Determination of Enantiomeric Composition of Substituted Tetrahydroisoquinolines Based on Derivatization with Menthyl Chloroformate

A method for the analysis of the optical purity of a series of chiral substituted tetrahydroisoquinolines (THIQs) was developed. The method is based on pre-column derivatization of the analytes with the derivatization reagent (–)-(1R)-menthyl chloroformate. The derivatization reaction selectively gives diastereomeric carbamates that are resolvable on an achiral non-polar GC column. The developed technique covers variously substituted THIQs, which differ significantly in volatility, steric and electronic properties. In all cases, the resolution factors (R) exceeded the value of 1.5. The method represents a robust way of analysis of mixtures of THIQs, which are often present in various matrixes such as body fluids, tissues and reaction mixtures.