Optimization of a Colorimetric Test Method for Quantifying Glycerol in Aqueous Solution

Abstract

Many analytical methods for glycerol involve chemical techniques or instrumentation that may be unavailable to small biodiesel processors or have potential interactions with other components in the glycerol phase. This work presents an analytical method based on periodate oxidation of glycerol to formaldehyde, which is then quantified using a modification of the Nash test required to remove excess periodate. The method provides a linear calibration over the range of diluted glycerol concentrations from 0.02 to 0.25 mM and is limited at high concentrations by the formation of precipitate during the Nash test. There are no observed interferences from the formic acid coproduct of the glycerol oxidation or from potential contaminants in the crude glycerol, which includes methanol and sodium. Several disaccharides and starch, both as individual solutes or in glycerol solutions, gave no response under the conditions of the described method.