GB/T 14571.3-2022Test method of ethylene glycol for industrial use - Part 3: Determination of content of aldehydes (English PDF)

Foreword

This document was drafted in accordance with the rules given in GB/T 1.1-2020 "Directives for standardization - Part

1.Rules for the structure and drafting of standardizing documents". This document is Part 3 of GB/T 14571 "Test method of ethylene glycol for industrial use". The following parts of GB/T 14571 have been issued. - Part

1 Scope

GB/T 14571.3-2022 is the Chinese national standard on test method of ethylene glycol for industrial use - part 3: determination of content of aldehydes, in the field of chemical technology. The /T suffix marks it as a recommended standard: it is not compulsory by itself, but it becomes binding as soon as a contract, a tender or a customer specification calls it up - which in practice is how most foreign buyers meet it. It was issued on 11 July 2022 by the State Administration for Market Regulation; Standardization Administration of China, and has been in force since 1 February 2023. Classification: ICS 71.080.60, CCS G16. This page is published from the official record of the standard held by the Chinese standards administration: the identification, the dates, the classification and the issuing body are taken from there. The clause text, the tables and the numeric limits are in the document itself, which is delivered complete in English translation.

This document specifies spectrophotometric and liquid chromatographic methods for the determination of aldehydes in ethylene glycol for industrial use. This document applies to the determination of aldehyde content in industrial ethylene glycol. The determination range is 0.10mg/kg~50mg/kg. If the ethylene glycol sample contains ketones, the liquid chromatography analysis results will be high. Therefore, when applying this document to the quality control of the aldehyde content of ethylene glycol products, relevant parties shall negotiate to determine the analytical method to be used.

2 Normative references

The following referenced documents are indispensable for the application 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 3723, Sampling of chemical products for industrial use - Safety in sampling

GB/T 6680, General rules for sampling liquid chemical products

GB/T 6682, Water for analytical laboratory use - Specification and test methods

GB/T 8170, Rules of rounding off for numerical values and expression and judgement of limiting values

3 Determination of content of aldehydes; - Part

4.Determination of ultraviolet transmittance - Ultraviolet spectrophotometric method; - Part

5.Determination of chloride ion - Ion chromatography. This document replaces GB/T 14571.3-2008 "Ethylene glycol for industrial use - Determination of content total aldehydes present - Spectrophotometric method". Compared with GB/T 14571.3-2008, in addition to the structural adjustments and editorial changes, the main technical changes in this document are as follows:

a) The spectrophotometric formaldehyde solution specification requirements are changed, from formaldehyde ( >36% aqueous solution) to formaldehyde aqueous solution (100mg/L) (see

4.2.4 of this Edition,

4.4 of Edition 2008);

b) The preparation method of the spectrophotometric formaldehyde standard solution is changed (see

4.2.5 of this Edition,

4.5 of Edition 2008);

c) The inspection of MBTH solution absorbance is added (see

4.5.1 of this Edition);

d) The calculation formula for spectrophotometric aldehyde content is changed (see

4.6 of this Edition,

8.1 of Edition 2008);

e) The measurement unit of aldehyde content is changed from % (mass fraction) to mg/kg (see Chapter 1, Chapter 4~Chapter 7 of this Edition, Chapter 1, Chapter 8 and Chapter 9 of Edition 2008);

4 Spectrophotometry

4.1 Method summary The reaction product of aliphatic aldehyde and 3-methyl-2-benzothiazolinone hydrazone (MBTH) in the specimen is oxidized by ferric chloride under acidic conditions to produce blue-green fused cations.

5 Liquid chromatography

5.1 Method summary The aliphatic aldehyde in the specimen reacts with 2,4-Dinitrophenylhydrazine (DNPH) under acidic conditions, to form DNPH hydrazone derivative, see Figure 1.

6 Presentation of analysis results

Take the arithmetic mean of the two repeated determination results to represent the analysis results.

7 Precision

7.1 Repeatability The absolute value of the two independent test results obtained by the same operator in the same laboratory using the same equipment, according to the same test method, independently on the same object within a short period of time, is not greater than the repeatability limit (r) listed in Table 2.

7.2 Reproducibility In different laboratories, with different equipment operated by different operators, according to the same test method, the absolute difference between the two independent test results obtained by independently testing the same measured object is not greater than the reproducibility listed in Table

8 Quality assurance and control

8.1 The laboratory shall regularly analyze quality control samples to ensure the accuracy of the results.

8.2 Quality control samples shall be stable and representative relative to the analyzed samples.