Enantio-IRMS

Fig, 6,45 Enantio-IRMS analysis of linalool from coriander seed oil, self prepared (from ref [106])... 

On-line coupling of enantio cGC with IRMS (enantio cGC-IRMS) is one of the latest developments in originspecific analysis of flavouring and fragrance compounds. Enantio-IRMS detects enantiomers of the same source with identical 5 C levels. As outlined in Fig. 6.45, linalool from Coriander oil is detected as an R(20%) S(80%) enantiomeric ratio with identical isotope levels of the enantiomers. 

Enantio-IRMS also offers a direct method to detect conclusively a blend of enantio-pure chiral flavour compounds with synthetic racemates. An origin-specific enantiomeric ratio may be imitated but not yet detectable, neither by enantioselective analysis nor by IRMS-measurements. However, in the case of enantio-IRMS a simulated origin-specific enantiomeric distribution is proved by different 5 C-levels of the detected enantiomers. 

In Fig. 6.46 the experiments to reveal the origin of linalool from a commercially available spike oil are compared [107]. While enantioselective analysis detects the R(80%) S(20%) enantiomeric ratio, indicating a blend with synthetic racemate, the amount of synthetic racemate caimot be calculated, owing to a conceivable partial racemization of linalool during the processing of Lavandula oils. By means of enantio-IRMS investigation the blend of linalool from different origin is proved [R(-26.1 S(-30.67 J], whereas simple IRMS-analysis [R-i-S(-27.07g )] even sim-... 

Fig. 6.46 cGC-lRMS (A), enantioselective (B) and enantio-IRMS measurements (C) from an adulterdated spike oil (from ref [107])... 

Enantio-cGC, however, fails in the case of non-chiral compounds, such as 1,8-cineol. In this special case 1,8-cineol may be attributed to high-level Melaleuca varieties or to the fraudulent addition of Eucalyptus oil. In order to get reliable results, enantio-MDGC-MS analysis and/or IRMS measurements (as far as possible) are necessary. 

Sewenig S, Bullinger D, Hener U, Mosandl A (2005) Comprehensive authentication of (E)-a(/ )-ionone from raspberries, using constant flow MDGC-C/P-IRMS and enantio-MDGC/... 

Presently, online cGC-IRMS determination of 5 C and 5 H values of flavour compounds are established [107. 118-123] and, further on, 5 0 measurements using online cGC-IRMS procedures will be available. Finally, enantio-MDGC combined with multielement- and multicomponent IRMS methods will open the door to comprehensive authenticity assessment of natural flavour and fragrance compounds in the near future. 

---