S. Fanali et al., Quality control of benserazide-levodopa and carbidopa-levodopa tablets by capillary zone electrophoresis, ELECTROPHOR, 21(12), 2000, pp. 2432-2437
In modern practice, the treatment of Parkinson's disease and syndrome is ca
rried out using pharmaceutical formulations containing a combination of lev
odopa and a decarboxylation inhibitor (carbidopa or benserazide). Two pharm
aceutical formulations were quantified by capillary zone electrophoresis us
ing two procedures which differed only in the kind of background electrolyt
e used. One procedure used a 25 mM phosphate buffer, pH 2.5, while the seco
nd one used a 25 mM berate buffer, pH 8.5. The electrophoretic analysis was
carried out using an uncoated fused- silica capillary, a separation voltag
e of 20 kV with currents typically less than 60 mu A, and spectrophotometri
c detection at 205 nm. Calibration curves were performed for levodopa (conc
entration range 1-100 mu g/mL), for carbidopa and benserazide (1-50 mu g/mL
), and the plots of the peak area versus concentration were found to be lin
ear with a correlation coefficient better than 0.9990. Satisfactory results
were obtained when commercial tablets were analyzed in terms of accuracy (
98-102%), repeatability (0.6-2.0%), and intermediate precision (1.1-2.6%).