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D2007-19 – Standard Test Method Technical Guide
🔬 Scope and Classification Overview
This test method, designated D2007‑19, covers a clay‑gel absorption chromatographic procedure for classifying oil samples with an initial boiling point of at least 260 °C (500 °F) into the hydrocarbon types: polar compounds, aromatics, and saturates. It also allows recovery of representative fractions of these types. This classification is used for specification purposes in rubber extender and processing oils. For further classification guidance, see Test Method D2226.
The method is not directly applicable to oils with more than 0.1 % by mass n‑pentane insolubles; such oils may be analyzed after removal of these materials, but precision may be degraded (see Appendix X1). Values are stated in SI units with inch‑pound units in parentheses. Specific safety warnings are given in Sections 6.1, 7, A1.4.1, and A1.5.5.
📐 Key Hydrocarbon Definitions
As defined in Section 3 of the standard, the following terms refer to the hydrocarbon types and structural groups measured by this test method:
| 🟦 Type | 📏 Description |
|---|---|
| Saturates | Material that, on percolation in n‑pentane eluent, is not adsorbed on either clay or silica gel. |
| Aromatics | Material that passes through a column of adsorbent clay in n‑pentane but adsorbs on silica gel under the specified conditions. |
| Polar Compounds (Polar Aromatics) | Material retained on the adsorbent clay after percolation of the sample in n‑pentane eluent. |
| Asphaltenes (n‑pentane insolubles) | Insoluble matter that precipitates from a solution of oil in n‑pentane under the specified conditions. |
⚙️ Test Procedure and Precision
The procedure involves percolating the oil sample through columns packed with adsorbent clay and silica gel, using n‑pentane as the eluent. Saturates pass through both columns, aromatics are adsorbed on the silica gel but pass through the clay, and polar compounds are retained on the clay