HPTLC-MS analysis of melamine in milk: standardization and validation

Melamine containing large amount of nitrogen may be deliberately added to milk in order to increase the protein content for economic adulteration in food stuffs. High performance thin layer chromatography-mass spectrometry (HPTLC-MS)-based method of quantification of melamine has been developed using Silica gel 60 F-254s HPTLC plates, with optimized mobile phase iso-propanol/dichloromethane/water, 5:2.5:3, v/v/v in a twin trough chamber saturated (5 min) at pH 6.8. Validation was carried out by testing its specificity, linearity (1-50 mu g), accuracy (95.908-98.369%), inter- and intraday precision (1.578 and 1.670%), respectively, limits of detection (2.688 ng) and quantification (8.146 ng). HPTLC in combination with MS has been found suitable for routine analysis of melamine added as adulterant to market-purchased milk samples.