Colorimetric and fluorometric carbohydrate determination with p-hydroxybenzoic acid hydrazide

The reaction of p-hydroxybenzoic acid hydrazide and reducing carbohydrates in alkaline solution can be used in colorimetric and fluorometric assay procedures. These are capable of determining glucose at concentrations from less then 0.1 μg/ml up to levels found in human serum. A colorimetric procedure is based on the formation of an intensely yellow calcium chelate of the derivative, and a fluorometric procedure on the fluorescence of a lanthanum chelate in diethanolamine solution. The methods are specific for reducing carbohydrates and are subject to few noncarbohydrate interferences.