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GB/T 14571.3-2022: Test method of ethylene glycol for industrial use - Part 3: Determination of content of aldehydes Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid GB/T 14571.3: Historical versions
Similar standardsGB/T 14571.3-2022: Test method of ethylene glycol for industrial use - Part 3: Determination of content of aldehydes---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT14571.3-2022 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 71.080.60 CCS G 16 Replacing GB/T 14571.3-2008 Test method of ethylene glycol for industrial use - Part 3. Determination of content of aldehydes Issued on. JULY 11, 2022 Implemented on. FEBRUARY 01, 2023 Issued by. State Administration for Market Regulation; Standardization Administration of the People's Republic of China. Table of ContentsForeword... 3 Introduction... 5 1 Scope... 6 2 Normative references... 6 3 Terms and definitions... 6 4 Spectrophotometry... 7 5 Liquid chromatography... 9 6 Presentation of analysis results... 13 7 Precision... 14 8 Quality assurance and control... 14 9 Report... 14ForewordThis 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.Determination of acidity - Titration method; - Part 2.Determination of purity and impurities - Gas chromatography; - Part 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); f) Liquid chromatography is added (see Chapter 5 of this Edition); g) Repeatability for spectrophotometry is changed. The repeatability and reproducibility of liquid chromatography are added (see Chapter 7 of this Edition, Chapter 9 of Edition 2008). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing authority shall not be held responsible for identifying any or all such patent rights. This document was proposed by China Petroleum and Chemical Industry Federation. This document shall be under the jurisdiction of National Technical Committee on Chemical of Standardization Administration of China (SAC/TC 63). The drafting organizations of this document. Sinopec Shanghai Petrochemical Research Institute. Main drafters of this document. Li Lanting, Jing Xinyao, Zhuang Haiqing, Wang Chuan, Zhang Yuhong, Peng Zhenlei. This document was issued in 1993 for the first time. The first revision was in 2008.This is the second revision.1 ScopeThis 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 referencesThe 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 values3 Terms and definitionsThis document does not have terms and definitions that need to be defined.4 Spectrophotometry4.1 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. 4.2 Reagents and materials 4.2.1 General Unless otherwise specified, the reagents used are analytically pure, and the water used complies with the specifications for grade three water specified in GB/T 6682. 4.3 Instruments 4.3.1 Spectrophotometer Accuracy. 0.001Abs. 4.3.2 Absorption pool Optical path is 10mm. 4.3.3 Analytical balance Accuracy is 0.1mg. 4.4 Sampling Take samples according to the requirements of GB/T 3723 and GB/T 6680. 4.5 Analysis steps 4.5.1 Inspection of MBTH solution absorbance Take the MBTH solution (4.2.2) in the 10mm absorption cell. Use water as reference solution. Measure the absorbance value of the solution at 350nm, 375nm and 400nm. Record this value. It shall not be greater than 0.020, 0.010, 0.010. 4.6 Calculation On the working curve drawn according to 4.5.2, check the mass m1 (μg) of aldehyde according to the net absorbance. Then calculate the aldehyde content (as formaldehyde) in the specimen according to formula (1).5 Liquid chromatography5.1 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. 5.2 Reagents and materials 5.2.1 General Unless otherwise specified, the reagents used are analytically pure, and the water used conforms to the specifications of grade one water specified in GB/T 6682. 5.2.2 Acetonitrile Liquid chromatography (HPLC) level. 5.2.3 Hydrochloric acid The content is 36.0%~38.0% (mass fraction). 5.2.7 Dilute hydrochloric acid (1mol/L) Pipette 9mL of hydrochloric acid (5.2.3) into a 100mL volumetric flask. Use grade one water to set constant volume. Prepare dilute hydrochloric acid solution of which its concentration is about 1mol/L. 5.3 Instruments and equipment 5.3.1 High performance liquid chromatograph. equipped with ultraviolet detector. The peak height produced by formaldehyde with the minimum determination content (0.1mg/kg) specified in this document shall not be lower than 10 times the noise level. 5.4 Instrument operating conditions Recommended typical operating conditions are shown in Table 1.A typical chromatogram is shown in Figure 2.Other chromatographic columns and operating conditions that meet the separation and quantitation requirements specified in this document may be used. 5.5 Sampling Take samples according to the requirements of GB/T 3723 and GB/T 6680. 5.6 Analysis steps 5.6.1 Setting operating conditions Turn on the chromatograph and make necessary adjustments. Set the instrument parameters according to the typical operating conditions shown in Table 1 or other suitable conditions that can obtain the same separation. After the baseline is stable, the sample can be measured. 5.6.3 Specimen determination Weigh (1±0.02)g or an appropriate amount of ethylene glycol specimen and place it in a 25mL volumetric flask. Weigh accurately to 0.1mg. Add 5.0mL of DNPH solution (5.2.8). Shake well. Ultrasound 10min. Use acetonitrile (5.2.2) to set to the constant volume. If the aldehyde content in the specimen exceeds the linear range of the working curve, the specimen amount can be appropriately reduced.6 Presentation of analysis resultsTake the arithmetic mean of the two repeated determination results to represent the analysis results.7 Precision7.1 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 3 Limit (R).8 Quality assurance and control8.1 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.9 ReportThe report shall contain the followings. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. |
