Determination of carbohydrates as their dansylhydrazine derivatives by capillary electrophoresis with laser‐induced fluorescence detection

A mixture of mono- and disaccharides was derivatized with dansylhydrazine in a relatively fast chemical reaction (15 min) which is selective toward aldehydes and ketones. The products of the derivatization reaction were then separated by capillary electrophoresis (CE) using laser-induced fluorescence (LIF) as the detection mode. The smallest amount of carbohydrate derivatized and determined by CE/LIF was 10 pmol contained in 100 microL of the final reaction mixture. The CE/LIF method provided a linear response for the carbohydrates tested (over 2-3 orders of magnitude), with a limit of detection of 100 amol. Separation efficiencies over 250,000 theoretical plates were obtained. The procedure was used to analyze a tear fluid sample to demonstrate the applicability of the method for the glucose determination in small volumes of biological samples.