A Method for Determination of Magnesium in Serum and Urine.

TiTHE PHYSIOLOGIC and pathologic consequences of magnesium deficit or excess iii animals, and the important role of magnesium as a cofactor in many enzyme systems have been well recognized. However, knowledge concerning the role of magnesium in human disease has lagged behind that of sodium and potassium. This has been, in part, due to the fact that methods for the determination of magnesium in biologic material have been time-consuming and less accurate than the rapid flame-photometry method available for the determination of sodium and potassium. The concentrations of magnesium in biologic fluids in various pathologic states have been reviewed by Martin et a. (1), Hasselman and Van Kampen (2), and Maclntyre (3). This paper presents a simple and accurate spectrophotometric method for tile determination of magnesium in serum and urine. The principle used was first described by Kolthoff (4), who showed that the dye, thiazole yellow (methylbenzothiazole[1,3] -4,4’-diazoaminobenzol-2,2’-disulfonic acid), combined with magnesium hydroxide in alkaline solution to form a red lake, the intensity of which was proportional to tile magnesium concentration. This adsorption of thiazole yellow on colloidal Mg(OH) particles was confirmed by Glemser and Dautzenherg (5), who examined the sediment with the aid of X-ray diffraction.