Vitamin Analysis by Capillary Electrophoresis

Introduction :

Capillary electrophoresis (CE) is a relatively new technique, which has expanded considerably in the last decade. Such rapid development is the result of several factors: sample preparation is reduced to a minimum, separation can usually be achieved quickly and solvent requirements are minimal. With the method we have developed to analyse citrus juices, preparation requires only filtration and dilution. The separation is rapid, up to thirty citrus juice compounds can be separated in 20 min. There is no reconditioning period between each analysis and after a 3 min wash a new sample can be started. These CE characteristics are well suited for continuous analysis with little intervention from the analyst. Finally, the use of the instrument is very cost effective. Seventy centimetres of bare fused-silica capillary cost very little and the same tubing can be used for several years, if maintained properly. Considering that the capillary diameter is 50 µm, samples can be run with very small amounts of buffer; this is also an important point considering the cost of buying and disposing of solvents. Finally, the problem of detection limit, which was a major drawback in early CE, has now been largely resolved and CE detection is now similar to that of high performance liquid chromatography (HPLC). Numerous CE procedures have been developed to analyse a large variety of organic and inorganic compounds.1–4 CE has been applied successfully in the areas of pharmaceutical analysis,5,6 clinical chemistry7 and food analysis.8–11 A significant number of these published papers were dedicated to vitamin analysis in pharmaceutical research13 and in food analysis.14,15

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