Comparison of atomic absorption spectrophotometry and fluorometry for the measurement of serum calcium.

An atomic absorption spectrophotometric (AAS) and a fluorometric method for the measurement of serum calcium were found to be corn-parablein acceptable reproducibility. The recovery figures obtained by the fluorornetric procedure were considerably lower than those given by AAS in the 2-4 mEq./L. range, although recoveriesat higher levels (6 mEq./L.) were acceptable. The average recovery for the fluorometric method throughout the range 2-6 mEq./L. was 83.8%; for AAS, 98.9%. Marked interference was observedin the fluorometric method when hemolyzed or icteric serum was assayed. In four groups of hospital patients-premature infants, newborn infants, older children, and adults-AAS gave ranges for serum calcium valueswhich were higher than those obtained by fluorometry.