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Electrophoresis, Vol.33, No.13, 2056-2063, 2012
Separation and determination of chiral composition in penicillamine tablets by capillary electrophoresis in a broad pH range
A chiral capillary electrophoretic method with nearly full pH window was explored for the separation and determination of dl-penicillamine. A facile one-pot labeling technique was coupled in the method for introduction of chromophore and charge groups onto the analytes to facilitate the electromigration and sensitive detection. By using simply a cost-effective neutral beta-cyclodextrin as chiral selector, baseline separation of the dl-penicillamine was achieved from pH 2.0 to over pH 10. Quantification of standard d- and l-penicillamines was demonstrated by taking pH 4.5, 7.4, and 9.7 as the representatives of acidic, neutral, and basic conditions. The working curves were constructed between peak area and concentration, having linear ranges of 8.568.56 x 102 mu g/mL for pH 4.5 and 8.561.71 x 103 mu g/mL for pH 7.4 and 9.7, with correlation coefficients all better than 0.999. The limit of detection (S/N = 3) was 2.58 mu g/mL in acidic and neutral conditions or 1.41 mu g/mL in basic condition. The method was further validated by assaying the commercial penicillamine tablets, applicable to quantification of the effective enantiomer and the trace impurity of l-penicillamine at a content of down to 0.2, 0.6, and 2.0% for pH 9.7, 4.5, and 7.4, respectively. The recovery determined by spiking technique was in a range from 93.1 to 105 %. The method is easily extendable to the analysis of other chiral amines or amino acids.
Keywords:Broad pH window;Chiral separation;Cyclodextrin-assisted capillary electrophoresis;One-pot labeling;Penicillamine