SOME FACTORS AFFECTING THE DETERMINATION OF FURFURAL

Abstract

The previous observation by Stillings and Browning that methylfurfural and hydroxymethylfurfural do not interfere with the photocolorimetric determination of furfural with aniline has been confirmed. The color of the furfural – aniline acetate compound was stabilized satisfactorily by oxalic acid and sodium chloride; the addition of disodium phosphate brought about minimum transmittance. Recoveries of furfural distilled from 12% hydrochloric acid were 99.0 and 99.7% as measured by the photocolorimetric and excess bromine titration methods respectively. Xylose was converted to furfural in 90.6% yield by simple distillation with 12% hydrochloric acid saturated with sodium chloride. Rapid steam distillation increased the recovery to 91.6%. Dextrose, levulose, cellulose and rhamnose gave apparent furfural yields by the excess bromine titration method but negative results with the photocolorimetric method. The two methods were applied to 13 plant residues whose furfural contents ranged from more than 30% in 'Beewing' wheat bran to less than 5% for peat. The results obtained by the photocolorimetric method, regarded as being the true furfural contents, are 2 to 3% lower than those obtained by the titration method.