Development of a Thin Layer Chromatography Method for the Separation of Enantiomers Using Chiral Mobile Phase Additives

• NCJ Number: 240685
• Author(s): Robyn L. Larson; Kelly A. Howerter; Jacob L. Easter
• Date Published: December 2012
• Length: 55 pages
• Grant Number(s): 2008-DN-BX-K140
• Agencies: NIJ-Sponsored
• Publication Type: Report (Study/Research)

Annotation

This project's objective was to develop an inexpensive and simple method for enantiomer determinations in controlled substances as an alternative to using mixed crystal test method, polarimetry, or more expensive instrumental methods.

Abstract

Currently, the resolution of enantiomeric controlled substances is a problem for forensic chemists, since one enantiomer is usually controlled while the other enantiomer is not. The current project evaluated the use of chiral mobile-phase additives (CMAs) in thin layer chromatography (TLC) as an alternative method of enantiomer determination. Although TLC is not a novel technique its use as a method for resolving stereoisomeric controlled substances has not been widely examined. The research found that vancomycin was the most successful chiral mobile phase additive for producing enantiomeric separation, but inconsistently. Visualization of methorphan was troublesome because the multiple functional groups on vancomycin react with iodoplatinate, ceric sulfate, and the I2 vapors. Consequently, the concentration of vancomycin could not exceed 0.05M. The successful vancomycin mobile phase was always slightly opaque or cloudy. Each time the mobile phase was made, the opaqueness seemed to vary slightly and the separation seemed dependent on the appearance of the mobile phase. Even though the solution was cloudy, vancomycin did not come out of solution as a white precipitate as was observed with other mobile phases. Further research that uses vancomycin or another macrocyclic antibiotic for TLC separations may be useful. Although a suitable TLC method was not developed in this research, a more efficient, cost-effective method for differentiating stereoisomers may aid in coping with the increasing backlog in many laboratories by reducing the time required for such determinations. 14 tables and 17 references