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Plastics - Determination of hexamethylenetetramine content in phenolic resins - Kjeldahl method, perchloric acid method and hydrochloric acid method
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Plastics -- Phenolic resins -- Determination of hexamethylenetetramine content -- Kjeldahl method, perchloric acid method and hydrochloric acid method
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Basic data
| Standard ID | GB/T 33317-2025 (GB/T33317-2025) |
| Description (Translated English) | Plastics - Determination of hexamethylenetetramine content in phenolic resins - Kjeldahl method, perchloric acid method and hydrochloric acid method |
| Sector / Industry | National Standard (Recommended) |
| Classification of Chinese Standard | G31 |
| Classification of International Standard | 83.080.10 |
| Word Count Estimation | 10,156 |
| Date of Issue | 2025-10-05 |
| Date of Implementation | 2026-05-01 |
| Older Standard (superseded by this standard) | GB/T 33317-2016 |
| Issuing agency(ies) | State Administration for Market Regulation and Standardization Administration of China |
GB/T 33317-2025: Plastics - Determination of hexamethylenetetramine content in phenolic resins - Kjeldahl method, perchloric acid method and hydrochloric acid method
---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
ICS 83.080.10
CCSG31
National Standards of the People's Republic of China
Replaces GB/T 33317-2016
Determination of hexamethylenetetramine content in phenolic resin for plastics
Kjeldahl method, perchloric acid method and hydrochloric acid method
(ISO 8988.2006,Plastics-Phenolicresins-Determinationof
Released on October 5, 2025; to be implemented on May 1, 2026.
State Administration for Market Regulation
The State Administration for Standardization issued a statement.
Foreword
This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1.Structure and Drafting Rules of Standardization Documents".
Drafting.
This document replaces GB/T 33317-2016 "Determination of Hexamethylenetetramine Content in Plastic Phenolic Resins - Kjeldahl Method and High Chlorine Content".
Compared with GB/T 33317-2016, the main technical changes in "Acid Method and Hydrochloric Acid Method" are as follows, except for structural adjustments and editorial modifications.
---A new chapter on "Terms and Definitions" has been added (see Chapter 3);
--- An automatic potentiometric titration method has been added to the perchloric acid method (see 5.5.2).
This document is modified to adopt ISO 8988.2006 "Determination of hexamethylenetetramine content in phenolic resins—Phenolic plastics—Kjeldahl nitrogen determination method, high chlorine content—"
Acid method and hydrochloric acid method.
The technical differences between this document and ISO 8988.2006, and the reasons therefor, are as follows.
---The unit for the requirements of mass and analytical balance precision in the standard has been changed to mg (see 4.3.6, 4.4.4, 4.5.1, 5.4.5).
(5.5.1.1, 5.5.1.2, 5.5.2.2, 6.4.3, 6.5.1, 6.5.2) for ease of use;
---ISO 385 (see 4.4.3) has been replaced with the normatively referenced GB/T 12805 to adapt to my country's technical conditions and increase operability.
Actual nature;
---The calculation formula has been changed to use the actual concentration of the solution (see 4.6). The international standard directly uses 0.10 for solution concentration.
Substituting 0.20 into the calculation will result in a deviation when the actual concentration is prepared. Using the actual concentration of the solution can improve the accuracy of the results.
---The reproducibility requirement in 3.7 of ISO 8988.2006 is listed and explained in this standard (see 4.7), because the Kjeldahl method has not yielded [reproducibility details].
Obtain relevant data from inter-laboratory pairs;
---Automatic potentiometric titration has been added to the perchloric acid method (see 5.5.2). With the development of modern analytical techniques, automatic potentiometric titration has become increasingly important.
Its accuracy and automated operation are becoming increasingly widely adopted, therefore this method has been added to this document;
---The normative reference GB/T 601 (see 5.3.4) has been added because the automatic potentiometric titration method has been added to the perchloric acid method in this paper.
The following minimal editorial changes have been made to this document.
---The standard title has been revised to "Determination of Hexamethylenetetramine Content in Phenolic Resins of Plastics. Kjeldahl Method, Perchloric Acid Method, and Hydrochloric Acid Method".
Law".
Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents.
This document was proposed by the China Petroleum and Chemical Industry Federation.
This document is under the jurisdiction of the National Technical Committee on Plastics Standardization (SAC/TC15).
This document was drafted by. Shandong Shengquan New Material Co., Ltd., Zhonglan Chenguang Chemical Co., Ltd., and Shandong Provincial Product Quality Inspection and Research Institute.
Research Institute, Zhonglan Chenguang Chengdu Testing Technology Co., Ltd., Zibo Municipal Institute of Inspection, Testing and Metrology, Zhejiang Chenxiang Plastics Co., Ltd., Jilin Province
Product Quality Supervision and Inspection Institute, Shandong Tiancheng Wanfeng Chemical Technology Co., Ltd.
The main drafters of this document are. Zhang Xiumei, Wang Xuyi, Wang Qi, Wang Jiandong, Shen Yanling, Shi Xinyu, Fang Yong, Gao Yue, Li Shangyu, and Gao Jianguo.
Zhu Niande.
The release history of this document and the document it replaces is as follows.
---First published in.2016 as GB/T 33317-2016;
---This is the first revision.
Determination of hexamethylenetetramine content in phenolic resin for plastics
Kjeldahl method, perchloric acid method and hydrochloric acid method
Warning---Personnel using this document should be familiar with standard laboratory operating procedures. This document is not intended to address all potential issues related to the use of this document.
Regarding related safety issues, users are responsible for establishing appropriate safety and health operating procedures and ensuring compliance with all regulatory requirements.
1 Scope
This document describes three methods for determining the hexamethylenetetramine content in phenolic resins. These three methods are equivalent.
The Kjeldahl method is not applicable to phenolic resins containing other nitrogen compounds, nor to resins containing additives that can be oxidized by perchloric acid.
The perchloric acid process is not suitable for phenolic resins containing other acidic or alkaline substances, nor for resins containing additives that can be oxidized by perchloric acid.
The hydrochloric acid method is not suitable for phenolic resins containing other acidic or alkaline substances.
2 Normative references
The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.
For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies.
This document.
GB/T 601 Preparation of Standard Titration Solutions for Chemical Reagents
GB/T 12805 Burettes for Laboratory Glassware
3 Terms and Definitions
This document does not contain any terms or definitions that need to be defined.
4.Kjeldahl method for nitrogen determination
4.1 General Provisions
Chapter 4 specifies the method for determining the total nitrogen content in phenolic resins, calculated as hexamethylenetetramine. This method is applicable to hexamethylenetetramine.
Phenolic resin with a content of ≥0.5% (mass fraction).
4.2 Principle
In the presence of a catalyst, hexamethylenetetramine in the sample was degraded into ammonium bisulfate in concentrated sulfuric acid. Ammonium bisulfate reacts with sodium hydroxide.
The reaction produces sodium sulfate and ammonia. The ammonia is distilled off and collected in a hydrochloric acid solution. Excess hydrochloric acid is titrated with a standard sodium hydroxide solution in the presence of an indicator.
Titration with a fixed solution.
4.3 Reagents
4.3.1 Concentrated sulfuric acid. analytical grade.
4.3.2 Kjeldahl mixed catalyst. composed of 97g sodium sulfate decahydrate (Na2SO4·10H2O), 1.5g copper sulfate pentahydrate (CuSO4·5H2O), and
...