Rapid quantitative analysis of suspected fragrance allergens in between commercial essential oils and using attenuated total reflectance–infrared (ATR–IR) spectroscopy

We studied the suspected fragrance allergens citral, geraniol, cinnamyl alcohol, α-amyl cinnamaldehyde and 4-allylbenzenes (eugenol, methyl eugenol, acetyl eugenol, estragole, safrole and myristicin), as well as 4-propenylbenzenes (isoeugenol, α-asarone and trans-anethole) using two complementary, fast and non-destructive methods: attenuated total reflectance–infrared (ATR–IR) and Raman spectroscopy. We investigated a hierarchical cluster analysis based on the ATR–IR data. The gas chromatography–mass spectrometry (GC–MS) data of nutmeg, ylang, sandalwood, basil, ginger, thyme and fennel essential oils correlates very well with the results of Ward’s algorithm. We also used ATR–IR spectroscopy as a rapid method for quantitative analysis of suspected fragrance allergens in commercial essential oils. The method was based on ATR–IR utilizing partial least squares regression. The calibrations were modeled in the characteristic region (citral 1193–1194 cm−1, geraniol 1375–1378 cm−1, cinnamyl alcohol 732–734 cm−1, α-amyl cinnamaldehyde 1623–1624 cm−1, estragole 1583–1584 cm−1, eugenol 792–795 cm−1, methyl eugenol 804–807 cm−1, acetyl eugenol 1603–1604 cm−1, isoeugenol 959–963 cm−1, trans-anethole 1282–1283 cm−1, α-asarone 1401–1402 cm−1, safrole 1441–1443 cm−1) for suspected fragrance allergens.