VOLUME19, NO. 12 Upjohn Company, using an adaptation of the hollow-cup agarplate method (10).

Ethylene and 1 ,I-propylene glycols can be determined simultaneously b y periodate oxidation to formaldehyde and acetaldehyde which are determined polarographically after a simple distillation.The method is applicable to the analysis OF mixtures of formaldehyde and acetaldehyde as well as to the determination of other substances which form these aldehydes on treatment. The principal limitation of the method is that there must not be formed any other volatile substances polarographically reducible under the same conditions as the aldehydes.LTHOUGH several methods for the quantitative deter-A mination of glycols have been described in the literature, little attention has been given to their determination in mixtures of each other. Those methods that have been used involve tedious and time-consuming procedures. I t seemed desirable, therefore, to obtain a simple and rapid method for quantitatively determining the amounts of ethylene and 1,2-propylene glycols in the presence of one another.The method described in this paper consists essentially of oxidizing the glycol mixture with periodic acid to give formaldehyde and acetaldehyde according to the following equations:CHSOH CHzOH + HI04 + 2HCHO + HI03 + HsO CHI. CHOH. CHzOH + HI01 + HCHO + CHI CHO + HI03 + HzOThe resulting aldehydes are then determined polarographically. From an examination of the equations of the reaction, it is seen that the acetaldehyde content gives a measure of the propylene glycol concentration. The ethylene glycol can be estimated by deducting the formaldehyde produced by the oxidation of propylene glycol from the total amount of formaldehyde found in the mixture.Johnson (5) determined 2,3-butylene glycol by oxidizing it with potassium periodate in an acid medium to give acetaldehyde. This was distilled into a standard bisulfite solution to form the bisulfite addition product, which was subsequently determined by titration of the bound bisulfite with standard iodine solution. Hoepe and Treadwell (5) described a method utilizing the hIalaprade reaction for the determination of glycerol, ethylene glycol, and 1,2-propylene glycol in mixtures. The resulting formic acid, total aldehyde, and formaldehyde were determined titrimetrically on aliquots of the oxidized solution. Mixtures of formaldehyde and acetaldehyde were determined by Ionescu and Slusanschi (4) using dimedon (dimethyldihydroresorcinol) as a precipitant, and noting the length of time required for the crystals to appear.Boyd and Bambach (1) described a polarographic method for the detcrmination of formaldehyde as a step in the procedure for the determination of serine in protein hydrolyzates. The method consisted of treating the hydrolyzate with periodic acid, quantitatively separating the resulting formaldehyde by distillation, and determining it polarographically using 0.05 N potassium hydroxide in 0.1 N potassium chloride as the supporting electrolyte solution. The effect of the presence of other aldehydes such as acrolein, acetaldehyde, and propionaldehyde on the determination of fo...

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