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

Importancia y uso:

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.

Subcomité:

D22.05

Volúmen:

11.07

Palabras clave:

air pollution; air quality; air sampling; environmental odor; GC-O; MDGC-MS-O; mitigation; multi-dimensional gas chromatography-mass spectrometry-olfactometry; nuisance odor; odorant prioritization; odorant prioritization protocol; olfactometry; OPP; rolling unmasking effect; sensory analysis; simultaneous sensory and chemical analysis; SPME; VOCs; volatile analysis; volatile organic compound;