Normal Values and Comparison of Atomic Absorption Spectrophotometric and }-; luorometric Methods for Determination of Serum Magnesium

Abstract

The diagnostic implications of change in serum magnesium levels have been evident in recent years. 1> 2) Serum magnesium level, however, like serum calcium, normally are maintained within very narrow limits so that higly accurate and specific analytical methods are required to detect the relatively small changes which may occur in certain disease states. The magnesium content of biological fluid has been investigated by many workers using a variety of procedures, including magnesium phosphate precipitation, 3) cornplexometric titration, 4, 5) photometry, 6, 7) and emission flame photometry. 8, 9, 10) Schachter!'? noted the fluorescence of the magnesium compound of S-hydroxyquinoline in ethanol and used this property for quantitative fluorometric assay. The fluorometric procedure possesses distinct advantages in that it is specific, accurate, rapid, and employs a very small sample. Atomic absorption spectroscopy was developed by Walsh!" as an analytical technic applicable to the determination of many metals. The use of atomic absorption spectroscopy for the determination of magnesium in serum was reported by Willis I 3, 14) in 1959 and 1960, using direct measurements on serum diluted with an aqueous EDTA solution. Subsequent modifica tions have involved other direct dilution methods 15-21) or protein precipitation. These published results indicated that atomic absorption spectroscopy would be a simple, rapid, and practical method for the determination of magnesium in biological material, particulary in serum and urine, and that it could be adapted effectvely to the needs of a clinical chemistry laboratories. As we required an accurate and reproducible method for estimating serum magnesium, it was decided to compare both procedures, fluorometry and atomic absorption spectroscopy. In addition, it is the purpose of this report to complete the normal ranges of magne-sium in serum of healthy Korean persons as reference points evaluating pathologi c condi tions.