DETERMINATION OF GLUCOSE AND STARCH BY THE 
ALKALINE POTASSIUM PERMANGANATE METHOD! 
By FrRANcIsScO A. QUISUMBING 
Of the Laboratory of Agricultural Chemistry, College of Agriculture, 
University of the Philippines 
SIX TEXT FIGURES 
No one analytical method has been so useful in the analysis 
of saccharine products as has Fehling’s in its numerous modifi- 
cations, though many attempts had been made to substitute 
others, entirely different in principle, for the copper-reducing 
method. Results have shown that the substitutes have not 
been as satisfactory, and the copper-reducing method has there- 
fore remained in its classical use. In its more recent modifica- 
tions, it is one of the most accurate and convenient methods we 
have. At first sight, it might appear a superfluous task to at- 
tempt to find a substitute for such a reliable method, but I 
thought it would be worth while to work out an entirely dif- 
ferent, simpler, and more rapid one to save time and material 
in the numerous analyses of starchy products that the depart- 
ment of chemistry has to perform in connection with the inves- 
tigation of the feeding values of grains and root crops. 
Among the many other possible methods, the alkaline potas- 
sium permanganate appeared to me to be the most promising. 
Previous preliminary experiments have shown that, when glu- 
cose was oxidized by alkaline potassium permanganate solution 
of a definite concentration, the amount oxidized decreased with 
increase in concentration of the former, if the length of time 
of heating was the same. The same thing has been observed 
also by Witzemann and others. I have studied the conditions 
of the reaction, by using different concentrations of alkali and 
of potassium permanganate, and by standardizing the time of 
heating, as was done with the copper-reducing method. From 
the results obtained a procedure was worked out for the deter- 
“This investigation was undertaken at the suggestion of Assistant Pro- 
fessor Manuel L. Roxas and carried out under his personal supervision. 
The author desires to express his thanks and appreciation to Professor 
Roxas for his advice and suggestion. 
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