Standard Active Last Updated: Oct 22, 2025 Track Document
ASTM D8623-25

Standard Practice for Environmental Odor Screening for Single, Character-Defining Odorants; Using Gas Chromatography-Mass Spectrometry Olfactometry (GC-MS-O) Analysis and On-Instrument Odor-Matching Confirmation

Standard Practice for Environmental Odor Screening for Single, Character-Defining Odorants; Using Gas Chromatography-Mass Spectrometry Olfactometry (GC-MS-O) Analysis and On-Instrument Odor-Matching Confirmation D8623-25 ASTM|D8623-25|en-US Standard Practice for Environmental Odor Screening for Single, Character-Defining Odorants; Using Gas Chromatography-Mass Spectrometry Olfactometry (GC-MS-O) Analysis and On-Instrument Odor-Matching Confirmation Standard new BOS Vol. 11.07 Committee D22
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Significance and Use

5.1 Historically, environmental odor issues have been assumed to be inherently complex with respect to chemical composition. However, environmental odor issues are often driven by relatively small subsets of odorants from otherwise complex source emissions; in extreme cases, driven by single character-defining compounds. This practice serves as a preliminary screening tool to identify those cases reflecting such relative odor compositional simplicity (Figs. 1 and 2).

5.2 Where such odor compositional simplicity is shown to exist, the challenges to odor monitoring, tracing to source, and mitigation strategy development can be focused and simplified. In contrast, where such preliminary screening fails to reveal existence of such simplicity, the more conventional, comprehensive sensory or instrumental assessment strategies can be undertaken.

5.3 The purpose of this practice is to provide a uniform experimental framework adaptable to the diversity of environmental conditions which may be encountered relative to indoor odor issues (Fig. 2).

5.4 The basis of this screening practice is qualitative rather than quantitative; carrying the limited initial goals of:
(1) confirming/disproving the existence of odor character-defining or character-impacting compounds; (2) GC-MS isolation, electronic detection and, if possible, chemical identification of such detected compound(s); and (3) odor-matching based confirmation of the initial hypothesis emerging from completion of tasks (1) and (2).

5.5 This OPP survey approach is equally applicable to (1) ambient (Fig. 1), (2) workplace, and (3) indoor air environments (Fig. 2). The primary difference between (1) and (3) is the sampling techniques and strategies required specific to each environment.

5.6 These sampling and analytical strategies represent one integrated approach to defining odorant prioritization. There are alternate strategies (for example, packed-tube thermal desorption sampling; multi-dimensional GC based odorant isolation; RI (that is, retention index) based odorant identification; high-capacity SPME sampling devices; and others) which can be integrated into the basic GC-MS-O system to achieve difficult odor challenge resolutions. In addition, alternate analytical strategies, such as odor descriptive analysis, odor dispersion modeling and others may also yield correct and equivalent odorant prioritization results. Therefore, it is understood that such alternate sampling and analytical strategies should be considered acceptable, contingent upon the practitioner’s ability to, ultimately, confirm any resulting odorant prioritization hypotheses through successful odor-matching; either by on-instrument GC-O or by way of synthetic formulation.

Scope

1.1 This practice presents a general strategy for using an analytic, odorant-prioritization-based approach for environmental odor assessment. It is based upon the premise that, while the composition of environmental odors detected by human receptors carries the potential for extreme complexity, simplification (that is, reduction of odorant field to smallest number of odor impactful compounds) typically occurs along the decreasing odor density gradient relative to the source (1-3).2 The odorant prioritization protocol (OPP) is a strategy that encourages initial identification of odor and focuses upon the minimum subset of odorous gases, which are sensory-detectable at the odor frontal boundary.

1.2 The OPP approach to environmental odor assessment is not presented as a replacement or substitute for established, quantitative Dynamic Dilution Olfactometry (DDO) methods (for example, Practices E679 and E1432), which form the current regulatory and enforcement basis for odor air quality impacts. Rather, this OPP approach is a voluntary, qualitative, and complementary assessment strategy for focused odor assessment and monitoring to support odor mitigation strategy development.

1.3 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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Details
Book of Standards Volume: 11.07
Developed by Subcommittee: D22.05
Pages: 15
DOI: 10.1520/D8623-25