Follow your nose ‐ Traveling the world of odorants in new cars

Abstract

Volatile organic compounds of the vehicle interior are well investigated, but only limited information is available on the odorants of the passenger cabin. To close this gap, we aimed at specifically elucidating the odor, as a general proof of principle, of two new cars with different seat upholstery in a controlled environment using a targeted odorant analysis. In a first step, odor profiles were evaluated by a descriptive sensory analysis. Then, potent odorants of the passenger cabins were characterized by gas chromatography‐olfactometry and ranked according to their odor potency via odor extract dilution analysis. Using this approach, 41 potent odorants were detected, and 39 odorants were successfully identified by two‐dimensional gas chromatography‐mass spectrometry/olfactometry. In a third step, important odorants of the vehicle interior were quantified by means of internal standard addition. The most dominant odorants could be assigned to several specific substance classes comprising esters, saturated and unsaturated aldehydes, unsaturated ketones, rose ketones, phenolic and benzene derivatives, and pyrazines, occurring in a concentration range between 0.05 and 219 ng/L in air. Of these potent odorants, the aldehydes 2‐butylhept‐2‐enal, 2‐propyloct‐2‐enal, and (Z)‐2‐butyloct‐2‐enal are reported here for the first time as odorants in the environment of a passenger cabin.

Smells like new car or rather like an old carriage? ‐ Resolution of the decay behavior of odorants in vehicle cabins during usage

“…Emissions in the passenger cabin have commonly been reported to mainly contain apolar aliphatic and aromatic hydrocarbons as well as semi‐polar alcohols and carbonyl compounds, albeit the latter being present in lower concentrations 18,19 . However, the odorants of the two investigated vehicles that had been detected in our previous study can be classified as being predominantly semi‐polar 11 . As a consequence, divergences in decrease of the respective substance classes as a result of the polarity of the compounds are likely and might be proposed to result in a different fogging behavior.…”

“…The panelist exhibited a higher odor threshold for benzothiazole after an illness between the second and third measurement; therefore, the values beginning from the third measurement cannot be used for interpretation. OD factors identified in the distillate of the sample obtained directly after vehicle delivery were previously published 11 …”

“…To remove non‐volatile constituents of the extract, as dust and air‐borne particles, which were present after elution, the solvent‐assisted flavor evaporation (SAFE) technique was applied 14 . The subsequent distillation steps of the extract and the instrumental setup for the identification of the odorants, the gas chromatography‐olfactometry (GC‐O) and two‐dimensional gas chromatography‐mass spectrometry/olfactometry (2D‐GC‐MS/O) systems are described in detail in our previous studies 10,11 . Identification of odorants was achieved by comparing the respective odor qualities (O), retention indices (RI) on two capillaries with different polarities (DB‐FFAP and DB‐5), and the mass spectra (MS) with the data of the respective reference compounds (RC).…”

“…34,35 In our previous study, we assigned hexanal, (E)-2-nonenal, octanal and vanillin as odorants being potentially responsible for the wood-like odor impression, and 1-hexen-3-one and 1-octen-3-one as potential contributors to the plastic-like odor impression. 11 These compounds have been responsible for the characteristic odor in reconstitution experiments in wood and artificial leather, respectively. 36,37 The decay behavior of 1-hexen-3-one and 1-octen-3-one matched very well with the sensory results after the two measurements of vehicle 2, supporting the assumption that these two odorants are likely contributors to the plastic-like odor impression.…”

“…Thereby, we identified the odor-active compounds by linking the chemical structures of the relevant odorants to the odor impressions obtained by a descriptive odor analysis, and we discussed the possible sources and formation pathways. 11 However, the typical new car smell is not only perceived directly after delivery. Vehicles maintain their typical odors for quite a period of time even though the gas composition of the vehicle interior changes during use due to elevated temperatures or ventilation.…”