阻抑动力学光度法测定饮料中痕量柠檬酸的研究

Determination of trace citric acid in beverages by the inhibition spectrophotometric method

基于柠檬酸在硫酸介质中对铁（Ⅲ）催化过氧化氢氧化孔雀石绿的阻抑反应，建立了阻抑动力学光度法测定痕量柠檬酸的新方法。该方法的检出限为1．56×10^-7g／mL，线性范围为0-40μg／25mL，已应用于饮料样品中痕量柠檬酸的测定，加标回收率为98．5％-100．4％，相对标准偏差RSD〈5％，可满足一般饮料的测定要求。

Citric acid can inhibit the catalytic oxidation reaction of malachite green with hydrogen peroxide by Fe3＋ in H2SO4 solution. Therefore, a new inhibitory kinetic spectrophotometric method for determination of trace citric acid was established. The detection limit was 1.56×10^-7g/ml while the linear range was 0-40μg/25ml. The method was used to detect the trace citric acid in beverages. The recovery rate was 98.5%-100.4% while the relative standard deviation was less than 5%. The method meets the determination requirement for general beverages.