Used to detect trypsin in feces. Specimen, dilute sodium carbonate solution, Grbler pure casein, 1 g sodium carbonate, H2O, and toluene are mixed together and incubated. Small samples are removed and tested with dilute acetic acid. If casein remains undigested by trypsin, white color will form. If undigested casein remains after 10Ð15 hours, there is diminution of trypsin. If color appears, carcinoma should be suspected.