Determination of the enantiomeric purity of amphetamine after derivatization with Sanger’s reagent (2,4-dinitrofluorobenzene [DNFB]) by simultaneous dual circular dichroism and ultraviolet spectroscopy

Abstract

A new analytical procedure has been developed for the determination of the enantiomeric purity of amphetamine samples. It is based on the derivatization of amphetamine with 2,4-dinitrofluorobenzene and a subsequent measurement of the anisotropy factor by dual (CD/UV) spectroscopy. This factor depends on the enantiomeric composition and does not depend on the concentration, a feature that eliminates the systematic errors caused by the sample preparations such as dilution, weighing, etc. The main advantage of the approach is the fact that the new synthetized derivative can be measured in the visible wavelength region with significantly better sensitivity than the underivatized amphetamine. The applicability of the procedure is demonstrated by results obtained by analysis of model materials containing amphetamine enantiomers at different ratios.