Terpenes, HPLC analysis

Microbial reduction of prochiral cyclopentane- and cyclohexane-1,3-diones was extensively studied during the 1960 s in connection with steroid total synthesis. Kieslich, Djerassi, and their coworkers reported the reduction of 2,2-dimethylcyclohexane-l,3-dione with Kloeokera magna ATCC 20109, and obtained (S)-3-hydroxy-2,2-dimethylcyclohexanone. We found that the reduction of the 1,3-diketone can also be effected with conventional baker s yeast, and secured the hydroxy ketone of 98-99% ee as determined by an HPLC analysis of the corresponding (S)-a-methoxy-a-trifluoromethylphenylacetate (MTPA ester).(S)-3-Hydroxy-2,2-dimethy1cyc1ohexanone has been proved to be a versatile chiral non-racemic building block in terpene synthesis as shown in Figure 1. 

High-performance liquid chromatography was the first method of choice for the nonvolatile terpenes as terpene trilactones. The analysis is performed by RP-HPLC on Cig with isocratic development either in methanol-water or methanol-water-THF. Detection can be carried out by UV (taking into consideration poor UV absorption of the compounds), Rl, ELSD, or MS. 

Air samples were collected on Tenax TA (60-80 mesh) (0.5-1.0 1 total volume at a flow rate of 50 ml/min). The analysis of Tenax tubes was carried out using a GC/ MS-system (Hewlett-Packard 6890) or a GC/FID-system (Hewlett-Packard 5890) with a 25-m HP-5 column, each equipped with a thermal desorber - cold trap injector (Perkin Elmer ATD 400). Identification of the compounds was based on a PBM library search. Moreover, mass spectra and retention data were compared with those of reference compounds. The monoterpenes and sesquiterpenes were sampled on active charcoal (NIOSH standard, SKC 226-01, 60-80 1 total volume at a flow rate of 0.5 1/min). The terpenes were extracted by use of carbon disulfide under constant shaking for 1 h and analyzed via GC/FID. Aldehydes were trapped on filter cartridges coated with dini-trophenylhydrazine (DNPH) (Macherey Nagel). The dinitrophenylhydrazone derivatives were extracted with acetonitrile and analyzed via HPLC/UV. 

Mondello, L., K. D. Bartle, G. Dugo, and P. Dugo, 1994a. Automated HPLC-HRGC A powerful method for essential oil analysis Part III. TUiphatic and terpene aldehydes of orange oil. 

A powerful method for essential oils analysis. Part V. Identi cation of terpene hydrocarbons of bergamot, lemon, mandarin, sweet orange, bitter orange, grapefruit, clementine and Mexican lime oils by coupled HPLC-HRGC-MS(ITD). 10 33. 

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