Answer 1

HPLC is in fact the best known method for distinguishing enantiomers from one another within a racemic mixture. This is by virtue of the fact that the test is around three times more sensitive than gas chromatography-mass spectrometry (GC-MS). While nuclear magnetic resonance and infrared spectroscopy can provide specific structural information for the identification of closely related compounds, these methods are of little value in the analysis of drugs in biological samples since they require a relatively large amount of sample of high purity.