Accurate Determination of K, Ca and Mg in Human Serum by Isotope Dilution Inductively Coupled “Cold” Plasma Mass Spectrometry

Electrolytes in serum are important biomarkers for skeletal and cellular health. The levels of electrolytes are monitored by measuring the K, Ca, Mg and Na in blood serum. An accurate method for the determination of K, Ca and Mg in serum by taking advantage of the “cold” plasma mode and collision reaction cell of the isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) was developed. The three kinds isotope of ⁴¹K, ⁴²Ca and ²⁵Mg were added at the same time, while the contents of K, Ca and Mg were also measured. The proposed method can eliminate the need for a slow and tedious sample digestion procedure, and also can avoid the molecular ions interference. The national institute of standards and technology standard reference material 956c inorganic components in frozen human serum was analyzed by the method, and the measured elements values were in good accord with the standard values.