A Spectrochemical Determination of Sodium in Blood Serum*

A spectrochemical method for the quantitative analysis of sodium in blood serum has been worked out and used during the past 2 years for routine analyses. It differs in several respects from the methods described by Thomson and Lee (l), Langstroth (2), and Duffendack et al. (3) for measuring sodium in body fluids. The first two require specially constructed sparking arrangements for exciting the sample; the third employs a high voltage A.C. carbon arc. In the present method the regular low voltage D.C. carbon arc equipment is used, with only slight modification (this is manufactured as standard equipment by the Bausch and Lomb Optical Company) and a Bausch and Lomb medium quartz spectrograph. For the sake of completeness and for future reference, the method will be described in detail, although some of the procedures concerning excitation in the low voltage D.C. arc between graphite electrodes are in common use and recently have been discussed by other workers, particularly Cholak (4), Cholak and Story (5), Owens (6), and Pierce et al. (7).