High resolution and high throughput analytical methods for d-tagatose and process related impurities using capillary electrophoresis.

d-tagatose is a low calorie multifunctional rare ketohexose sugar with sweetness similar to that of sucrose and it has high potential benefits for food and pharmaceutical industries. It is found in traces in some fruits as a natural component. In view of its high demand as a substitute for sugar, mass production of d-tagatose through enzymatic conversion of Lactose to d-tagatose is adopted. The existing HPLC method has limitations with respect sensitivity and resolution in quantification and monitoring of d-tagatose in the presence of its process related impurities. In the present investigation a new robust, fast and green analytical technique has been developed based on capillary electrophoresis (CE) for the separation and quantification of d-tagatose in presence of other sugars: Lactose, d-glucose, d-galactose and d-talose. Optimum conditions are found to be: Back Ground Electrolyte (BGE): 36 mM of NaHPO and 130 mM of NaOH; pH: 12.6; voltage: +18 kV for high resolution and -18 kV for high throughput methods with direct UV-Detector at 265 nm. At these optimum conditions, good separation between the sugars is achieved in less than 20 min for high resolution and less than 4 min for high throughput methods. The developed methodology is validated as per ICHQ2R1 guide lines and successfully applied for monitoring d-tagatose during the enzymatic conversion of Lactose/d-galactose to d-tagatose and also to determine the unknown amounts of d-tagatose in crystallized samples and further, it is used in identifying the d-tagatose in fruits.