ISO/DIS 8174:2026(en)

ISO TC 47/ WG 2

Secretariat: JISC

Date: 2025-12-04

Ethylene and propylene for industrial use - Determination of trace oxygenates - Gas chromatographic method

© ISO 2026

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Contents

Foreword iv

1 Scope 1

2 Normative references 1

3 Terms and definitions 1

4 Principle 1

5 Reagents 1

6 Apparatus 2

7 Sampling 4

8 Preparation of Apparatus 4

9 Calibration 4

10 Procedure 4

11 Calculation 4

12 Reporting 5

13 Precision 5

14 Quality Assurance 5

15 Test report 5

Foreword

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This document was prepared by Technical Committee ISO/TC 47, Chemistry.

This second edition cancels and replaces the first edition (ISO 8174:1986), which has been technically revised.

The main changes are as follows:

— the Name of this document has been changed into “Ethylene and propylene for industrial use - Determination of trace oxygenates - Gas chromatographic method”;

— the Scope has been expanded to be applicable for the determination of methanol, dimethyl ether, methyl tert-butyl ether, acetaldehyde, ethanol, propan-2-ol, acetone, and butanone;

— in Clause 1, the determination of acetonitrile has been deleted;

— in Clause 1, the test method has been improved to be suitable for ethylene and propylene with oxygenate concentrations greater than 0,5 mL/m³;

— in Clause 2, the quotation of ISO 6377 has been cancelled;

— in Clause 4, the method principle regarding the analysis procedure has been revised;

— in Clause 5, the preparation of gas standard for calibration has been revised;

— in Clause 6, chromatographic columns have been modified from packed columns to capillary columns;

— in Clause 6, a gas sampling device has been added;

— in Clause 6, the contents related to recording and vaporization devices have been revised;

— in Clause 7, 9 and 10, the content related to sampling, the absorption devices and the concentration operation of original standard and actual samples have been deleted;

— in Clause 9, 10 and 11, the procedure of calibration and sample determination have been revised;

— in Clause 12, the expression of results has been revised;

— in Clause 13, the method precision and bias have been reinvestigated;

— Figure 1 and Figure 2 related to the absorption train and absorption flask details have been deleted;

— Figure 3 representative of the typical chromatogram has been changed and displayed with Figure 1 in Clause 6.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Ethylene and propylene for industrial use – Determination of trace oxygenates – Gas chromatographic method

This document specifies a gas chromatographic method for the determination of trace amounts of oxygenated compounds in ethylene and propylene (propene) for industrial use.

The method is applicable to ethylene and propylene having methanol, dimethyl ether, methyl tert-butyl ether, acetaldehyde, ethanol, propan-2-ol, acetone, and butanone concentrations greater than 0,5 mL/m³.

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.

ISO 7382, Ethylene for industrial use — Sampling in the liquid and the gaseous phase

ISO 8563, Propylene and butadiene for industrial use — Sampling in the liquid phase

No terms and definitions are listed in this document.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/

Under the conditions specified in this document, gaseous (or liquid vaporized) sample is introduced into the chromatographic column by carrier gas through a gas sampling device. Each oxygenated compound is separated and detected using a hydrogen flame ionization detector (FID). The peak area of oxygenates are recorded and the quantification is carried out by external standard method.

WARNING — The gases herein are high-pressure compressed or highly flammable, which shall be paid attention to safety when used.

Methanol used for preparing the gas standard has a purity more than 99,0 % (mass fraction).

Dimethyl ether used for preparing the gas standard has a purity more than 99,0 % (mass fraction).

Methyl tert-butyl ether used for preparing the gas standard has a purity more than 99,0 % (mass fraction).

Acetaldehyde used for preparing the gas standard has a purity more than 99,0 % (mass fraction).

Ethanol used for preparing the gas standard has a purity more than 99,0 % (mass fraction).

Propan-2-ol used for preparing the gas standard has a purity more than 99,0 % (mass fraction).

Acetone used for preparing the gas standard has a purity more than 99,0 % (mass fraction).

Butanone used for preparing the gas standard has a purity more than 99,0 % (mass fraction).

Helium or Nitrogen, having purities more than 99,99 % (volume fraction), dried and purified preferably by silica gel and 5A molecular sieve.

5.10.1 Air, compressed, dried and purified preferably by silica gel and 5A molecular sieve.

5.10.2 Hydrogen, having a purity more than 99,99 % (volume fraction), dried and purified preferably by silica gel and 5A molecular sieve.

The content of each oxygenate in gas standard shall be close to that in actual samples and less than 100 mL per cubic meter in base gas. The oxygenated compounds generally present in ethylene and propylene products shall be contained and the gas standard can be purchased with certificates or self-prepared. The base gas is nitrogen or helium that shall be free of oxygenates to be analysed, otherwise it shall be corrected.

Gas chromatograph fitted with a six-way gas sampling valve of a loop size at 1 mL and a flame ionization detector. The peak height produced by the instrument for impurities at the concentrations of 0,5 mL/m³ shall be at least twice greater than the height of the background noise.

6.2.1 Recommended column and typical operating conditions are described in Table 1. Any other columns and chromatographic conditions giving satisfactory separation for determination and adequate limit of detection may also be used.

Table 1 — Recommended chromatographic columns and typical operating conditions

6.2.2 Typical chromatogram is shown in Figure 1.

Key

1 ethylene or propylene

2 dimethyl ether

3 acetaldehyde

4 methyl tert-butyl ether

5 methanol

6 acetone

7 butanone

8 ethanol

9 propan-2-ol

Figure 1 — Typical chromatogram separated by a CP-Lowox column

An integrator or chromatographic workstation is recommended.

Gas samples are introduced by a six-way gas sampling valve with an injection volume of 1,0 mL.

NOTE If necessary, passivation treatment shall be performed on used sampling cylinders, vaporization devices, gas sampling valves, injection ports, and connecting pipelines, avoiding the adsorption of trace oxygenates.

Liquid propylene can be vaporized using flash vaporization devices, water bath, or other suitable devices. Ensure that the liquid sample is completely vaporized and sample representativeness does not change, i.e. the composition of gas sample introduced by chromatographic sampling device must be consistent with that of the vaporized liquid sample.

Take the laboratory sample in a stainless steel cylinder as specified in ISO 7382 or ISO 8563.

Install and aging the column according to the instrument operating manual. Then set the instrument to the conditions shown in Table 1. Measure when the device is stable.

Using a six-way gas sampling valve, inject 1.0 mL of gas standard (5.11) and record the chromatogram, then identify the peaks and integrate. Repeat twice and calculate the average peak area of each oxygenate for quantitation. The difference between the peak area of two repeated measurements shall not exceed 5 % of its average value.

10.1 Vaporize the liquid propylene thoroughly before introduction into the sampling device. Heat the vaporization device into the recommended temperature. Connect one end of the heating system to the outlet of sample cylinder while assemble the other one with the injection device. Then turn on the cylinder valve and vaporize the liquid sample sufficiently. Flush adequately, by actual sample, when injection with a gas sampling injection valve. Besides, prior sample introduction into the vaporization device, ensure adequate sample pressure well above the vapour pressure of propylene.

10.2 Inject 1,0 mL of gaseous samples with a six-way gas sampling valve, repeat twice, record and measure the peak area of each oxygenated compound.

11.1 The oxygenate contents (φ_i), expressed in milliliters per cubic meter (mL/m³), are given by formula (1):

(1)

where

φ_s is content, in milliliters per cubic meter (mL/m³), of oxygenate i in the gas standard

A_i is area of oxygenate i in sample

A_s is area of oxygenate i in the gas standard

11.2 The oxygenate contents (w_i), expressed in milligrams per kilogram (mg/kg), are given by formula (2):

(2)

where

M is relative molecular mass of oxygenate i in sample

M is relative molecular mass of sample, which is 28,05 for ethylene and 42,08 for propylene

Report the arithmetic mean of two repeated measurements as the analysis result to the nearest 0,1 mg/kg or 0,1 mL/m³.

The difference between two test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the values listed in Table 2 in only one case in twenty.

The difference between two individual and independent test results, obtained by different operators working in different laboratories on identical test material would in the long run, in the normal and correct operation of the test method, exceed the values given in Table 2 in one case in twenty.

Table 2 — Precision statements

14.1 A quality control (QC) sample of known content of carbon monoxide and carbon dioxide shall be analysed periodically throughout a series of analyses to check the functioning of the instrument and the validity of the results.

14.2 The QC sample shall be stable and representative with respect to the sample being analysed, which can be purchased with certificates or be self-prepared in 5.11.

The test report shall include the following information:

a) all information necessary for the complete identification of the sample (name, lot, date, time, and location, etc.);

b) a reference to this International Standard, i.e. ISO 8174;

c) the concentration of each oxygenate as required;

e) details and explanations of any unusual features noted during the determination;

f) name and analysis date of the analyst;

g) details of any operations not included in this International Standard, or in the International Standards to which reference is made or regraded as optional.