The determination of metals in blood serum by atomic absorption spectroscopy-II Magnesium

The magnesium content of blood serum may be accurately determined by atomic absorption measurements. Analysis can be carried out on as little as 0.05 ml of serum and the only preliminary treatment necessary is dilution of the sample with water containing about 1 per cent of ethylenediaminetetracetic acid or of strontium chloride. Existing methods for estimation of magnesium THE lack of detailed knowledge of the functions of magnesium in the body is largely due to the absence of rapid and accurate methods for its routine estimation in biological materials [1,2]. The existing methods are all more or less tedious and require relatively large amounts of sample, so that routine determination of magnesium is not at present practised in many hospital laboratories. Chemical methods Apart from the classical procedure in which the magnesium is precipitated as magnesium ammonium phosphate most of the methods which have been proposed for the determination of this metal in serum rely on a complexometrio titration with ethylenediaminetetracetic acid and require prior removal of both protein and calcium [3-61. The quantity of serum required is usually l-2 ml, though in a recent version of the complexometric method which uses a photoelectric titrator WILKINSON [7] has determined magnesium on as little as 0.1-0.2 ml without prior removal of protein or calcium. HUNTER [8] has described a calorimetric method for measuring the magnesium content of serum after deproteinization, which requires only 0.2 ml of serum but like WILKINSON’S method has the disadvantage of determining magnesium indirectly as the difference of two titrations, one giving the calcium content and the other the combined calcium and magnesium content. Errors may also arise from the traces of copper and zinc present in serum. [l] J. R. ELKINTON, C&n. Chem. 3, 319, 331 (1957). [2] W. E. C. WACKER and B. L. VALLEE, New EngZ. J. Med. 259, 431 (1958). [3] K. J. KARRMAN and S. BORUSTR~M, Svenek. Kern. Tidskr. 61, 18 (1955). [4J H. S. FRIEDMAN and M. A. RUBIN, CZin.Chem. 1, 125 (1955). [5] A. A. Wmoii, J. Camp. Path& Therap. 85, 285 (1955). [6] H. FLASCHKA, A. A. ABD. EL RAHEEM and F. SADEK, 2. Physiol. Chem., Hoppe-Seyler’s, 310, 97 (1958). [7] R. H. WILKINSON, J. CZin. Pathol. 10, 126 (1957). [S] G. HUNTER, Analyst 84, 24 (1959).