A sensitive fluorometric assay for reducing sugars.

A simple and rapid fluorometric assay for reducing sugars that is sensitive to the nanomolar range has been developed. The assay involves the derivatization of a given sugar with hydrazine at pH 3 to form a hydrazone, which is reacted with fluorescamine following adjustment of pH to first 9.4 and then 7.4. The amount of sugar in a sample is quantitated by measuring the fluorescence intensity at an excitation wavelength of 400 nm and an emission wavelength of 490 nm. The assay is precise and reproducible, as indicated by intra- and inter-run variations of at most 3% and 4%, respectively. In addition to reducing sugars, the assay can also be used to measure aliphatic and aromatic aldehydes, but not acetone. Compared with an existing fluorometric sugar assay, the assay reported here does not require chromatographic separation of the fluorescent derivative from unreacted fluorescamine. The assay can, however, be potentially adapted for postcolumn detection of aldehydes, reducing sugars, and hydrazones in HPLC.