ASTM D5845-21 PDF

Overview

ASTM D5845-21 is the standard test method for the determination of MTBE (methyl tert-butyl ether), ETBE (ethyl tert-butyl ether), TAME (tert-amyl methyl ether), DIPE (diisopropyl ether), methanol, ethanol, and tert-butanol in gasoline by infrared spectroscopy. Developed by ASTM International, this standard method is widely used in fuel quality assurance where rapid, reliable analysis of oxygenates is essential. With increasing emphasis on lower emissions and improved fuel performance, the standard provides a practical tool for refineries and testing laboratories.

Key Topics

• Oxygenated Compounds in Gasoline: Alcohols and ethers, such as methanol, ethanol, MTBE, ETBE, TAME, and DIPE, are commonly blended into gasoline to enhance octane ratings and meet regulatory requirements for reduced emissions.

• Infrared Spectroscopy: The method measures characteristic absorbances in the infrared spectrum for each oxygenate, enabling simultaneous quantification without requiring extensive sample preparation.

• Applicable Concentration Ranges:

  • Methanol: 1.7% to 5.5% by mass
  • Ethanol: 1.5% to 10% by mass
  • Tert-butanol: 1.6% to 12% by mass
  • DIPE: 1.2% to 17% by mass
  • MTBE: 2.0% to 16.4% by mass
  • ETBE: 2.0% to 18.5% by mass
  • TAME: 1.5% to 18.5% by mass

• Calibration and Quality Control: Uses multivariate calibration models (as per ASTM D8321), with daily checks using quality control standards to ensure instrument performance and analytical accuracy.

• Precision and Limitations: The method offers good repeatability and reproducibility for its intended range. However, it is not suitable for regulatory compliance testing and may show false positives with certain base gasolines.

Applications

• Fuel Quality Control: ASTM D5845-21 enables gasoline producers and laboratories to monitor and control the concentration of oxygenated compounds rapidly. This is crucial in optimizing blending processes, adjusting formulations, and maintaining commercial fuel specifications.

• Operational Efficiency: Compared to traditional gas chromatography, the infrared spectroscopy approach is faster, more portable, and less expensive, making it ideal for in-plant or field analysis where timely decisions are required.

• Environmental Compliance and Performance: While the standard is not intended for direct federal regulatory compliance, it supports internal monitoring for reformulated gasoline programs, assisting in the production of cleaner-burning fuels and ensuring consistent product performance.

• Research and Development: The method’s straightforward analysis lends itself well to process development, bench testing, and evaluating new gasoline formulations containing various oxygenate blends.

Related Standards

Several ASTM standards and international methods are referenced or used alongside ASTM D5845-21, including:

• ASTM D4052: Density, Relative Density, and API Gravity of Liquids by Digital Density Meter
• ASTM D4057: Manual Sampling of Petroleum and Petroleum Products
• ASTM D4307: Preparation of Liquid Blends for Use as Analytical Standards
• ASTM D4815: Determination of MTBE, ETBE, TAME, DIPE, tert-Amyl Alcohol, and C1 to C4 Alcohols in Gasoline by Gas Chromatography
• ASTM D8321: Development and Validation of Multivariate Analyses for Use in Predicting Properties of Petroleum Products based on Spectroscopic Measurements
• ASTM D5599: Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame Ionization Detection

These related standards help ensure the accuracy, reliability, and consistency of oxygenate determinations in fuel quality control processes.

Keywords: ASTM D5845-21, oxygenates, MTBE, ETBE, TAME, DIPE, methanol, ethanol, tert-butanol, gasoline, infrared spectroscopy, fuel analysis, oxygenated fuels, petroleum, fuel quality control, ASTM standards.