Determination of zolpidem hemitartrate by quantitative HPTLC and LC

Two methods are described for the determination of zolpidem hemitartrate in presence of its degradation product. The first method was a TLC-UV densitometric one in which the mobile phase methanol: water (20:80) was used for developing the TLC plates. The R-f of zolpidem hemitartrate was found to be 0.29+/-0.01 and that of its degradation product was 0.59+/-0.01. Linearity range was 0.5-4 mug/spot with mean recovery percentage (99.98+/-0.988)%. The second method was an HPLC method. HPLC was performed on a Bondapack C-18 column. The mobile phase was composed of a mixture of acetonitrile-0.01 M KH2PO4 (40:60). The pH was adjusted to 3.5+/-0.1. Flow rate was 1.2 ml/min. Calibration graphs were linear in the range of 0.5-5 mug/ml with UV detection at 245 nm. Both methods have been successfully applied to pharmaceutical formulations. The results obtained were statistically compared with those obtained by applying the reported methods. (C) 2003 Elsevier B.V. All rights reserved.