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D6258-17 – Standard Test Method Technical Guide
🔬 Scope and Applicability
This test method, ASTM D6258-17 (Reapproved 2024), defines the procedure for measuring Solvent Red 164 dye concentration in diesel and burner fuels using visible spectroscopy. It is designed for No. 1 and No. 2 grades per Specifications D396 and D975, and marine grades DMA and DMB per D2069.
The calibration aligns with IRS regulations, requiring tax-exempt diesel fuel to contain Solvent Red 164 at a concentration spectrally equivalent to 3.9 lb of Solvent Red 26 per thousand barrels (11.1 mg/L).
⚙️ Test Method and Derivative Analysis
Sample absorbance is recorded over a specified wavelength range. Derivative analysis software processes the scan to determine dye concentration, effectively mitigating interferences from fuel color variations—from water white to nearly black—and blends with used oils.
This approach ensures accurate quantification by correcting for background absorption, as standardized in ASTM E169 and E275 practices for UV-VIS analysis.
📊 Calibration and Reference Standards
The method relies on calibration standards set to the IRS equivalent concentration. Key parameters are summarized below:
| 🟦 Parameter | 📏 Specification |
|---|---|
| Target Analyte | Solvent Red 164 |
| Reference Dye | Solvent Red 26 |
| Concentration Equivalent | 11.1 mg/L (3.9 lb/1000 bbl) |
| Fuel Grades | No. 1 & 2 Diesel, Marine DMA/DMB |
| Analytical Technique | Visible Spectroscopy with Derivative Software |
Associated ASTM standards include D396, D975, D2069, D3699, D4057, E131, E169, E275, E288, E691, E969, and federal regulation 26 CFR 48.4082-1(b).
✅ Technical Insight: Derivative analysis effectively eliminates baseline shift from fuel coloration, making the method robust for a wide range of diesel fuel samples.
⚠️ Safety Note: Users must establish appropriate health and safety practices as per their organizational guidelines when handling fuel and dye samples.
❓ Frequently Asked Questions
🔍 Why is Solvent Red 164 dye concentration measured?
To verify that tax-exempt diesel fuel meets IRS dyeing requirements, with a concentration spectrally equivalent to 3.9 lb of Solvent Red 26 per 1000 bbl (11.1 mg/L).
💡 Can this method be used for all diesel types?
It is suitable for No. 1 and No. 2 grades in D396 and D975, and for marine fuels DMA and DMB in D2069.
⚡ What technique reduces background interference?
Derivative analysis software processes absorbance scans to correct for natural fuel color variations, which range from water white to nearly black, ensuring accurate dye measurement.
📌 Which ASTM standards are referenced?
Key references include D396, D975, D2069, D3699, D4057, E131, E169, E275, E288, E691, and E969 for instrumentation and practices.