Enantiomeric composition of abused amine drugs: chromatographic methods of analysis and data interpretation.

Enantiomers are pairs of nonsuperimposable mirror-image compounds, typically include one or more asymmetric (chiral) carbons (carbon bonded to four different groups). The two individual components of an enantiomer-pair have identical chemical and physical properties, differing only in the way they react with other chiral compounds and the direction in which they rotate plane-polarized light, and therefore, cannot be resolved by conventional chromatographic methodologies. The configuration of the groups bonded to the chiral atom is designated as S or R, while D/+ and L/ are used to describe the direction in which a polarized light is rotated by the molecule. A left-handed or levorotatory (L/ ) compound rotates polarized light to the left while a right-handed or dextrorotatory (D/+) compound rotates polarized light to the right. Configuration alone does not predict the light-rotating direction, a full description of a compound often includes designations for the configuration (S/R) and the light-rotating characteristic (D/L or +/ ). When the quantities of two enantiomers in a solution are exactly equal, it becomes optically inactive and is called a racemate.