2004 CLINICAL CHEMISTRY, Vol.33,No. 11,1987 OptimizedAtomicAbsorptionSpectrophotometryof Calcium in Erythrocytes

We sought to establish optimum conditions for measuring calcium in erythrocytes by atomic absorption spectropho-tometry. The conditions we selected are as follows. Wash one volume of fresh heparin-treated packed cells once with 30 volumes of isotonic buffered saline (pH 7.4) at a tempera-ture somewhat exceeding25 #{176}C.Dilute the washed packed cells 10-fold with 12 mmol/L hydrochloric acid, and analyze the supernate for calcium. Measure the hematocnt of the washed packed cells, then analyze an aliquot of them for calcium, using a computer-readout type of flame or a non-flame atomicabsorptionspectrophotometerequippedwith a pyrocoated graphite tube. The temperature program is 1000#{176}Cfor washing and 1800 #{176}Cfor the atomizingcycle. Intraday and day-to-day reproducibilityof the assay was 6.55 % and 8.19%, respectively,at the mean concentration o