[Investigation of the impurity profile of nifedipine by LC/MS].

The manufacture-characteristic impurity profile of nifedipine drug substance was studied by HPLC and on-line LC/MS coupling. Using a new gradient HPLC procedure and MS detection, spectroscopic evidences for the chemical structure of some previously unknown minor impurities (all under 0.1%) were obtained.

[Investigation of tofizopam impurities using high performance liquid chromatography].

The identification and quantification of potential impurities of Tofisopam have been studied by high performance liquid chromatography. The best separation was obtained in a reversed phase system using a C18 stationary phase and 46:31:23 mixture of 0.01 M aqueous 1-hepatanesulphonic acid-sodium-acetonitrile-methanol as the mobile phase.