表面活性剂增敏苏丹红B褪色反应光度法测定亚硝酸根

Determination of nitrite by catalytic kinetic spectrophotometry of Sudan red B with surfactant sensitizer

构建了一种测定亚硝酸根的催化动力学光度法.基于稀硫酸介质中,阳离子表面活性剂十六烷基三甲基溴化铵对亚硝酸根催化溴酸钾氧化苏丹红B褪色反应的增敏作用,建立了测定亚硝酸根的表面活性剂增敏催化动力学光度法.通过实验条件的优化,在30℃,反应时间从反应开始到3 min为止,495 nm处用分光光度法测定反应体系吸光度的减少值,从而测定其反应速率.实验结果表明,加入十六烷基三甲基溴化铵后,非催化体系吸光度A0和催化体系吸光度A的差值△A（=A0-A）增大约1倍.研究了催化反应的动力学条件,测定了反应的表观速率常数k为3.07×10-4s-1和表观活化能Ea为57.44 kJ/mol.体系△A值与亚硝酸根的浓度在0.01～0.2mg/L范围内呈良好的线性关系,检测限为5.0 μg/L.用于泡椒鲜竹食品中亚硝酸根的测定,结果满意.

A catalytic kinetic spectrophotometric method for the determination of nitrite with surfactant sensitizer was developed.The method was based on the catalysis of nitrite to the color faded reaction of Sudan red B by potassium bromate in the medium of dilute H2SO4,and cetyl trimethyl ammonium bromide （CTMAB） can be used as a sensitizer of the reaction.The experimental conditions were optimized.The reaction rate was followed based on spectrophotometric method by measuring the decrease of the system in absorbance at 495 nm and 30 ℃ with a fixed time of 3 min from initiation of the reaction.When adding CTMAB to the system,the variation （△A） in absorbance increased one time approximately between non-catalytic system and catalytic system.The kinetic conditions were studied,and the apparent reaction rate constant k and the apparent activation energy Ea were calculated to be 3.07× 10-4 s-1 and 57.44 kJ/mol,respectively.The values of △A were linear with the concentrations of nitrite in range of 0.01～0.2 mg/L with the detection limit of 5.0 μg/L.This method was applied to the determination of nitrite in food samples with satisfactory results.