Chiral Separations in GC 
                                   Outline 
     • Introduction
     • Theory
     • Advantages and Disadvantages
     • Applications 
     • Conclusions 
     • References
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                          Chiral Separations in GC 
                                  Introduction: 
      • One of the limitations of conventional GC
         –Cannot be used to separate enantiomers.
         –Enantiomers are nonsuperimposable mirror-image molecules. 
         –Since they have identical properties, they elute at the same time in 
           non-chiral GC.
      • However diastereomers can be separated using 
        chromatography:
         –Different chromatographic properties 
         –Different retention times
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                          Chiral Separations in GC 
                                   Introduction: 
      • Chiral separations in GC can be achieved via:
         –Using a derivatization procedure with a chiral auxiliary 
         –Using mobile phase additive
          to form diastereomer complexes which then separated on an achiral 
           stationary phase. 
         –Using a non-racemic chiral stationary phase (CSP)
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                              Chiral Separations in GC 
                                        Introduction: 
      •  In the late 1960s, chiral separation in GC was a challenging problem among 
         scientists. 
      •  In 1967, Prof. E. Gil-Av was successfully demonstrated chiral separation for L- and 
         D-amino acid esters with lauryl ester of N-trifluoroacetyl-L-isoleucine  as CSP. 
      •   In 1977, the first polysiloxane bonded CSP, Chirasil-VAL (thermal stability > 
         200⁰C) was developed by H. Frank, G. Nicholson and E. Bayer.
      •  In 1987, the first capillary column coated with cyclodextrins was invented by Prof. 
         W. A. Konig in cooperation with Macherey-Nagel. 
      •  In the early of 1980s, the successful separations of o-, m-, p-xylenes and 
         ethylbenzene on a cyclodextrins CSP were published. 
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                       Chiral Separations in GC 
                                   Theory:
     The main purpose of chiral separations is to determine the precise 
     enantiomeric compositions or enantiomeric excess: 
                           % ee = 100(R-S)/(R+S) 
     with R= major enantiomer
                 S= minor enantiomer of chiral analytes
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