GB6851-2008
pH primary reagent - General rules for certification
pH基准试剂 定值通则
GB 6851-2008 is a current mandatory Chinese national standard for pH primary reagent - General rules for certification. It appears in the Electronics compliance cluster with a testing methods focus and has an implementation date of Jun 1, 2009.
Applicability depends on product scope, certification route, competent authority notices and transition rules. Requst for the translation or verify source before using this record in a compliance decision.
Compliance overview
Scope and applicability
This standard applies to the certification and value determination of pH primary reagents and the preparation of pH standard buffer solutions at 25°C. It is specifically designed for chemical reagent manufacturers and metrology laboratories involved in the calibration of high-precision pH meters. It is not applicable to general industrial pH buffering agents not used for certified instrument calibration.
Technical requirements
GB 6851-2008 establishes the general rules for determining the pH value of primary reagents using a double hydrogen electrode cell with liquid junction. The standard mandates specific preparation methods for various buffer solutions, including potassium hydrogen phthalate, potassium dihydrogen phosphate, and sodium tetraborate mixtures. A key requirement is the strict control of experimental conditions, including the use of high-purity hydrogen gas and Grade 2 laboratory water as specified in GB/T 6682. Manufacturers must ensure that the residual liquid junction potential is minimized to an acceptable threshold to maintain measurement integrity. Furthermore, the standard outlines the requirements for the expanded uncertainty of the pH standard buffer solutions. It defines the acceptable limits of precision for the final certified pH values, ensuring traceability to national metrological standards.
Testing methods
The primary testing method involves a comparative measurement using a double hydrogen electrode cell with a liquid junction. The procedure requires monitoring the cell's electromotive force (EMF) at a strictly controlled temperature of 25.0°C ± 0.1°C until equilibrium is reached. Additionally, the standard details the preparation and treatment of platinum/palladium hydrogen electrodes and specific salt bridges, as outlined in the normative appendices.
FAQs
What products are regulated under GB 6851-2008?
This standard regulates the certification of pH primary reagents and the preparation of pH standard buffer solutions used for the calibration of pH meters in China.
Are there any updates from the previous version of GB 6851-2008?
The 2008 version updated terminology, such as changing "primary pH reagent" to "pH primary reference material," and introduced the calculation of expanded uncertainty for pH standard buffer solutions, replacing the older GB 6851-1986.
How does GB 6851-2008 differ from ISO standards?
GB 6851-2008 is specifically tailored for China's national metrology framework, defining strict localized procedures and mandatory apparatus setups for pH value certification at 25°C, whereas ISO standards generally provide broader international guidelines.
The summary above provides a high-level overview of GB 6851-2008. To ensure complete compliance for your products entering the Chinese market, a precise and professional translation of the full technical specifications is essential. Purchase our high-quality English translation of GB 6851-2008 today to access all detailed parameters, tables, and testing procedures.
Applicability hints
- Type
- Method
- CCS
- G60
- ICS
- 71.040.30
- Competent department
- Ministry of Industry and Information Technology
- Technical committee
- Ministry of Industry and Information Technology
Relationships
Replaces:GB 6851-1986