(Solved): Chromatography is used in many applications including the analysis of structurally related impuritie ...

Chromatography is used in many applications including the analysis of structurally related impurities in pharmaceuticals and the levels of pharmaceuticals in patients. Suggest why chromatography is required in the situations above, rather than, for example, UV Spectrophotometry, to determine the levels of a pharmaceutical in the same samples. (4 marks) A sample made from dissolving and filtering one tablet, containing caffeine, paracetamol and aspirin was analysed by reversed phase HPLC. Conditions: Column (X), Mobile Phase:

Formic acid: Acetonitrile [10:90] a) Suggest a column chemistry to replace ( X ), and state which would be the strong solvent within the mobile phase. (2 marks) b) On initial analysis, the peaks of paracetamol and caffeine were not resolved and had significant coelution. Suggest changes to the experiment that may provide full resolution of all of the compounds, and relate the change to a chromatographic variable (e.g. efficiency). ( 2 marks)