Comparison of HPLC Separation of Phenylalanine Enantiomers on Different Types of Chiral Stationary Phases

Abstract

HPLC separation of phenylalanine by using chiral stationary phases (CSPs) with chiral selectors β-cyclodextrin, isopropylcarbamate cyclofructan 6, teicoplanin, and ristocetin were studied. The effects of mobile phase composition and column temperature from 0 to 30 °C on the retention and resolution of enantiomers were investigated. β-cyclodextrin and isopropylcarbamate cyclofructan 6 CSPs showed chiral recognition in normal phase separation mode. The sufficient enantioseparations (resolution values 1.59 and 2.75) were reached using teicoplanin and ristocetin-based stationary phases at 23 °C in reversed-phase mode with mobile phases consist of acetonitrile and water at ratios 75/25 and 60/40 (v/v), respectively. Chiral HPLC system coupled with circular dichroism and polarimetry detector could be used to determine enantiomeric elution order. The optimized and validated HPLC-UV method with teicoplanin-based chiral stationary phase was applied for determination of phenylalanine in real samples. Both of the enantiomeric forms were detected in samples of dietary supplements and L-phenylalanine in samples of energy drinks. Obtained recoveries were higher than 82% with an RSD less than 10%. The HPLC method showed good linearity (correlation coefficients > 0.998) in concentration range 0.1–500 μg mL−1. The limit of detection was 0.1 μg mL−1 for both enantiomers.