欧盟OMCL仪器确认附件9：pH计（中英文）

201511 PA/PH/OMCL (13) 86 3R 欧盟OMCL仪器确认附件9：pH计（中英文）  

OMCL Network of the Council of Europe

QUALITY MANAGEMENT DOCUMENT

PA/PH/OMCL (13) 86 3R

QUALIFICATION OF EQUIPMENT

ANNEX 9: CALIBRATION/QUALIFICATION OF PH-METERS

OMCL质量管理文件

PA/PH/OMCL (13) 86 3R

仪器验证

附件9：pH计校正/确认

Full document title and reference	Qualification of Equipment Annex 9: Calibration/Qualification of pH Meters PA/PH/OMCL (13) 86 3R
文件全名和索引号	设备确认 附件9：pH计校正/确认 PA/PH/OMCL (13) 86 3R
Document type	Guideline
文件类型	指南
Legislative basis
法规依据
Date of first adoption	23 October 2015
首次采纳日期	2015年10月23日
Date of original entry into force	1st November 2015
首次生效日期	2015年11月1日
Date of entry into force of revised document
修订后文件生效日期
Previous titles/other references / last valid version
旧文件题目/其它索引号/最后有效版本
Custodian Organisation	The present document was elaborated by the OMCL Network /EDQM of the Council of Europe
监管机构	现行文件由OMCL网络/EDQM起草
Concerned Network	GEON
相关网络	GEON

ANNEX 9 OF THE OMCL NETWORK GUIDELINE “QUALIFICATION OF EQUIPMENT” CALIBRATION / QUALIFICATION OF pH METERS

OMCL网络指南“仪器验证”之

附件9：pH计校正/确认

1. INTRODUCTION 概述

This document is the 9th Annex to the core document “Qualification of Equipment”, which taken together should be used when planning, performing and documenting the qualification process of pH meters. The core document contains the introduction and general forms for Level I and II of qualification, which are common to all types of instruments.

本文件是核心文件“仪器确认”的第9个附件。在规划、实施和记录pH计的确认过程时应将本文件与核心文件一起使用。核心文件包括第I级和第II级确认的概述和通用表格，所有类型的仪器都是通用的。

Annex 9 contains instrument-related recommendations on parameters to be checked at Level III and IV of qualification and the corresponding typical acceptance limits, as well as practical examples on the methodology that can be used to carry out these checks.

附件9包括与仪器相关第III级和第IV级确认所需检查的参数的建议，以及对应的一般可接受限度，还有可以用来实施这些检查的方法学实际案例。

2. AIM AND SCOPE OF THE GUIDELINE 本指南的目标和范围

This guideline describes the requirements for pH meters used for determination of pH in aqueous solutions. If measurements are made of test solutions of a non-aqueous or partially non-aqueous character, suspensions or emulsions, on a system calibrated as described above, the pH reading can only be considered to be an approximation of the true value (apparent pH). Appropriate electrodes should be used for such types of measurement.

本指南描述了用于测定水溶液pH值的pH计的要求。如果所检测的是非水性溶液，或者是部分非分水溶性、混悬液或乳液，采用上述方法校正的系统进行检测，所获得的pH读数只能用为真值（表征pH值）的近似值。此类检测需要使用适当的电极。

The general principles of pH measurement together with apparatus and methods are provided in Ph.Eur. Chapter 2.2.3. ‘Potentiometric determination of pH‘.

pH测量和仪器及方法的通则在欧洲药典第2.2.3章“电位法测定pH值”中给出。

3. CONSIDERATIONS FOR LEVEL I AND II OF EQUIPMENT QUALIFICATION 第I级和第II级仪器确认中的考虑

At level I of the qualification of a pH meter (selection of instruments and suppliers) it is recommended to select a manufacturer of pH meters that can satisfy the needs of the laboratory and works under ISO 9001 certification. At level II of the qualification of a pH meter (installation and release for use) it is recommended to check all requirements set during the selection of the instrument, and calibration should be performed before putting into service by an accredited external service supplier, or internally by appropriately qualified personnel, using certified reference buffers according to an approved procedure.

在pH计第I级确认（仪器和供应商选择）中，建议选择可以满足化验室需求的pH计生产商，并且在ISO9001认证体系下运行。在pH计第II级确认（安装和放行使用）中，建议检查所有仪器选择中设定的要求，在由经过认证的外部服务商提供服务，或者由内部具备适当资质的人员接手管理之前要进行校正。校正要使用经过认证的标准缓冲液根据批准的程序进行。

4. MANAGEMENT OF ELECTRODES 电极管理

Before measurement, the electrode(s) is (are) checked visually. The electrodes should be appropriately stored according to recommendations of the manufacturer (e.g. in a storage electrolyte). Refillable electrodes should be checked to ensure that the level of the inner electrolyte is satisfactory and no bubbles are present in the glass bulb. The diaphragm of the reference electrode should also be checked. Before first use, or if it has been stored out of electrolyte, it is usually necessary to condition the electrode according to the recommendation of the manufacturer.

在开始测量之前，要对电极进行目视检查。电极应根据生产商的建议适当存贮（例如，放在电解液中）。可以重装的电极应进行检查，以保证内部电解液 液面高满足要求，在玻璃泡里没有气泡。参比电极的隔层也要进行检查，。在首次使用之前，或者如果已经脱离电解液存贮了很久，通常需要根据生产商的建议调整 电极。

If the stabilisation of pH is too slow (long response time) or if there are difficulties in calibration, the electrode will probably need to be cleaned or replaced. Cleaning procedure depends on the type of sample used as prescribed in the manual. Regular cleaning is recommended.

如果pH值稳定过程太慢（响应时间太长），或者难以校正，则电极可能需要进行清洁或替换。清洁程序取决于手册中所述的受测样品类型。建议定期进行清洁。

5. CALIBRATION AND MEASUREMENT CONDITIONS 校正和测量调整

The calibration consists of the determination of the slope and the offset of the measuring system.

校正包括测定斜率和测量系统补偿。

Unless otherwise prescribed in the method, all measurements are performed at the same temperature (± 2.5 °C) usually between 20 and 25 °C. The variation of pH with respect to temperature of a number of reference buffer solutions used for calibration is given in Ph. Eur. Chapter 2.2.3.. For the temperature correction, when necessary, follow the manufacturer’s instructions. The apparatus is usually calibrated with two buffer solutions which should be chosen so that the expected pH value of the test sample lies in between the pH values of the buffer solutions. The range should be at least 2 pH units. The pH of a third buffer solution of intermediate pH read off on the scale must not differ by more than 0.05 pH units from the value corresponding to this solution. If the deviation is greater than +/-0.05 units, this may be because the range of the buffers chosen was too broad and recalibration with a different system of buffers may be necessary.

除方法中另有要求外，所有测量均应在相同温度（± 2.5 °C）下进行，通常是20 到 25 °C。在欧洲药典第2.2.3章中给出了校正所用的一系列标准缓冲液的pH值在不同温度下的波动值。必要时，要根据生产商的指导进行温度修正。仪器通常采用2个缓冲液进行校正，受测样品的预计pH值应该落在这2个缓冲液pH值之间。2个缓冲液pH值所覆盖范围至少为2个pH单位。用于中间pH值读数的第3个缓冲液的pH值必须与受测样品的读数值相关不超过0.05。如果偏差大于+/—0.05单位，则可能是因为所选的缓冲液的范围太宽，可能需要采用另一个缓冲液系统重新校正。

Alternatively, a multi-point calibration may be performed to cover a wider pH-range. In that case it may be necessary to use more than one buffer solution for the verification depending on the expected pH values of the test samples.

也可以采用多点校正来覆盖更宽的pH范围。在这种情况下，根据受测样品的预期pH值，可能有必要使用多于1种缓冲液来核对。

The reference buffer solutions should preferably be certified reference materials. Otherwise, buffer solutions may be prepared as given in Ph. Eur. Chapter 2.2.3. These should be traceable to primary standards.

参照缓冲液最好是经过认证的对照材料。也可以根据EP第2.2.3章中给出的方法来配制缓冲液。这时应能追溯到基准对照物。

Immerse the electrodes in the solution to be examined and take the reading in the same conditions as for the buffer solutions.

将电极浸在被测溶液中，在和缓冲液相同的条件下读数。

Regular calibrations have to be performed as given in paragraph 6.

必须根据第6段中给出的方法进行日常校正。

All solutions to be examined and the reference buffer solutions must be prepared using carbon dioxide-free water R.

所有溶液都要检查，标准缓冲液必须使用无二氧化碳的试剂用水来配制。

STORAGE of buffer solutions 缓冲溶液的存贮

Store buffer solutions in suitable chemically resistant, tight containers, such as type I glass bottles or plastic containers suitable for aqueous solutions. Buffer solutions made in house- should not be kept for more than 3 months at room temperature. For commercially available buffer solutions, manufacturers‘ recommendations should be taken into account.

将缓冲液存贮在适当的耐化学腐蚀的密闭容器中，例如I类玻璃瓶，或适合水性溶液的塑料容器。公司内部配制的缓冲液在室温下保存时间不应超过3个月。市售缓冲液，要考虑生产商的建议。

6. LEVEL III AND IV QUALIFICATION OF PH METERS pH计的第III级和第IV级确认

Most commercial pH meters offer a “self test” or “start-up test” where e.g. slope (and asymmetry potential) are tested and compared to the manufacturer`s specifications.

大多商用pH计提供“自测”或“开始测试”用于例如斜率（以及非对称电位）测定，并与生产商的标准对比。

Level III 第III级

Test to be performed	Minimum frequency	Typical tolerance limit	Who
要实施的测试	最低频次	一般允差限度	谁做
Calibration or verification of thermometer	every two years	Manufacturer’s specification or OMCL	external service supplier or OMCL
温度计校正或核对	第2年	生产商标准或OMCL标准	外部服务商或OMCL

Level IV: Calibration/verification 第IV级：校正/核对

Parameter to be checked	Typical frequency	Typical tolerance limit	Who
要检查的参数	一般频次	一般允差限度	谁做
Slope 斜率	Each day of use of before each series of measurements 每天不同测量范围使用前	95.0 to 105.0%	OMCL
Offset (pH-asymmetry) 补偿（pH非对称电位）		+/-30mV (offset of manufacturer+/-0.5pH units at defined temperature) +/-30mV（在指定的温度下生产商补偿+/-0.5pH单位）
Reference buffer solution 对照缓冲液		+/-0.05 pH units

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