ROTI^®Cell EDTA solution, 100 ml

In addition to the various nutrients in the medium, the pH value also plays a very important role in cell culture. The physiological pH for almost all mammalian cells is 7.4. Deviating from this, it has been observed that certain transformed cell lines prefer a pH between 7.0 and 7.4 and certain fibroblasts prefer a pH between 7.4 and 7.7. In any case, pH fluctuations should be avoided and the pH should be maintained as well as possible. That is why a buffer system in media is necessary. The most important buffer system in the body is the carbonic acid-carbonate buffer system. Accordingly, almost all cell culture media contain bicarbonate (NaHCO₃). Bicarbonate alone leads to a strong pH increase of the medium, so that NaHCO₃-buffered media must always be used with CO₂ incubators. Depending on the NaHCO₃ concentration in the medium, different CO₂ environments are necessary to ensure a pH of about 7.4. For this reason, you should not work outside of the CO₂ incubator for too long. If this is necessary, a HEPES buffer should be used in addition to the NaHCO₃, which contributes as a second buffer system to stabilize the pH value.