测定食品中痕量甲醛的动力学光度法

Kinetic Spectrophotometric Determination of Trace Formaldehyde in Foodstuff Based on Oxidation Discoloration of Acid Chrome Blue K with Potassium Bromate

通过基于0.04mol/L的硫酸介质中痕量甲醛催化溴酸钾氧化酸性铬蓝K(ACBK)的褪色反应,建立了测定痕量甲醛的动力学光度法。方法的检出限为0.93μg/L,线性范围为0.0～0.40μg/mL。讨论了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响,确定了该体系反应的最佳条件,并测定了一些动力学参数,催化反应的表观活化能为69.47kJ/mol。在25mL溶液中,测定5.0μg甲醛的相对标准偏差为1.9%(n=11)。方法可用于测定水发牛百叶和虾仁样品中的甲醛,相对标准偏差为1.1%～2.3%,标准加入回收率为98.7%～101.4%。

Based on the catalytic effect of trace amount formaldehyde on oxidation of acid chrome blue K（ACBK） by potassium bromate in 0.04 mol/L sulphuric acid solution,a new kinetic spectrophotometric method for the determination of trace amount formaldehyde has been developed.The detection limit is 0.93 μg/L and the linear range of determination is 0.0-0.40 μg/mL for formaldehyde.The relative standard deviation for the determination of formaldehyde at the concentration of 5.0 μg/25 mL is calculated to be 1.9 %（n =11）.The factors such as acidity,concentrations of reactants,reactive time,temperature,influence of coexisting ions on the reaction and the optimum reaction conditions of the reaction and some kinetic parameters are determined;the apparent activation energy of the reaction is 69.47 kJ/mol.The method has been applied to the determination of formaldehyde in runnet and peeled shrimp samples with the relative standard deviation of 1.1 %-2.3 % and the recovery of 98.7 %-101.4 %.