WATER ANALYSIS 2015 285 49.Tryptophan Medium Ingredients g/l Casein enzymic hydrolysate : 10.0 Sodium chloride : 5.0 DL-Tryptophan : 1.0 Final pH (at 25°C) 7.5±0.1 Directions: Suspend above ingredients in 1000 ml distilled water. Heat if necessary to dissolve the medium completely. Adjust the pH and dispense into tubes. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. 50.Urea Agar Base, Christensen Ingredients g/l Peptic digest of animal tissue : 1.0 Dextrose : 1.0 Sodium chloride : 5.0 Monopotassium phosphate : 2.0 Phenol red : 0.012 Agar : 15.0 Final pH ( at 25°C) 6.8±0.1 Directions:Suspend above ingredients in 950 ml distilled water. Heat if necessary to dissolve the medium completely. Adjust the pH and sterilize by autoclaving at 10 lbs pressure (115°C) for 15 minutes. Cool to 50°C and aseptically add 50 ml of sterile 40% Urea Solution and mix well. Dispense into sterile tubes and allow to set in a slanting position. Do not overheat or reheat the medium as urea decomposes very easily.