Chiral Separation of Penicillamine Enantiomers by Capillary Electrophoresis and Its Application

This study presents a novel method for the chiral separation of penicillamine enantiomers. The penicillamine enantiomers were derivatized with 1-chloro-2,4-dinitrobenze (CDNB) and separated by capillary electrophoresis. The β-cyclodextrin (β-CD), methyl-β-cyclodextrin (M-β-CD), hydroxypropyl-β-CD (HP-β-CD), and sulfated-β-cyclodextrin (S-β-CD) as chiral selectors were examined for the enantiomeric separation of penicillamine. In addition to the concentration of chiral selectors, other experimental factors, such as concentration of borate buffer, pH of electrolyte, and applied voltage, were also optimized. Optimal separation was obtained with a running buffer consisting of 50 mM borate solution (pH 9.5) containing 25 mM S-β-CD, with applied voltage of 20 kV and capillary temperature of 20°C. Detection was followed by direct UV absorptiometric measurements at 202 nm. The derivatives of penicillamine enantiomers were resolved completely in 14 minutes, giving a resolution that reached up to 3.7. The linear range, the recovery, and the repeatability of L-penicillamine in the presence of large amount of D-penicillamine were tested and a satisfactory result was obtained. The method developed was used for the optical purity analysis of the D-penicillamine drug and allowed for the determination of 0.3% L-penicillamine in D-penicillamine with apparent peak identification.