Fluorescence of Boron Complexes. VI. Fluorometric Determination of Salicylic Acids

The fluorescence reaction of salicylic acid and its derivatives with boric acid was successfully applied to their micro-analyses. The recommened procedures were as follows : Seven milliliters of the glacial acetic acid solution of a sample of salicylid acids (5×10-6-5×10-8M) was mixed with 1.0 ml of sulfuric acid-glacial acetic acid solution with concentration represented in Table II, 1.0 ml of acetic anhydride, and 1.0 ml of boric acid-glacial acetic acid solution, stoppered and allowed to keep at 60° for 10 min. Then the fluorescence intensity of the solution was measured at the excitation and fluorescence maxima of each of the samples shown in Table II. In the case of 4-hydroxysalicylic acid and 5-aminosalicylic acid, 8.0 ml of each solution was mixed with 1.0 ml of 5% boric acid-acetic anhydried solution, and the mixture was kept at 60° for 10 min. Then 1.0 ml of 0.01 N sulfuric acid solution in-glacial acetic acid was added to the mixture. The coefficients of variation for these four compounds (1×10-6M) were 0.8-1.0%. Among diverse compounds, quinie ethylcarbonate disturbed the determination. This fluorometry was applied to the determination of salicylid acid in fermented liquor, blood plasma and urine, and the analytical results agreed well with those obtained by the colorimetric method.