This standard specifies a method for determining the pH value of the aqueous extract of textiles.
This standard is applicable to the textiles in any form.
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, the parties whose enter into agreement according to these specifications are encouraged to research whether the latest editions of these labels are applied or not. For undated references, the latest edition of the normative document is applicable to these specifications.
GB/T 6682 "Water for Analytical Laboratory Use-Specification and Test Methods" (GB/T 6682-2008, ISO 3696: 1987, MOD)
3 Terms and Definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
pH value
The negative logarithm of hydrogen ion concentration in an aqueous extract.
4 Principle
The pH value of an aqueous extract of a textile is measured at room temperature by means of a pH meter with glass electrode.
5 Reagents
All reagents used shall be the analytical pure.
5.1 Distilled water or deionized water, at least meeting the requirements on Grade 3 water as defined in GB/T 6682, having a pH value between 5.0 and 7.5. The pH value of water shall be tested the first time the water is used. If it is not within the specified range, the water may be redistilled using the glassware with stable chemical properties or other methods may be adopted to make the pH value of water reach the standard. Acid or organic matter may be removed by distilling water from a solution of 1g/L potassium permanganate and 4g/L sodium hydroxide. Alkali (e.g. the presence of ammonia) may be removed by distilling the dilute sulfuric acid. If the distilled water is not Grade 3, 100mL distilled water may be boiled in a beaker at an appropriate rate for (10±1)min, and the beaker shall be covered to let the water cool to the room temperature.
5.2 Potassium chloride solution, 0.1 mol/, prepared using distilled water or deionized water (see 5.1).
5.3 Buffer solution, used for calibration of the pH meter before measurement, which may be prepared by making reference to those specified in Appendix A, having a pH value similar to that of the to-be-measured solution. The buffer solutions having a pH value around 4, 7 or 9 are recommended.
