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D5769-22 – Standard Test Method Technical Guide
📏 Scope and Applicability of D5769-22
This standard test method outlines the determination of benzene, toluene, specific individual aromatic compounds, and total aromatics in finished motor gasolines using Gas Chromatography/Mass Spectrometry (GC/MS). The method is validated for finished gasoline blends, including those containing oxygenated additives, and reports results as volume percent (% vol).
Precision data for this method was generated through a comprehensive Interlaboratory Study (ILS) compliant with Practice D6300. The concentration ranges covered by the ILS are strictly defined.
| 🟦 Analyte | 📏 ILS Low Concentration (% vol.) | 📏 ILS High Concentration (% vol.) | 🎯 Reporting Precision |
|---|---|---|---|
| Benzene | 0.09 | 4.00 | ± 0.01 % |
| Toluene | 1.0 | 13.0 | ± 0.1 % |
| Total Aromatics (C6 to C12) | 10.0 | 42.0 | ± 0.1 % |
⚠️ Matrix Limitation: The ILS did not evaluate the method for individual refinery process streams such as reformates or fluid catalytic cracked naphthas. Users applying this method to these specific blending components should do so with caution regarding published precision.
⚙️ Test Method Principles and Referenced Standards
The analytical technique relies on Gas Chromatography coupled with Mass Spectrometry (GC/MS) for separation and quantification. Successful implementation requires adherence to several key ASTM standard practices. Sample handling must follow Practice D4057, and the preparation of liquid standards should follow Practice D4307. Density measurements for volume percent calculations are referenced against Test Methods D4052 or D1298.
In addition, the standard provides a significant between-method bias section for benzene. It assesses the agreement between D5769 and the widely used Test Method D3606 (Gas Chromatography for Benzene and Toluene in Spark Ignition Fuels). This assessment, governed by Practice D6708, allows D5769 to serve as an alternative to D3606 for spark-ignition engine fuel benzene reporting within a specific range.
💡 Method Correlation: The D6708 correlation between D5769 and D3606 is applicable for blended fuels with benzene results in the concentration range of 0.05 % to 2.50 % by volume as measured by Test Method D5769.
📊 Reporting and Key Measured Properties
The primary output of this test method is the concentration of benzene, toluene, and total aromatics in the finished gasoline. Results are expressed as liquid volume percent. Specific reporting precision requirements are mandated: benzene results are reported to the nearest 0.01 %, while toluene and total aromatic values are reported to the nearest 0.1 %.
Compliance with the precision and bias statements is based on the D6300 guidelines. The standard is under the jurisdiction of ASTM Subcommittee D02.04.0M on Mass Spectrometry and adheres to the principles of terminology found in D4175 and E355.
❓ Frequently Asked Questions
🔍 Are oxygenated gasolines within the scope of D5769-22?
Yes, the scope explicitly states that the method covers finished motor gasolines containing oxygenated blending components.
💡 What density test methods are referenced for calculating volume percent?
Test Method D4052 (Digital Density Meter) and Test Method D1298 (Hydrometer Method) are the referenced standards for density, relative density, or API gravity determination.
⚡ Is D5769 directly applicable to reformates or FCC naphthas?
The ILS data and precision statements do not cover these specific individual process streams. D5769 was validated for finished motor gasoline blends.
📌 What is the reporting precision for benzene and total aromatics?
Benzene is reported to the nearest 0.01 % by liquid volume. Total aromatics, along with toluene, are reported to the nearest 0.1 % by liquid volume.