Urinalysis - The Carter Center

immediately. For this reason, Gerhardt's Test is performed whenever a
positive reaction occurred with Rothera's or Lang's Test.
Principle of the Test
When acetoacetate (diacetic acid) reacts with a ferric chloride (FeC1 3 )
solution, Bordeaux red color is formed.
Procedure
1. To 5ml fresh urine in a test tube, add 10 % ferric chloride solution
drop by drop until any precipitate of ferric phosphate dissolves. This
generally takes 5 - 10 drops of ferric chloride.
Filter if necessary, and add more ferric chloride.
If a red- brown to Bordeaux red (dark red) color appears, it merely
indicates the possible presence of acetoacetate since other substances
(phenol, salicylates, salicylic acid and sodium bicarbonate) can give a
similar color.
To confirm the presence of acetoacetic acid, divide the test solution in
half and boil one portion for 5 minutes. If the color disappears or
becomes lighter after boiling, acetoacetic acid is present. If the color
remains unchanged after boiling, one of the interfering substances is
present.
Report the result as positive or negative for acetoacetic acid.
Preparation of 10 % Ferric Chloride Reagent (See Reagent Number 8)
4.3 Determination of Urinary Protein
Introduction
Protein is a macromolecule, composed of one or more polypeptide
chains, each possessing a characteristic amino acid sequence and
molecular weight. It has many biologically important functions. Some
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