IFCC reference methods for measurement of pH, gases and electrolytes in blood: reference materials.

The Scientific Division Committee on pH, Blood Gases and Electrolytes of the International Federation of Clinical Chemistry (IFCC) produced recommendations to attempt to make the results of pH, blood gas and electrolyte analysis from different clinical chemistry laboratories internationally compatible. The aim of this lecture is to discuss the essential aspects of 1. the IFCC approved (1986) reference method for pH measurement in blood, 2. the IFCC approved (1988) reference method for tonometry of blood, 3. the provisionally proposed recommendations on the expression of results obtained with ion-selective electrodes for measuring sodium, potassium and calcium in serum, plasma or blood and 4. the reference method for the determination of ionized calcium in serum, plasma or blood. Also reference materials for quality control of pH, blood gas and electrolyte measurements are reviewed. Failures of several types of currently available quality control materials are discussed.