A Simplified Method for Determining Bile Salts in Bile

Abstract

The metabolism of bile salts has received little attention due to the lack of a quantitative method which would give accurate results on small amounts of material. Five types of method have been tried: (1) using the Pettenkofer color reaction between cholic acid, furfural and concentrated sulfuric acid; (2) using separation of the bile acids and determination by weight; (3) stalagmometric methods depending on the property of bile salts to lower surface tension; (4) involving hydrolysis of the salts and subsequent determination of the amino nitrogen of the free taurine and glycocholic acid; (5) utilizing the fact that ferric salts of bile acids are insoluble.

Detailed criticisms of these methods by Hooper and Foster 1 and Schmidt and Dart 2 show that they are either too inaccurate or too laborious to be practical. One of the simplest recent methods is that of Szilard 3 who made use of a principle that has long been known, that bile salts are precipitated by ferric chloride, 4 and found that the iron in the precipitate is proportional to the bile salts present. In attempting to use this method and the modifications introduced later by Katayama, 5 it was found that the method was inaccurate and uncertain for small quantities of bile salts. Attempts to improve the technic have resulted in a new method which resembles that of Szilard only in its basic principle.

The new procedure is as follows: 5 cc. of bile are pipetted into a 100 cc. flask and diluted with 90 cc. of distilled water. Two cc. of 2 M (44%) calcium chloride, and 2 cc. of 4 M KOH are added and the whole is thoroughly mixed by shaking.