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D1319-20 – Standard Test Method Technical Guide
The ASTM D1319-20a standard, Standard Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption, provides an established procedure for determining the volume percent of total aromatics, total olefins, and total saturates. It is widely used for specifying automotive spark-ignition engine fuels, including gasolines blended with oxygenates.
🎯 Scope and Applicability
This test method is designed for petroleum fractions that distill below 315 °C. It is specifically intended for full boiling range products, as the precision does not apply to narrow boiling fractions near the 315 °C limit. The method is also applicable to automotive spark-ignition engine fuels, including those blended with oxygenates like MTBE and ethanol.
Critical Limitation: Samples containing dark-colored components that interfere with reading the fluorescent indicator adsorption bands cannot be analyzed by this method.
⚠️ Important Limitation: The applicability of this test method to products derived from fossil fuels other than petroleum (e.g., coal, shale, or tar sands) has not been determined. The precision statement may or may not apply to such products.
⚙️ Test Method Principles and Interferences
The method separates hydrocarbon types using fluorescent indicator adsorption. Oxygenated blending components at commercial concentrations do not interfere, as they elute with the alcohol desorbent instead of the hydrocarbon bands.
Verified Non-Interfering Oxygenates: Methanol, ethanol, methyl-tert-butylether (MTBE), tert-amylmethylether (TAME), and ethyl-tert-butylether (ETBE). Other oxygenated compounds must be individually verified for interference.
💡 Tip for Oxygenated Samples: When analyzing samples containing oxygenated blending components, the results must be mathematically corrected to a total sample basis to account for the volume of oxygenates.
📊 Working Ranges and Precision Statements
The standard provides two distinct precision statements (Table 3 and Table 4) based on the sample matrix and concentration ranges.
| 🟦 Hydrocarbon Type | 📏 Table 3 Range (% v/v) | 📐 Table 4 Range (% v/v) |
|---|---|---|
| Total Aromatics | 5 % – 99 % | 13 % – 40 % |
| Total Olefins | 1 % – 55 % | 4 % – 33 % |
| Total Saturates | 1 % – 95 % | 45 % – 68 % |
| 🎯 Sample Type | ⚡ Recommended Precision Table |
|---|---|
| Petroleum fractions (final BP < 315 °C) & non-oxygenated automotive gasolines outside Table 4 ranges. | Table 3 |
| Oxygenated (MTBE, ethanol) and non-oxygenated automotive spark-ignition engine fuels. | Table 4 |
Bias Correlation (Practice D6708): A relative bias section correlates D1319 total aromatic results with Test Method D5769 for spark-ignition engine fuels. This correlation applies to total aromatics from 3.3 % to 34.4 % by volume (as measured by D1319) and a T95 distillation temperature between 149.1 °C and 196.6 °C.
❓ Frequently Asked Questions
🔍 What is the maximum distillation temperature for samples analyzed by D1319?
The test method is intended for petroleum fractions that distill below 315 °C. The precision does not apply to narrow boiling fractions near this 315 °C limit.
💡 Which oxygenates are verified as non-interfering?
Methanol, ethanol, MTBE, TAME, and ETBE do not interfere with the determination of hydrocarbon types as they elute with the alcohol desorbent.
📌 When should Table 4 precision be used over Table 3?
Table 4 is applicable for automotive spark-ignition engine fuels (oxygenated and non-oxygenated) within the specific concentration ranges of 13-40% aromatics, 4-33% olefins, and 45-68% saturates.
⚡ Can this method be applied to samples from coal or shale?
No, the applicability of the test method to non-petroleum fossil fuels (coal, shale, tar sands) has not been determined, and the existing precision may not apply.