Odor characterization of a cavity preservation using emission test chambers by different sensory evaluation methods and sampling concepts for instrumental analysis

Abstract

The odor of an automotive cavity preservation has been shown to be perceivable in the vehicle interior due to negative pressure forces in the passenger cabin during driving. To obtain deeper insights into its odor composition, this study aimed at characterizing the odorants by means of emission test chamber measurements adapted from ISO 12219–4, a method for the determination of the emissions of volatile organic compounds from vehicle interior parts and materials. The odor of the sample was evaluated by different procedures: descriptive odor analysis of the chamber headspace was performed and compared with the odor profile of the cavity preservation by sample presentation in a glass vessel as in VDA 270, a sensory evaluation method applied by the automotive industry. Both approaches revealed similar odor profiles with the attributes waxy, rancid, and fruity/peach-like, whereas in the odor bag the odor attribute pungent was not perceived as a result of the dynamic air exchange in the chamber. For a combined sensory instrumental analysis, chamber headspace was sampled with the aim to investigate the odorants in the form of a liquid extract. Three different sampling procedures were compared in this respect: (i) adsorption of chamber headspace on Tenax® TA and subsequent elution of the adsorbed emissions with a solvent; (ii) adsorption of chamber headspace on Carbotrap® 300 followed by the elution step according to (i); and (iii) absorption of chamber headspace in a solvent. All sampling methods succeeded in the identification of the substance groups of carboxylic acids, γ-lactones, oxygenated aromatic compounds and esters although the sample preparation differed considerably. The results provide a solid foundation for future investigations on the odor of other vehicle assemblies by means of emission test chambers or whole vehicle interiors.

Keywords

• Cavity preservation
• Emission test chamber
• Gas chromatography olfactometry
• Descriptive sensory analysis
• Adsorption
• Absorption