GB/T 4348.1-2026 Component determination of sodium hydroxide for industrial use—Part 1: Sodium hydroxide and sodium carbonate English, Anglais, Englisch, Inglés, えいご
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ICS 13.220.10
CCS H 57
National Standard of the People's Republic of China
GB/T 4348.1-2026
Replaces GB/T 4348.1-2013
Component determination of sodium hydroxide for industrial use - Part 1: Sodium hydroxide and sodium carbonate
工业用氢氧化钠成分分析 第1部分：氢氧化钠和碳酸钠
Issue date: 2026-01-28 Implementation date: 2027-02-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
Introduction
1 Scope
2 Normative References
3 Terms and Definitions
4 Principle
5 Reagents or Materials
6 Apparatus
7 Test Methods
8 Calculation of Results
9 Test Report
Analysis of Sodium Hydroxide for Industrial Use – Part 1: Sodium Hydroxide and Sodium Carbonate
Warning — Personnel using this document should have practical experience in regular laboratory work. This document does not purport to address all the possible safety problems associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and ensure compliance with any national regulatory conditions.
1 Scope
This document describes the test principles and test methods for the determination of sodium hydroxide and sodium carbonate content in sodium hydroxide for industrial use, and specifies the reagents or materials, apparatus, result calculation, and test report content for the determination.
This document applies to the determination of sodium hydroxide and sodium carbonate content in sodium hydroxide for industrial use.
2 Normative References
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 601 Chemical reagent – Preparations of standard volumetric solutions
GB/T 603 Chemical reagent – Preparations of reagent solutions for use in test methods
GB/T 6682 Water for analytical laboratory use – Specification and test methods
GB/T 9725 Chemical reagent – General rule for potentiometric titration
3 Terms and Definitions
No terms and definitions are required for this document.
4 Principle
4.1 Principle of Determination of Sodium Hydroxide Content
Barium chloride is first added to the sample solution to convert sodium carbonate into a barium carbonate precipitate, followed by titration with a standard volumetric solution of hydrochloric acid. The titration endpoint is indicated by phenolphthalein indicator solution or determined by the abrupt change in electrode potential using potentiometric titration.
The reactions are as follows:
[Reactions would be shown here in a formal document]
4.2 Principle of Determination of Sodium Carbonate Content
The sample solution is titrated with a standard volumetric solution of hydrochloric acid using bromocresol green-methyl red indicator solution until the endpoint, determining the sum of sodium hydroxide and sodium carbonate. The sodium carbonate content is then calculated by subtracting the sodium hydroxide content (determined in 4.1) from the total.
5 Reagents or Materials
5.1 Unless otherwise specified, the reagents and water used in this document refer to analytically pure reagents and grade 3 water (carbon dioxide free) as specified in GB/T 6682. The required standard volumetric solutions, preparations, and products shall be prepared according to GB/T 601 and GB/T 603.
5.2 Barium chloride solution: 100 g/L.
Before use, neutralize to a slight pink color using a sodium hydroxide standard volumetric solution, with phenolphthalein (5.4) as indicator.
5.3 Standard volumetric hydrochloric acid solution: c(HCl) = 1 mol/L.
5.4 Phenolphthalein indicator solution: 10 g/L.
5.5 Bromocresol green-methyl red indicator solution.
6 Apparatus
6.1 One-mark pipettes: 25 mL, 50 mL, Class A.
6.2 Burette: 50 mL, division value 0.1 mL, Class A.
6.3 One-mark volumetric flask: 500 mL, Class A.
6.4 Magnetic stirrer.
6.5 Potentiometric titrator: Accuracy 2 mV; Electrodes: glass-saturated calomel electrode or combined pH electrode.
6.6 Balance: Accurate to 0.01 g.
6.7 Analytical balance: Accurate to 0.0001 g.
7 Test Methods
7.1 Preparation of Test Solution
7.1.1 Test Solution A
Using a dry, clean weighing bottle of known mass, quickly weigh (15 ± 1) g of solid sodium hydroxide or (25 ± 1) g of liquid sodium hydroxide (accurate to 0.01 g) from the sample bottle. Place the weighed sample into a beaker containing approximately 200 mL of water, cool to room temperature, transfer to a 500 mL volumetric flask, rinse the weighing bottle and beaker, add the rinsings to the volumetric flask, dilute to the mark, and mix well.
7.1.2 Test Solution B
Using a dry, clean conical flask or the titration cup of a potentiometric titrator, quickly weigh an amount of liquid sodium hydroxide equivalent to 0.7 g - 0.8 g of NaOH (accurate to 0.0001 g), immediately add approximately 50 mL of water, and mix well. This is used for the determination of sodium hydroxide content.
7.2 Determination of Sodium Hydroxide Content
7.2.1 Indicator Method
7.2.1.1 Determination using Test Solution A
Use a one-mark pipette to transfer 50 mL of Test Solution A into a 250 mL conical flask. Add 10 mL of barium chloride solution and 2 to 3 drops of phenolphthalein indicator solution. Titrate with the standard volumetric hydrochloric acid solution under magnetic stirring until the slight pink color just disappears (the endpoint). Record the volume of standard volumetric hydrochloric acid solution consumed.
7.2.1.2 Determination using Test Solution B
To Test Solution B, add 5 mL of barium chloride solution and 2 to 3 drops of phenolphthalein indicator solution. Titrate with the standard volumetric hydrochloric acid solution under magnetic stirring until the slight pink color just disappears (the endpoint). Record the volume of standard volumetric hydrochloric acid solution consumed.
7.2.2 Potentiometric Titration Method
7.2.2.1 Determination using Test Solution A
Use a one-mark pipette to transfer 25 mL of Test Solution A into the titration cup of the potentiometric titrator or into a beaker. Add 5 mL of barium chloride solution and approximately 30 mL of water. Titrate with the standard volumetric hydrochloric acid solution under magnetic stirring according to GB/T 9725. The titration endpoint is determined automatically by the instrument or by the graphical method or the second
