was measured at the absorbance of 365 nm. The amount of iodine extracted by the polymethacrylate matrix was proportional to the concentration of hydrogen peroxide in the solution. The effect of interfering ions was also investigated. The optimal phase contact time was 5 minutes. The effect of adding the hydrochloric acid to the analyzed solution on the analytical signal of the polymethacrylate matrix after its contact with hydrogen peroxide solution was studied. It was shown that the maximum signal was obtained in the range of acid concentrations in the solution of (3–5)∙10 –3 M. The optimal concentration of potassium iodide in the analyzed solution for the redox reaction was 0.06%. At this concentration, the widest range of detectable concentrations was achieved with the smallest limit of detection for hydrogen peroxide. The developed procedure ensured the determination in the range of (15–130)∙10 -5 % of hydrogen peroxide with the detection limit of 5 × 10 -5 %. The results of the determination of hydrogen peroxide were given for the proposed method in samples of disinfectants and bleaching agents. The proposed method for hydrogen peroxide determination is more preferable in comparison to the iodometric method [1] as it provides the increased sensitivity, simplicity and rapid analysis, the absence of losses of released iodine due to its solid-phase extraction into the methacrylate polymer and can be conducted using the standard spectrophotometric equipment.