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D6159-23 – Standard Test Method Technical Guide
🔬 Scope and Significance of D6159-23
ASTM D6159-23 specifies a test method for identifying and measuring hydrocarbon impurities in high-purity ethylene using gas chromatography. It targets critical impurities such as methane, ethane, propane, propene, acetylene, iso-butane, propadiene, butane, trans-2-butene, butene-1, isobutene, cis-2-butene, methyl acetylene, and 1,3-butadiene. The purity is calculated by subtracting the sum of impurities from 100.00%. This standard is suitable for setting specifications, internal quality control, and development or research work in ethylene production.
| 🟦 No. | 📏 Impurity | ⚡ Formula |
|---|---|---|
| 1 | Methane | CH4 |
| 2 | Ethane | C2H6 |
| 3 | Propane | C3H8 |
| 4 | Propene | C3H6 |
| 5 | Acetylene | C2H2 |
| 6 | iso-Butane | C4H10 |
| 7 | Propadiene | C3H4 |
| 8 | Butane | C4H10 |
| 9 | trans-2-Butene | C4H8 |
| 10 | Butene-1 | C4H8 |
| 11 | Isobutene | C4H8 |
| 12 | cis-2-Butene | C4H8 |
| 13 | Methyl acetylene | C3H4 |
| 14 | 1,3-Butadiene | C4H6 |
⚙️ Analytical Procedure and Column Configuration
The gaseous ethylene sample is analyzed as received, with injection into a capillary gas chromatograph via direct valve or split valve injection. The GC is equipped with a 6-port sampling valve and two wide bore capillary columns connected in series: a dimethyl polysiloxane column and a PLOT Al2O3/KCl column. A flame ionization detector (FID) is used, and the integrated peak areas are corrected for detector response to quantify impurities.
| 🟦 Component | 📏 Detail | 🎯 Purpose |
|---|---|---|
| Injection | Direct valve or split valve | Sample introduction |
| Sampling Valve | 6-port | Precise injection |
| Column 1 | Dimethyl polysiloxane | Wide bore capillary |
| Column 2 | PLOT Al2O3/KCl | Porous layer open tubular |
| Detector | Flame ionization (FID) | Hydrocarbon detection and quantification |
📊 Data Reporting and Purity Calculation
Results are reported in ppmV (parts per million by volume) and ppmMol. The method is validated for the concentration range of 4 ppmV to 340 ppmV (2 mg/kg to 204 mg/kg). Total impurities are calculated from the sum of individual hydrocarbon levels, and ethylene purity is derived by subtracting this total from 100.00%. Interlaboratory studies confirm precision within this range.
💡 Tip: This method is ideal for specification setting and routine quality control in high-purity ethylene manufacturing processes.
⚠️ Caution: D6159-23 does not detect non-hydrocarbon impurities (e.g., H2O, CO, CO2, alcohols). For comprehensive analysis, refer to ASTM D2504 for noncondensable gases and D2505 for CO2.
❓ Frequently Asked Questions
🔍 What is the purpose of D6159-23?
To determine specific hydrocarbon impurities in high-purity ethylene for quality assurance, specification setting, and research applications.
💡 What columns are specified?
Two wide bore capillary columns in series: a dimethyl polysiloxane column and a PLOT Al2O3/KCl column.
⚡ How is ethylene purity calculated?
By subtracting the total percentage of all detected impurities from 100.00%, with results expressed in ppmV and ppmMol.
📌 What concentration range is covered?
The method is validated from 4 ppmV to 340 ppmV (equivalent to 2 mg/kg to 204 mg/kg).