Determination of reducing sugars in the nanomole range with tetrazolium blue.

Addition of sodium potassium tartrate to basic solutions of tetrazolium blue [(2,2',5,5'-tetraphenyl-3,3'-dimethoxy 4,4'-biphenylene) ditetrazolium chloride] greatly improved their efficacy as colorimetric reagents for reducing sugar determination. This modification increased sensitivity and decreased reaction time. The modified reagent can determine as little as 1 nmol of neutral sugars as well as 2-amino and N-acetyl amino sugars.