Hanks' salts
From Infogalactic: the planetary knowledge core
Hanks' Salts is a collective group of salts rich in bicarbonate ions, formulated in 1940 by the microbiologist John H. Hanks.[1] Typically, they are used as a buffer system in cell culture media and aid in maintaining the optimum physiological pH (roughly 7.0-7.4) for cellular growth. Due to their poorly reactive nature and small concentration in solution, Hanks' Salts are mainly used in media that are exposed to atmospheric conditions as opposed to CO2 incubation. Performing the latter drastically exceeds the buffer capacity of Hanks' Salts and may result in cell death.