欧洲药典EP8.0 滴位测定 中文翻译

2.2.20. POTENTIOMETRIC TITRATION 电位滴定

In a potentiometric titration the end-point of the titration is

determined by following the variation of the potential difference between 2

electrodes (either one indicator electrode and one reference electrode or 2

indicator electrodes) immersed in the solution to be examined as a function of

the quantity of titrant added.

在一个电位滴定中，滴定终点判定是依据浸入被测液中两支电极（或者是一支指示电极一支参比电极，或者是两支指示电极）之间的电位差，对应加入滴定液的数量。

The potential is usually measured at zero or practically zero

current.

电位一般在零点测量，或在零点电流。

Apparatus. The apparatus used (a simple potentiometer or electronic

device) comprises a voltmeter allowing reading to the nearest millivolt.

仪器：所用仪器（一个简单的电位计或电极装置）包括一个可以准确读至毫伏的电位计。

The indicator electrode to be used depends on the substance to be

determined and may be a glass or metal electrode (for example, platinum, gold,

silver or mercury). The reference electrod is generally a calomel or a

silver-silver chloride electrode.

所用的指示电极依赖于所检测的物质，可以是玻璃电极或金属电极（例如，铂电极、金电极、银或水银电极）。参比电极一般是甘汞电极或银-氯化银电极。

For acid-base titrations and unless otherwise prescribed, a

glass-calomel or glass-silver-silver chloride electrode combination is used.

对于酸碱电极，如未另加说明，一般使用玻璃甘汞电极或玻璃-银-氯化银复合电极。

Method. the solvent mixture is neutralized, if necessary, before

dissolution of the substance to be examined. Plot a graph of the variation of

potential difference as a function of the quantity of the titrant added, continuing

the addition of the titrant beyond the presumed equivalence point. The end-point corresponds to a sharp variation of he potential difference.

方法：如有必要，在被测样品溶解前，中和溶液混合物使呈中性。以电位变化和滴定液加入量作图，继续滴加至预定的平衡点。终点对应电位变化突跃点。