Enzyme Catalytic Chromogenic Method for Determination of Calcium Peroxide in Wheat Flour
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Abstract:
As calcium peroxide can generate hydrogen peroxide in an acidic medium, visual colorimetry for rapid qualitative analysis and spectrophotometry for quantitative analysis of calcium peroxide in wheat flour were established based on the principle that hydrogen peroxide can cause rapid oxidation and chromogenesis in quaternary amine [4,4′-(dimethyl amine)diphenyl methane] by using horseradish peroxidase (HPR) as the catalyst with KI as the sensitization agent. In this study, the experimental conditions for detecting calcium peroxide were optimized, and the experimental factors influencing chromogenesis, including the HPR content, KI content, quaternary amine content, pH, reaction temperature, and reaction time, were investigated. The results showed that under the optimum conditions, the color of the complex gradually deepened with increasing calcium peroxide content. Based on the relationship between the color gradients and concentration of calcium peroxide, a standard color card was created for visual colorimetric determination. Beer’s law was obeyed when the concentration range of calcium peroxide was within 0~9 mg/L. The linear regression equation was as follows: ΔA = 0.0052 + 0.107C, with a correlation coefficient of 0.9994. The recovery rate for spiked standards was within 96.3%–101.7%, and the relative standard deviation was 1.74%~3.15%. The range of calcium peroxide content was rapidly determined by visual colorimetry and its detection limit was 1.64 × 10-2 mg/L.
