title: Simultaneous estimation of levodopa and carbidopa by RP-HPLC using a fluorescence detector: its application to a pharmaceutical dosage form.
abstract: A reverse-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the simultaneous estimation of levodopa and carbidopa in bulk and pharmaceutical formulations. Chromatographic separation was achieved by using a C18 reverse-phase column and a mixture of an aqueous phase (10 mM potassium dihydrogen phosphate buffer, pH4.0) and methanol (90:10 v/v) as the mobile phase. Quantitative analysis of levodopa and carbidopa was performed using a fluorescence detector at an excitation wavelength of 280 nm and an emission wavelength of 310 nm. The method was linear between 5 and 500 ng/mL for both levodopa and carbidopa. The detection limits for levodopa and carbidopa were 0.30 and 0.60 ng/mL, respectively, whereas the quantitation limit was 0.80 ng/mL for levodopa and 1.2 ng/mL for carbidopa. The method demonstrated good and consistent recoveries (99.63-100.80% for levodopa and 98.97-100.94% for carbidopa) with low interday and intraday relative standard deviation. The validated method was successfully applied to quantify levodopa and carbidopa simultaneously in a pharmaceutical formulation. The method was found to be precise, sensitive and accurate for the simultaneous determination levodopa and carbidopa in bulk and pharmaceutical formulations.
authors.affiliation: Department of Pharmacy, Birla Institute of Technology and Science, Pilani, India.
authors.forename: Prashant P
authors.initials: PP
authors.lastname: Raut
authors.forename: Shrikant Y
authors.initials: SY
authors.lastname: Charde
mesh_terms: D002230:Carbidopa / Q000032:analysis*; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D007980:Levodopa / Q000032:analysis*; D008968:Molecular Conformation; D013050:Spectrometry, Fluorescence
chemical_list: D007980:Levodopa; D002230:Carbidopa
keywords: HPLC/fluorescence detection; carbidopa; design of experimentation; levodopa; robustness