Chiral thin-layer chromatography

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File:Photo of a TLC plate Baclofen.tif Baclofen (left). Pure (S)-enantiomer (right).{{cite journal |last1=Singh|first1=Manisha|last2=Malik|first2=Poonam|author3-link=Ravi Bhushan |last3=Bhushan|first3=Ravi|date=2016 |title= Resolution of enantiomers of (RS)-baclofen by ligand exchange thin layer chromatography|journal=Journal of Chromatographic Science |volume= 54|issue=5 |pages=842–846 |doi=10.1093/chromsci/bmw014|pmid=26896346 |pmc=4890457 |doi-access=free}}]]

Chiral thin-layer chromatography is a variant of liquid chromatography that is employed for the separation of enantiomers. It is necessary to use either

• a chiral stationary phase or
• a chiral additive in the mobile phase.

The chiral stationary phase can be prepared by mixing chirally pure reagents such as L-amino acid, or brucine, or a chiral ligand exchange reagent with silica gel slurry,{{cite journal |last1=Bhushan|first1=Ravi|last2=Martens|first2=Jürgen|date=1997|title= Direct Resolution of Enantiomers by Impregnated TLC |journal= Biomedical Chromatography |volume= 11|issue=5 |pages=280–285 |doi= 10.1002/(SICI)1099-0801(199709)11:5<280::AID-BMC697>3.0.CO;2-U|pmid=9376709 }}{{cite journal |last1= Sajewicz|first1= Mieczysław|last2= Piętka |first2= Robert | last3= Kowalska |first3= Teresa |date=2004|title= Chiral Separation of (S)-(+)- and (R)-(−)-Ibuprofen by Thin-Layer Chromatography. An Improved Analytical Procedure |journal= Journal of Planar Chromatography: Modern TLC |volume=17 |issue=2|pages=173–176|doi=10.1556/JPC.17.2004.3.3|s2cid= 94295876}} or by impregnation of the TLC plate in the solution of a chiral reagent.{{cite journal |date=1984|title= Thin-Layer Chromatographic Enantiomeric Resolution via Ligand Exchange|author1=Günther, Kurt |author2=Martens, Jürgen |author3=Schickedanz, Maren |journal= Angewandte Chemie International Edition in English |volume= 23 |issue= 7|pages= 506 |doi= 10.1002/anie.198405061}}

The principle can also be applied to chemically modify the stationary phase before making the plate via bonding of the chiral moieties of interest to the reactive groups of the layer material.{{cite journal|last1= Ala|first1= Alak|last2= Armstrong|first2= Daniel W|date=1986|title= Thin-layer Chromatographic Separation of Optical, Geometrical, and Structural Isomers|journal= Analytical Chemistry|volume= 58|issue= 3|pages= 582–584|doi= 10.1021/ac00294a020}}{{cite journal |last1= Del Bubba |first1= Massimo |last2= Checchini |first2= Leonardo | last3= Lepri |first3= Luciano|date=2012|title= Thin-layer chromatography enantioseparations on chiral stationary phases: a review|journal= Analytical and Bioanalytical Chemistry |volume=405|issue= 2–3 |pages=533–554| doi =10.1007/s00216-012-6514-5|pmid= 23161065 |s2cid= 22147187 }}