Comparison of serum magnesium values by photometric, fluorometric, atomic absorption, and flame emission methods.

liVEETHODS of magnesium deternmination immbiologic fluids constitute an extensive literature. Magnesium ammonium phosphate precipitation (1), complexometric titration (2, 3), photometry (4, 5), fluorometry (6, 7), atomic absorption (8-11), and flame emission photometry (1214) have been employed for serum analysis. “Normal” ranges reported by these methods have been repeatedly tabulated (15-16) but show considerable divergence. In previous studies of clinical variation of serum magnesium levels, we had used the method of Simonsen et at. (i), but current needs demanded a simpler, faster, and less expensive method which was at the same time precise and accurate. Lacking instrumentation for atomic absorption or flame emission and having no interest in complexometric titration, we turned our attention to two particular photometric mnethods and two versions of a fluot-ometric method. ill the study we planmied to establish control “nom-mal’’ rammges as referemmce points for evalilating pathologic change. Comparison with atomic absorption and flammie emission values were afforded through the courtesy of other investigators. The purpose of this paper is to report the comparative results on aliquots of the same serum specimen, analyzed by time methods de-