RPI media is now available in convenient premeasured and pre-mixed capsules. Prebuffered media eliminates pH adjustments, dust and smells from the lab.Low Salt Formula. Molecular Biology Grade. For propagation and maintenance of E.Coli: Add 1 capsule per liter of water. Heat and stir until capsule is completely dissolved. Buffer is set for 7.2 at 20?C using a 10mM solution of TRIS/TRIS HCl Sterilize by autoclaving for 15 minutes. Ingredients: Tryptone: 10 g/L Yeast Extract: 5 g/L Sodium Chloride: 5 g/L