This test was developed to offer a rapid method of detecting chloroquine in urine samples under field conditions, where it may be used as a means of determining whether a population is ingesting the drug. The test is based on the method described by Brodie and Udenfriend (1945) for the estimation of basic organic compounds in biological material by salt formation with methyl orange.
Reagents. Sodium hydroxide solution, 10 per cent.
Ethylene dichloride, purified grade. Chloroform may be substituted for this reagent if necessary.
Methyl orange solution. Prepare a boric acid solution by dissolving 5 gm. of boric acid in 100 ml. of water. To this solution add 0.1 gm. of indicator-grade methyl orange and shake the mixture for a few minutes. The solid dissolves rapidly, followed in a few minutes by the formation of a precipitate. Allow the solution to stand for a few hours or overnight and then filter it.