摘要
在H2SO4溶液中,柠檬酸对Fe(Ⅲ)催化过氧化氢氧化中性红的褪色反应具有很强抑制作用,十六烷基三甲基溴化铵对此上述指示反应有增敏作用,从而提出了一种阻抑动力学光度法测定汽水中痕量柠檬酸的新方法。本文研究了吸收光谱、试剂用量、干扰离子等因素的影响,测定了动力学参数。在最佳实验条件下,阻抑反应与非阻抑反应体系在520 nm处的吸光度差值与柠檬酸的质量浓度在0.8～200μg.L-1范围内呈良好线性关系,检测限为2.51×10-6g.L-1。在表面活性剂存在下,灵敏度提高6倍。此法用于汽水中柠檬酸的测定,结果满意。
Citric acid can inhibit the discoloration of the catalytic oxidation reaction of neutral red with hydrogen peroxide by Fe3 ＋ in the presence of H2SO4 solution and using cationic surfactant of cetyhrimethyl ammonium bromide as an sensitizer. A new inhibitory catalytic kinetic spectrophotometric method for the determination of trace amount of citric acid has been developed. The effects of the factors such as absorption spectra, acidity, concentrations of reagent, influence of coexisting ions on the reaction are discussed and the kinetic conditions are studied. Under the optimum conditions, good linear relationship is obtained between absorbance differeee （△ A ） of the inhibited system and non-inhibited system at 520 nm and the concentration of citric acid in the range of 0.8 - 200μg/L,the detection limit is 2.51 ×10-6g·L^-1, The sensitivity is increased by 6 times than in the absence of the surfactant. The method can be used for the determination of citric acid in aerated water with satisfactory result.
基金
吉林省教育厅项目(吉教科合字[2010]第382号)
长春师范大学自然科学基金(长师院自科合字[2010]第023号)
