The use of serum as a control in acid-base determination.

Samples of frozen serum of human or bovine origin have been used as an additional standard for blood acid-base analysis. The serum was used to check and compare the performance of two pH electrodes and microequilibration systems. A mean buffer line for the serum was determined at the start of the series. Daily estimations of base excess and standard bicarbonate were made. When any analysis was outside two standard deviations from the mean values, the electrode system was not considered to be functioning correctly. It could be restored to normal function by suitable cleaning. The use of a control serum will demonstrate errors in the electrode system due to protein contamination which are not evident when the system is calibrated on buffer solutions.