New Titration Method for the Determination of Uric Acid in Urine.*

Determinations of pure uric acid have been made by permanganate titrations for many years. The presence of other substances with uric acid in body fluids, which give permanganate values, has necessitated the separation of uric acid before the titration could be carried out. Such separations have never been perfect. Whether thrown down as such by treatment with stronger acids or precipitated as urates, there has always been a part of the uric acid left in solution. Hopkins’ came nearest the desired separation with his method of precipitation of ammonium urate. Probably the modification of Folin and Shaffe? has proved most useful of all, but it is distinctly imperfect since precipitation is incomplete even after 48 hours. The quantitative precipitation of uric acid by adding a soluble zinc salt and then making the solution alka,line with sodium carbonate has been described in an earlier paper.3 At that time it was mentioned that Ganassini4 had described a qualitative test for uric acid based upon a similar precipitation. It later was