Some Modifications of the Picric Acid Method for Sugars

The writers recently had occasion to use the picric acid colorimetric method (commonly called the Benedict-Lewis method) 2 for determining the sugars in cornstalk juices. Although it has been used mostly as a micro method for blood and urine analyses, it has been used to some extent as a macro method. {3* 5, 12.) It proved to be more rapid than, and approximately as accurate as a, copper reduction method after certain modifications had been introduced to eliminate certain sources of error. The following is a description of the errors met with and the corresponding modifications.