Phenolsulphonephthalein, which was first described by Remsen,1 is a bright red crystalline powder, somewhat soluble in water and alcohol and readily soluble in the presence of alkalies. The drug, as determined by Abel and Rowntree,2 is non-toxic, non-irritant locally, and is excreted practically entirely by the kidneys and with extraordinary rapidity, appearing in the urine normally within a few minutes of injection. In alkaline solution it presents a brilliant red color which is ideally adapted for quantitative colorimetric estimation.
In our earliest work only the time of appearance, the time of maximum intensity of excretion, and the time of gross elimination were considered. In the course of the work it became evident that the color properties of this substance make it peculiarly well adapted for colorimetric methods of estimation, and for this purpose the Duboscq colorimeter was employed and has proved of the
ROWNTREE LG, GERAGHTY JT. THE PHTHALEIN TESTAN EXPERIMENTAL AND CLINICAL STUDY OF PHENOLSULPHONEPHTHALEIN IN RELATION TO RENAL FUNCTION IN HEALTH AND DISEASE. Arch Intern Med (Chic). 1912;IX(3):284–338. doi:10.1001/archinte.1912.00060150013002