ASTM D7796-21 PDF

Full title and description

Standard Test Method for Analysis of Ethyl tert-Butyl Ether (ETBE) by Gas Chromatography — a procedure using capillary gas chromatography with a methyl‑silicone bonded phase column and flame ionization detection to determine the purity of ETBE and to quantify a range of volatile organic impurities that may be present in ETBE product.

Abstract

This test method (ASTM D7796‑21) describes sampling, chromatographic separation, and quantification procedures for ETBE and common co‑components/impurities (for example C4–C12 olefins, methyl, isopropyl and tert‑butyl alcohols, methyl sec‑butyl and methyl tert‑amyl ethers, acetone, methyl ethyl ketone). The method uses an open‑tubular column (methyl silicone bonded phase) and flame ionization detection; it does not determine water and is not intended for determining ETBE content in finished gasoline.

General information

• Status: Active / Published.
• Publication date: Current edition approved December 1, 2021; published December 2021 (ASTM record also shows 30 November 2021 as the publication record date).
• Publisher: ASTM International (formerly American Society for Testing and Materials).
• ICS / categories: 71.080.60 (Alcohols. Ethers); 75.160.20 (Liquid fuels).
• Edition / version: D7796‑21 (designation indicates 2021 edition). DOI: 10.1520/D7796‑21.
• Number of pages: 7 pages (concise test method).

Scope

The standard covers determination of the purity of ethyl tert‑butyl ether (ETBE) by gas chromatography and provides a procedure to measure impurities such as C4 to C12 olefins, methyl, isopropyl and tert‑butyl alcohols, methyl sec‑butyl and methyl tert‑amyl ethers, acetone, and methyl ethyl ketone. It excludes measurement of water (water must be measured by a separate method such as ASTM D6304) and is not applicable to determining ETBE when present in gasoline; it is also inappropriate for impurities with boiling points above about 180 °C or for species that give little/no FID response.

Key topics and requirements

• Primary analyte: ethyl tert‑butyl ether (ETBE) purity and quantitation.
• Target impurities listed: C4–C12 olefins; methyl, isopropyl, tert‑butyl alcohols; methyl sec‑butyl ether; methyl tert‑amyl ether; acetone; methyl ethyl ketone.
• Instrumentation: capillary (open‑tubular) GC column with methyl‑silicone bonded phase; helium carrier; flame ionization detector (FID).
• Sample preparation and normalization: water must be measured separately (e.g., D6304) and chromatographic results normalized for water content.
• Limitations: not suitable for high‑boiling or FID‑inactive impurities (boiling point ≳180 °C); some co‑elutions may occur.
• Precision and interlaboratory performance: the standard’s precision statement has known limitations and a revision project has been opened to update the precision statement based on a new ILS.

Typical use and users

Used by analytical and quality‑control laboratories at ETBE producers and suppliers, petrochemical QC labs, independent testing laboratories, and regulatory or fuel specification bodies for product valuation, process control, specification compliance, and impurity monitoring. The method is intended for routine determination of ETBE purity and common volatile impurities in manufacturing and quality contexts.

Related standards

References and related documents cited in D7796‑21 include ASTM practices and methods for sampling and preparation (e.g., D4057, D3700), water determination (D6304), gas‑chromatography terminology and detector practice (E355, E594), calculation of response factors (D4626), and product specification D7618 (Specification for ETBE for blending). These referenced documents provide sampling, terminology, calibration, and complementary test procedures.

Keywords

ETBE; ethyl tert‑butyl ether; gas chromatography; GC‑FID; impurities; oxygenate; fuel additive; C4–C12 olefins; methyl ether; alcohols.

FAQ

Q: What is this standard?

A: ASTM D7796‑21 is a standardized gas chromatographic test method for determining the purity of ethyl tert‑butyl ether (ETBE) and quantifying a set of common volatile impurities.

Q: What does it cover?

A: It specifies sample handling notes, GC column and detector approach (methyl‑silicone capillary column with FID), target impurities (C4–C12 olefins, several alcohols and ethers, acetone, MEK), limitations (no water determination; not for ETBE in gasoline; high‑boiling or FID‑inactive species excluded).

Q: Who typically uses it?

A: ETBE manufacturers, petrochemical and fuel testing laboratories, quality and process control analysts, and regulatory/specification bodies concerned with oxygenate purity and impurity profiling.

Q: Is it current or superseded?

A: The current edition is D7796‑21 (approved Dec 1, 2021 and published December 2021). The standard is active; a formal revision work item to update the precision statement was initiated (ASTM WK97898, initiated January 27, 2026), so users should check for amendments or a future revised edition.

Q: Is it part of a series?

A: It is maintained by ASTM Committee D02 (Petroleum Products, Liquid Fuels, and Lubricants), Subcommittee D02.04.0L (Gas Chromatography Methods), and is related to other D02 methods and specifications (for example D7618 for ETBE product specification).

Q: What are the key keywords?

A: ETBE; ethyl tertiary‑butyl ether; gas chromatography; GC‑FID; impurities; oxygenate; fuel additive; C4–C12 olefins.