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D367-94 – Standard Test Method Technical Guide
🧪 Test Method Overview and Significance
ASTM D367-94 (Reapproved 2000) covers the determination of xylene-insoluble matter in creosote and creosote-coal tar solutions. This empirical method requires strict adherence to all details for consistent results across laboratories. The test is useful for evaluating and characterizing creosote, serving as an element in establishing uniformity of shipments and sources of supply. Water content must be determined per Test Method D370, and sampling per Test Methods D38.
⚙️ Apparatus and Filter Crucible Preparation
Key apparatus includes porcelain filtering crucibles of 40 mL capacity with fine-porosity bottom (maximum pore diameter 7 μm), a filter flask with crucible adapter and vacuum source, and a balance accurate to 0.5 mg. Diatomaceous silica analytical filter must be dried to constant weight at 105°C and stored tightly. Xylene shall conform to Specification D845 with five-degree distillation range, and acetone must boil at 56.1°C within 1.0°C at 760 mm Hg.
| 🟦 Component | 📏 Specification |
|---|---|
| Filtering Crucible | Porcelain, 40 mL, fine-porosity, max pore diameter 7 μm |
| Balance Accuracy | 0.5 mg |
| Diatomaceous Silica | 0.45–0.55 g, dried at 105°C to constant weight |
| Xylene | Five-degree distillation range, per Specification D845 |
| Acetone | Boiling at 760 mm Hg, 56.1°C within 1.0°C |
To prepare the crucible: clean if used for less than six determinations by removing the mat, washing with distilled water, drying, and igniting in a muffle furnace at about 800°C for 1 hour. Cool slowly in a desiccator. After six determinations, remove residual ash by boiling in 1+1 hydrochloric acid, then distilled water, back wash, and ignite again. Transfer 0.45–0.55 g of diatomaceous silica evenly, dry at 105–110°C for 30 minutes, cool in desiccator, and weigh to 0.5 mg.
📊 Step-by-Step Procedure
Take the original undehydrated sample. If necessary, heat and stir until crystalline material dissolves and the sample is homogeneous. Determine water content per Test Method D370. Weigh the prescribed sample size into a 100 mL beaker. Digest in hot xylene, then filter through the prepared crucible using vacuum. Wash the insoluble matter with xylene and acetone. Dry and weigh the residue to the nearest 0.5 mg. The xylene-insoluble content is calculated as a percentage of the sample weight. All weighings are recorded to 0.5 mg.
Tip: Ensure diatomaceous silica is evenly distributed to avoid channeling. The drying step at 105–110°C for exactly 30 minutes is critical for consistent moisture removal.
Warning: Xylene and acetone are flammable and toxic. Use in a fume hood and follow all safety protocols. Discard solvents properly per regulations.
❓ Frequently Asked Questions
🔍 What is the purpose of this test method?
It determines xylene-insoluble matter in creosote, which helps evaluate quality and uniformity of shipments and sources of supply.
💡 How is the filter crucible prepared?
Clean the crucible, add 0.45–0.55 g diatomaceous silica, dry at 105–110°C for 30 minutes, cool in desiccator, and weigh to 0.5 mg.
⚡ What is the role of diatomaceous silica?
It acts as a filtering aid to retain insolubles. The specified grade must be used to maintain consistent porosity.
📌 Why is water content measured?
Water content is determined per Test Method D370 to correct for moisture, ensuring the xylene-insoluble measurement reflects only solid impurities.