The Titration of Organic Acids in Urine

The simple titration method for the determination of organic acids in urine, described by Van Slyke and Palmer (I), has in many circumstances proved satisfactory. A more extended employment of the method to determine organic acids in pathological urines has brought to light limitations and sources of error which need consideration. The organic acids present in urine, both free and as salts, are estimated by titration, using suitable indicators, between the hydrogen ion concentrations represented by pH 8 and pH 2.7 respectively, after removal of the phosphates and carbonates by means of calcium hydroxide. By this procedure approximately 95 per cent of the organic acids may be determined. Weak bases, such as creatinine, creatine, and amino acids are included in the titration. A method of estimating the influence of these substances is described in the original paper.