Reversed-phase High-performance Liquid Chromatographic Investigation of Levodopa Preparations I: Amino acid Impurities

A reversed-phase high-performance liquid chromatographic procedure with UV detection at 280nm is presented for the determination of 6-hydroxydopa, tyrosine, 3 O-methyldopa, and other trace amino acid impurities in levodopa preparations. The method is fast and sufficiently sensitive to determine trace impurities at 0.1% of the Jevodopa concentration with a relative standard deviation of 4-6%. The trace impurities can be estimated at ⩽0.01%.