ISO 25122:2026

ISO 25122:2026 is an ISO standard for measuring trace carbon monoxide and carbon dioxide in ethylene and propylene for industrial use. It specifies a gas chromatographic (GC) method for samples with carbon monoxide and carbon dioxide concentrations greater than 0,5 mL/m3, so laboratories can quantify low-level impurities in these feedstocks and products.

What does ISO 25122:2026 specify?

ISO 25122:2026 specifies the GC method, the equipment setup, the sampling route, the calculation approach, and the way the result is reported for carbon monoxide and carbon dioxide in ethylene and propylene. The document is organized into Clauses 1 to 13, covering scope, references, terms, principle, reagents, apparatus, sampling, procedure, calculation, reporting, precision, quality assurance, and the test report.

The practical focus is on routine laboratory analysis. Clause 6 gives two instrument arrangements, Clause 8 sets the calibration and measurement steps, and Clause 11 provides precision statements for judging how well repeated results agree.

What are the key requirements of ISO 25122:2026?

ISO 25122:2026 requires a GC system that can separate carbon monoxide and carbon dioxide and then measure them after conversion to methane. In practice, this means the laboratory needs a working chromatograph, a methanizer, and a detector setup that can reliably see very small impurity peaks.

• Applicable sample range - The method applies to ethylene and propylene when carbon monoxide and carbon dioxide are above 0,5 mL/m3. This defines when the method is suitable for routine product control.
• Measurement principle - Clause 4 uses a packed-column GC system, then catalytic hydrogenation in a methanizer to convert carbon monoxide and carbon dioxide to methane for detection by hydrogen flame ionization detector (FID). This matters because the detector does not measure the original gases directly.
• Reagents and gases - Clause 5 requires high-purity nitrogen, hydrogen and air, all dried and purified, plus a gas standard with known carbon monoxide and carbon dioxide content. The base gas for the standard must not contain measurable target gas, or the standard has to be corrected.
• Instrument performance - Clause 6.1 requires the instrument to produce an impurity peak at 0,5 mL/m3 that is at least three times the background noise. That performance check helps ensure the method can actually detect the specified trace level.
• Two operating configurations - Clause 6.1 gives two arrangements: condition 1 with one valve and two columns, and condition 2 with two valves and three columns. Condition 2 adds better separation of oxygen from carbon monoxide, which is important when oxygen might interfere.
• Columns and typical settings - Clause 6.2 and Table 1 describe packed columns, operating temperatures, flow rates, injection volume, and backflush timing. This gives the lab a validated starting point for setup and troubleshooting.
• Sampling and injection - Clause 7 points to ISO 7382 or ISO 8563 for sampling. Clause 8 requires 2 mL injections, duplicate measurements for both standard and sample, and liquid propylene to be fully vaporized before analysis.
• Calculation and reporting - Clause 9 calculates content from the ratio of sample peak area to standard peak area, and Clause 10 reports the arithmetic mean of two results to the nearest 0,1 mL/m3. This keeps reporting consistent between laboratories.

What terms does ISO 25122:2026 define?

ISO 25122:2026 does not add a separate list of formal definitions, but several technical terms are central to the method.

• Gas chromatography (GC) - The separation technique used to isolate carbon monoxide and carbon dioxide from the sample matrix.
• Hydrogen flame ionization detector (FID) - The detector used after methanization to measure the methane formed from the target gases.
• Methanizer - A nickel-catalyst device that converts carbon monoxide and carbon dioxide into methane before detection.
• Quality control (QC) - A known-content check sample used to verify that results remain accurate over time.
• Repeatability (r) - The closeness of two results from the same operator and apparatus under the same conditions.
• Reproducibility (R) - The closeness of results from different laboratories using the same method on the same material.
• Backflush - The valve action used to clear earlier-eluting matrix components from the column path after the target components have passed.

Who uses ISO 25122:2026?

ISO 25122:2026 is used by industrial gas laboratories, quality control teams, and contract testing laboratories that measure impurities in ethylene and propylene. It is also relevant to producers, buyers, and technical managers who need a traceable method for release testing, incoming inspection, or product quality checks.

Sampling staff use the document together with ISO 7382 or ISO 8563. Laboratory analysts use it to set up the GC system, calibrate with gas standards, run duplicate tests, and record the final result for reporting.

Which standards are used with ISO 25122:2026?

ISO 25122:2026 uses two normative references for sampling:

• ISO 7382 - Sampling of ethylene in the liquid and gaseous phase, used when the test material is ethylene.
• ISO 8563 - Sampling of propylene and butadiene in the liquid phase, used when the test material is propylene.

These references matter because the analytical result depends on how the sample is taken and transferred to the GC system.

What does the ISO 25122:2026 document contain?

ISO 25122:2026 contains the operating principle, reagent requirements, apparatus description, sampling instructions, procedure, calculation, reporting rules, precision statements, quality assurance, and test report content. It also includes Table 1 with columns and typical operating conditions, and Figures 1 and 2 showing the two instrument configurations.

Figures 3 and 4 show typical chromatograms for the two operating conditions. Table 2 gives repeatability and reproducibility statements for the method, and Clause 9 gives the calculation formula based on peak-area comparison with the gas standard.