A method for the determination of iodine is described, based on the reaction of acetone, iodine and potassium hydroxide as monitored with an iodide-selective electrode. This method is more sensitive than those previously de~cribed.l-~ Kinetic methods of analysis and ion-selective electrodes have recently been recognised as useful means for the determination of individual elements, catalysts, enzymes, substrates, inhibitors and activator^.^-^ In a previous paper Altinata and Pekin described the determination of molybdenum and tungsten by using an iodide-activity electrode.10Nikitin and Kochkin4 have determined iodine by using a kinetic method, based on the determination of the rate of development of turbidity in solution with time. Three readings were taken of the turbidity time (tz) and they carried out similar measurements on two control solutions (tl and t2). They calculated the concentration of the iodine used as a substrate for the reaction between acetone, iodine and potassium hydroxide by applying the equation given in the literature.There are three steps in the reaction between acetone, iodine and potassium hydroxide. These partial reactions can be summarised as the following net reaction:

A new method f o r the determination of molybdenum and tungsten i s described based on their catalysis of the hydrogen peroxide-iodide reaction a s monitored with a n iodide ion-selective electrode. method yields better results than methods previously used. example, Yatsimirskii and Afanaseva and Erdey and Svehla have found a lower limit of 0. 0 2 and 0. 1 p g / m l f o r molybdenum I n the present work a s little as 0. 004 pg/ml of molybdenum and tungsten is determinable. This For i 2

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It has been found that boric acid and chloride ions suppress the reducing power of glucose and maltose. While boric acid does not affect the linearity of absorbance versus concentration curves, nonlinearities may occur if chloride is present in the solution to be analyzed. It has also been found that the proper upper limit of the alkaline copper method is 175 μg/ml for glucose, as opposed to the commonly adopted value of 300 μg/ml.

Acidic hydrolysis of starch, in contrast to enzymatic hydrolysis, gives a very low degree of multiple attack. By making use of this property it seems possible to prepare polysaccharide mixtures with very narrow ranges of molecular weight distribution. In a commercial sample of soluble starch the ratio of weight to number average molecular weights (M̄w/M̄n), which is a direct measure of polydispersity, is decreased from 3.1 to 1.2 by acid hydrolysis followed by ethanol‐water precipitation.