Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D5135-21 – Standard Test Method Technical Guide
ASTM D5135-21 specifies a standardized capillary gas chromatographic method for determining the organic impurities in styrene monomer and calculating its purity by difference. This method is vital for evaluating product quality in manufacturing and refining processes.
🔬 Scope and Principle of the Test Method
This test method is applicable to the determination of typical impurities found in commercial styrene, such as ethylbenzene, cumene, and n-propylbenzene, at concentrations up to 1.0 mass %. The procedure utilizes an internal standard (typically n-heptane) which is accurately added to the sample. The concentration of each impurity is quantified by comparing its chromatographic peak area to that of the internal standard, using predetermined relative response factors. The total styrene content is then calculated by subtracting the sum of all identified impurities from 100 %.
🎯 Key Performance Parameters and Detection Limits
The detection capability of the method was rigorously established through an interlaboratory study (ILS) in accordance with Practice E691. The following key metrics were calculated from the ILS data for n-propylbenzene.
| 📊 Parameter | 📏 Value (mass %) | 🎯 Source / Notes |
|---|---|---|
| Limit of Detection (LOD) | 0.0003 | Calculated from ILS results for n-propylbenzene (Table 3) |
| Limit of Quantitation (LOQ) | 0.0010 | Calculated from ILS results for n-propylbenzene (Table 3) |
| Applicable Impurity Range | Up to 1.0 | Total impurity concentration in typical commercial styrene |
| Purity Calculation | By Difference | 100 % − Σ (all detected impurities) |
✅ Compliance Requirement: All test results must be rounded in accordance with Practice E29 for determining conformance with material specifications.
⚙️ Procedure, Safety, and Key References
The analytical procedure involves precise sample preparation with an internal standard, followed by capillary gas chromatography. Column installation must follow Practice E1510, and liquid calibration blends shall be