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GB/T 13531.1-2008 English PDF (GBT13531.1-2008)

GB/T 13531.1-2008 English PDF (GBT13531.1-2008)

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GB/T 13531.1-2008: General methods on determination of cosmetics -- Determination of pH
GB/T 13531.1-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 71.100.70
Y 42
Replacing GB/T 13531.1-2000
General Methods on Determination of Cosmetics -
Determination of pH
ISSUED ON: DECEMBER 28, 2008
IMPLEMENTED ON: JUNE 1, 2009
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative References ... 4 
3 Principle ... 4 
4 Reagents ... 4 
5 Instruments ... 4 
6 Analytical Procedures ... 5 
7 Expression of Analytical Result ... 6 
8 Precision ... 6 
General Methods on Determination of Cosmetics -
Determination of pH
1 Scope
This Part of GB/T 13531 specifies the methods on the determination of pH value of
cosmetics.
This Part is applicable to the determination of pH value of cosmetics.
2 Normative References
Through the reference in this Part of GB/T 13531, the clauses of the following
documents become clauses of this Part. In terms of references with a specified date,
all the subsequent modification sheets (excluding the corrected content) or revised
versions are not applicable to this Part. However, the various parties that reach an
agreement in accordance with this Part are encouraged to explore the possibility of
adopting the latest version of these documents. In terms of references without a
specified date, the latest version is applicable to this Part.
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods
(GB/T 6682-2008, ISO 3696:1987, MOD)
3 Principle
Determine the potential difference between the glass electrode and the reference
electrode entering the cosmetics.
4 Reagents
4.1 Laboratory water shall adopt Grade-3 water specified in GB/T 6682; the electrical
conductivity is less than or equal to 5 μS/cm; before use, boil it, and cool it down.
4.2 From commonly used standard buffer solutions, choose two for the calibration of
pH meter. Their pH values shall be as close as possible to the expected pH value of
the test specimen. Use water (4.1) for the preparation of the buffer solutions.
5 Instruments
5.1 pH meter: it includes a temperature compensation system; with a precision of at

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