Situmorang M, Alexander P W, Hibbert D B
Department of Analytical Chemistry, University of New South Wales, Sydney, NSW 2052, Australia.
Talanta. 1999 Jul;49(3):639-49. doi: 10.1016/s0039-9140(99)00057-0.
Flow injection potentiometry (FIP) for the enzymatic determination of cholesterol is reported. The assay utilises a combination of three enzymes: cholesterol esterase (CE), cholesterol oxidase (COD) and peroxidase (POD). The method is developed by the use of a tungsten wire electrode as a sensor vs. Ag/AgCl in conjunction with a redox mediator ferrocyanide. CE converts esterified cholesterol to free cholesterol, which is then oxidised by COD with hydrogen peroxide as product. Ferrocyanide is converted to ferricyanide by hydrogen peroxide, catalysed by POD, and the tungsten electrode responds to the ratio of ferricyanide to ferrocyanide. Flow injection potentiometry gave well-defined peaks for cholesterol samples with a fast response (30 s). Linear calibration was obtained from 0.05 to 3.0 mM cholesterol, with a slope of 60.2 mV/decade change in cholesterol concentration, and detection limit 0.01 mM cholesterol (S/N=3). Repeatability was 3% (CV). Interferences from commonly found species were shown to be negligible. The sensor cell is simple to construct, and it was free from surface contamination problems over long periods of use. The application of the sensor for the determination of serum cholesterol was demonstrated.
报道了用于酶法测定胆固醇的流动注射电位分析法（FIP）。该测定法利用了三种酶的组合：胆固醇酯酶（CE）、胆固醇氧化酶（COD）和过氧化物酶（POD）。该方法是通过使用钨丝电极作为传感器与Ag/AgCl电极，并结合氧化还原介质亚铁氰化物而开发的。CE将酯化胆固醇转化为游离胆固醇，然后游离胆固醇被COD氧化，生成过氧化氢。在POD的催化下，过氧化氢将亚铁氰化物转化为铁氰化物，钨电极对铁氰化物与亚铁氰化物的比例作出响应。流动注射电位分析法对胆固醇样品给出了明确的峰，响应迅速（30秒）。在0.05至3.0 mM胆固醇范围内获得线性校准，胆固醇浓度每变化十倍，斜率为60.2 mV，检测限为0.01 mM胆固醇（S/N = 3）。重复性为3%（CV）。常见物质的干扰可忽略不计。传感器池易于构建，并且在长期使用中不存在表面污染问题。展示了该传感器在血清胆固醇测定中的应用。
