Use of calmagite for the determination of traces of magnesium in biological materials

Abstract

A method has been worked out to determine traces of magnesium in some biological materials. It is based on the use of calmagite as an indicator and EGTA as a masking agent for calcium, which is generally found associated with magnesium. Though the method is liable to interference due to Cu 2+, Zn 2+, and Mn 2+ ions, such limitation may not be of practical significance as these are normally present in traces. The magnesium-dye complex absorbs maximally at 525 mμ. The sensitivity of the method is found to be 0.00123 μg/cm 2. The quantity of sample required for the analysis is of the order 100 mg for body tissues, 50 μl for serum and 10 μl each for red blood cells, urine, and milk. The validity of results has been based on recovery tests and comparison with the available literature values. Further, the results agree when test solutions are prepared in different ways, such as ashing, extraction with TCA or tungstic acid, and simply diluting with water, depending on the nature of sample. In the case of serum and milk samples, the Titan yellow method was used as a reference. The method proves to be simpler and more sensitive than the various known methods and is easily applicable to various types of biological material for routine analysis.