Make Your Unknowns, “Known” with High Resolution Mass Spectrometry

The combination of high performance mass spectrometry and comprehensive two-dimensional GC definitively takes unknown components and unambiguously identifies an important odor component in a perfume sample.

GC–MS has been an important tool in the perfume industry for decades, providing robust characterization of samples for quality control, new product development, and even competitive analysis. These capabilities can be extended with the addition of a complementary separation dimension with GC×GC, and with a high performance mass spectrometer to better separate and identify components in a perfume sample.

Experimental Conditions

Samples were diluted and injected for analysis on three instrument platforms; Pegasus® HT GC-TOFMS, Pegasus 4D GC×GC-TOFMS, and Pegasus GC-HRT 4D.

Results

Figure 1 demonstrates improved confidence in the identification of an important odor analyte by improving chromatographic separation and adding accurate mass detection with GC×GC-HR-TOFMS. The analyte was found (through first dimension retention and spectral consistency) and compared in GC-TOFMS, GC×GC-TOFMS, and GC×GC-HR-TOFMS data. The spectrum for iso-eugenol in the GC-TOFMS experiment matched very poorly to the library standard at less than 50% similarity. Without additional information this would likely be considered an unknown. When analyzed by GC×GC-TOFMS, the similarity to the library spectrum improved to over 80%, which was primarily related to the improved chromatographic separation. There are several m/z in the low mass region (<100 m/z) that are observed in the GC-TOFMS spectrum, and are absent in the GC×GC-TOFMS spectrum, that were attributed to coeluting analytes in the first dimension separation which were chromatographically separated in the second dimension. GC×GC provided both a cleaner iso-eugenol spectrum and the ability to detect the coeluting analytes. Confirmation of identification is often pursued with the analysis of standards, which is not always possible due to availability or cost restrictions. The same level of confidence can be attained by pairing a high resolution mass spectrometer with the GC×GC separation. The GC×GC-HR-TOFMS spectrum improved the confidence with a library similarity of over 80%, mass accuracy of the molecular ion (RDBE = 5) of < 1 ppm, and mass accuracy of fragments across the mass range of less than 1 ppm, on average.


Figure 1: A comparison of spectra obtained from Pegasus HT, Pegasus 4D, and the Pegasus GC-HRT 4D for a particular component in a perfume sample.

Conclusion

High performance mass spectrometry and comprehensive GC (GC×GC) provides improved confidence of the presence of iso-eugenol, a characteristic spicy odor component in a perfume sample that was difficult to identify with GC-TOFMS.

LECO Corporation
3000 Lakeview Avenue, St. Joseph, MI 49085
tel. (269) 985-5496, fax (269) 982-8977
Website: www.leco.com

 

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