Analysis of lactose hydrolysis in milk by pre-column derivatization HPLC

A simple and sensitive pre-column derivatization method is described for the analysis of lactase hydrolysis in milk using high performance liquid chromatographic(HPLC).The 1-phenyl-3-methyl-5-pyrazolone(PMP) derivatives of Lactose,glucose and galactose were separated by reverse-phase HPLC using a gradient elution process,and monitored by ultraviolet detector at 245 nm.The result showed that the method could detect accurately the process of lactase hydrolysis.The optimal hydrolysis time is at 3-4 hours.On the other hand,the method could analyze reducing disaccharide directly,which may be useful for the analysis of sugars in dairy product.