Interference—free Flame Photometry of Calcium in Serum and Urine

Abstract

Data are given for the rapid determination of calcium in biologic material by flame photometry. An "automatic background-subtraction," photometer added to the available instrumentation eliminated cation interference, while the use of a chelating agent (EDTA) prevented interference from anions (chiefly phosphate). The procedure shows excellent precision and accuracy in comparison with standard chemical procedures and in the analysis of control sera.