标准加入法(又称已知加入、标准增量或已知增量法)是应用离子选择电极分析测量中最常用的方法之一。本文就标准加入法的误差问题作一简要分析。设电极在样品溶液中的电势为(以阳离子为例,且设溶液离子强度、离子络合程度及液接界电势均保持不变):式中E’_0为常数电势,S为电极斜率(对1价离子25℃时为59.16毫伏),C_x为被测离子浓度。当加入浓度为C_s、体积为V_s的标准溶液时,电势值变为:式中V_x为样品溶液体积。从上述两式得到: 在与C_x有关的因素中,标准溶液浓度C_s的误差及体积V_x、V_s的测量误差可控制很小,主要的误差 Standard addition method (also known as known to join, the standard incremental or known incremental method) is the application of ion-selective electrode analysis and measurement of one of the most commonly used method. This article makes a brief analysis on the error of standard joining law. Assuming the potential of the electrode in the sample solution is (taking cation as an example, assuming that the ionic strength of the solution, the degree of ionic complexation and the potential of the liquid junction remain unchanged): where E’_0 is a constant potential and S is the slope of the electrode 59.16 mV for monovalent ions at 25 ° C), C_x is the measured ion concentration. When adding a standard solution of concentration C_s and volume V_s, the potential value becomes: where V_x is the sample solution volume. Obtained from the above two equations: Among the factors related to C_x, the error of the standard solution concentration C_s and the measurement error of the volumes V_x and V_s can be controlled very little. The main error