Sulfur-specific detection of impurities in cimetidine drug substance usingliquid chromatography coupled to high resolution inductively coupled plasma mass spectrometry and electrospray mass spectrometry

The use of liquid chromatography coupled to sector field inductively couple d plasma mass spectrometry (SF-ICP-MS) for the specific detection of sulfur -containing compounds is described. In the sulfur-containing drug substance cimetidine, structurally related impurities well below the 0.1 % mass frac tion. level relative to the main drug substance could easily be detected. T he structure of most of the impurities was confirmed by electrospray mass s pectrometry (ESI-MS), and thus, the complementarity of the two techniques f or drug analysis is shown. The limit of detection by SF-ICP-MS for cimetidi ne in solution was similar to4-20 ng.g(-1), but it was blank-limited.