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D4367-22 – Standard Test Method Technical Guide
⚗️ Principle of Operation and Test Apparatus
ASTM D4367-22 specifies a dual-column gas chromatography method with a backflush system and a flame ionization detector (FID). The liquid specimen, containing a methyl ethyl ketone (MEK) internal standard, is injected into a 0.8-m (2.5-ft) column packed with the nonpolar methyl silicone phase. This column separates hydrocarbons by boiling point. After octane elutes, the carrier gas flow through this column is reversed, flushing out all components heavier than octane. The octane and lighter components then pass through a second 4.6-m (15-ft) column packed with the highly polar phase 1,2,3-tris(2-cyanoethoxy)propane, which effectively resolves the aromatic compounds, including benzene, from the nonaromatic compounds. The eluted components are detected by the FID and recorded on a strip chart. The concentration of benzene is calculated by referencing the peak areas to the known concentration of the internal standard.
| 🟦 Column Configuration | 📏 Specification |
|---|---|
| Column 1 (Nonpolar) | 0.8 m (2.5 ft) × 3.2 mm (⅛ in.) OD stainless steel packed with methyl silicone |
| Column 2 (Highly Polar) | 4.6 m (15 ft) × 3.2 mm (⅛ in.) OD stainless steel packed with 1,2,3-tris(2-cyanoethoxy)propane |
| Detector | Flame Ionization Detector (FID) |
| Internal Standard | Methyl Ethyl Ketone (MEK) |
⚡ Critical Performance Check: The detector-recorder system must produce a minimum deflection of 4 mm for a 1 µL injection of a specimen containing 0.05 volume % MEK at maximum sensitivity.
📊 Key Specifications and Health Significance
This test method is validated for quantifying benzene in hydrocarbon solvents across a concentration range of 0.01 to 1 volume %. For levels