Wilson J F, Williams J, Tsanaclis L M, Tedstone J E, Richens A
Department of Pharmacology and Therapeutics, University of Wales College of Medicine, Cardiff.
Ther Drug Monit. 1988;10(4):438-45. doi: 10.1097/00007691-198804000-00011.
The accuracy and precision of assay techniques used to measure theophylline concentrations in human serum were compared using data from 96 samples from the Heathcontrol external quality assurance scheme. Abbott TDX had the highest precision, with a mean coefficient of variation (CV) of measurements of 6.4%, and Ames Fluorostat was most accurate, with a mean bias of +0.1%. Differences between the better techniques, however, were not significant. The Beckman ICS assay gave the lowest precision (CV 9.3%) and, in addition, produced the highest proportion (7.5%) of rejected observations greater than 3 standard deviations from the sample mean. The least accurate method was radioimmunoassay, with a -9.9% bias. Measurements from two samples spiked with paraxanthine demonstrated that 76% of laboratories using high-pressure liquid chromatography (HPLC) were unable to distinguish between paraxanthine and theophylline. The +4% bias observed at low concentrations and the high variability (CV 8.3%) of measurements made by HPLC were thus attributed to interference by paraxanthine present in the sample matrix. Discriminant analysis of a range of HPLC column and mobile phase parameters indicated that separation of theophylline and paraxanthine was achieved by the use of lower flow rates with mobile phases of solvent mixtures with lower proton donator selectivity.
利用来自Heathcontrol外部质量保证计划的96份样本数据，对用于测量人血清中茶碱浓度的分析技术的准确性和精密度进行了比较。雅培TDX的精密度最高，测量的平均变异系数（CV）为6.4%，而艾姆斯荧光计最准确，平均偏差为+0.1%。然而，较好技术之间的差异并不显著。贝克曼ICS分析的精密度最低（CV为9.3%），此外，被拒绝的观测值（大于样本均值3个标准差）的比例最高（7.5%）。最不准确的方法是放射免疫分析，偏差为-9.9%。对两个添加了对黄嘌呤的样本的测量表明，76%使用高压液相色谱（HPLC）的实验室无法区分对黄嘌呤和茶碱。因此，在低浓度下观察到的+4%偏差以及HPLC测量的高变异性（CV为8.3%）归因于样本基质中存在的对黄嘌呤的干扰。对一系列HPLC柱和流动相参数的判别分析表明，通过使用较低流速以及具有较低质子供体选择性的溶剂混合物流动相，可以实现茶碱和对黄嘌呤的分离。
