Dietzler D N, Leckie M P, Hoelting C R, Porter S E, Smith C H, Tieber V L
Clin Chim Acta. 1983 Jan 24;127(2):239-50. doi: 10.1016/s0009-8981(83)80008-4.
The logit-log and four-parameter logistic procedures when appropriate for calculation of enzyme-multiplied immunoassay (EMIT) data have the advantage that they can be applied regardless of the kinetic analyzer or reaction conditions. To use these procedures correctly one must determine the change in absorbance at an infinite drug concentration (delta A infinity). The marked variation of delta A infinity with equipment and reaction conditions and the difficulty in determining this value have hindered broad use of these otherwise universally applicable procedures. We have evaluated two simple methods for determining delta A infinity, both based on its equivalence to delta A in the absence of specific antibody: (1) cross-kit reaction using antibody/substrate and enzyme-drug reagents from kits for different drugs, and (2) substitution of an antibody-free substrate reagent with composition based on direct analysis. The cross-kit procedure was tested with EMIT assays for phenobarbital, primidone, phenytoin, carbamazepine, ethosuximide, and theophylline. In some cases an unexpected type of cross-reaction occurred, giving an erroneously low value for delta A infinity. The antibody-free substrate reagent always permitted accurate determination of delta A infinity.
当适用于酶放大免疫分析技术（EMIT）数据计算时，对数-对数法和四参数逻辑法具有这样的优势：无论使用何种动力学分析仪或反应条件，它们均可适用。为正确使用这些方法，必须确定无限药物浓度下的吸光度变化值（δA∞）。由于δA∞随设备和反应条件的显著变化以及确定该值的难度，阻碍了这些原本普遍适用的方法的广泛应用。我们评估了两种确定δA∞的简单方法，这两种方法均基于其在不存在特异性抗体时与δA的等效性：（1）使用来自不同药物试剂盒的抗体/底物和酶-药物试剂进行试剂盒间交叉反应，以及（2）基于直接分析用无抗体底物试剂进行替代。用EMIT分析法对苯巴比妥、扑米酮、苯妥英、卡马西平、乙琥胺和茶碱进行了试剂盒间交叉反应程序测试。在某些情况下，会出现意外的交叉反应类型，导致δA∞值错误地偏低。无抗体底物试剂总能准确测定δA∞。
