SAMPLE PREPARATION STEPS FOR STANDARDIZATION OF CALCIUM-ION DETERMINATION IN AEROBICALLY-TREATED SERA ACCOUNTING FOR INFLUENCES OF TEMPERATURE AND PH

A 5 min equilibration of 0.250 mL serum sample with room air containin g 5.6% CO2, by placing the gas tube <1 cm above the sample-surface, en ables a standardized determination of calcium ion concentration (cCa(2 +)), referred to pH 7.40 and 37 degrees C, in aerobically handled spec imens. Using this method, standardized measurement of calcium ions in serum is possible with a bias less than 2%, even in samples with pH-ch anges acquired during extended storage.