Abstract
The determination of calcium in biologic fluids by atomic absorption spectrophotometry is interfered with by the presence of protein, cations, and those anions that form complexes with calcium. Such interference was overcome when lanthanum was included in a 1:50 dilution of serum or urine. Recovery of calcium added to calcium-free serum was 100%. The S.D. based on double-blind duplicates was 0.22 mg./lOO ml. Excellent statistical agreement was found between the test method and each of the 2 reference methods.
