HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bierman, H. R. Articles by Doan, F. J. Search for Related Content PubMed Articles by Bierman, H. R. Articles by Doan, F. J.

A Colorimetric Picric Acid Method for Determining Lactose

Maryland Agricultural Experiment Station, College Park, Maryland

ABSTRACT

In this paper we describe a picric acid colorimetric method for the determination of lactose in milk and some of its products. The results obtained by this method are compared with those obtained using the Official Gravimetric Fehling Method—Munson and Walker procedure.

REVIEW OF LITERATURE

The picric acid colorimetric method, for the estimation of carbohydrates, owes its origin to Dehn and Hartman (1) who worked with purified sugars and lactose in milk; and to Lewis and Benedict (2) who worked on glucose in blood. The method is based upon the fact that reducing sugars, in alkaline solution, (when heated) reduce picric acid which is yellow in color, to picramic acid which is a deep mahogany red. The original methods have been improved and modified for application to various sugar containing materials. Several different modifications, as applied to milk, have been published. Folin and Denis (3), report a modification using saturated picric acid and a standard which must have a color value within 20 per cent of the color value of the unknown.