Gibco Media 199 was originally formulated for nutritional studies of chick embryo fibroblasts.
Media 199 are formulated with either Earle’s salts or Hanks’ salts. Media utilizing Earle’s salts are buffered with a bicarbonate/carbonic acid system and will maintain pH in a CO2 incubator. Use of Earle’s salts in atmospheric conditions will result in rapid rise in pH of the culture medium.
Media 199 utilizing Hanks’ salts are buffered with salt solutions designed for atmospheric equilibration and use in a CO2 incubator will result in a rapid drop in pH of the culture medium.