Research Of Determination Of Selenium In Serum Using Isotope Dilution-Inductivity Coupled Plasmamass Spectrometry(ID-ICP-MS)

The predominant advantages of IDMS are high sensitive, high precise, low interference and sample treatment need not to be quantitative. It has been called the best way for trace element analysis. In recent years, this method is used to certified reference standard materials.In this thesis, the certified method for the measuring total concentration of selenium in human serum component's analysis has been studied. At the requirement of the high precise for the measurement of referenced standard materials, certified methods for the total concentration's measurement of selenium in reference standard materials of human serum with isotope dilution mass spectrometry (IDMS) has been established. The sample pretreatment methods, the optimum isotope dilution proportion, the interference problem of the peak in isotope measurement and elimination method are discussed in detail.Two methods of chemical pretreatment and separation of selenium in human serum are appilied. (1) The separation with sulphydryl cotton: sulphydryl cotton column is prewashed with 5M hydrochloric acid, Se is desorption by adding 1 mL concentrated nitric acid and the amount of Sulphydryl Cotton is 0.14 g. This preconcentration step is required for the removal of matix-interfering elements, such as Na, Mg, K and Ca. The recovery of selenium is above 92%. (2) The separation with resin AG 1×8: trace Se can be quantitatively separated from pure water. Se is eluted with 0.9M HC1. This preconcentration step is required for the removal of matix-interfering elements, such as Cl, Cu, Fe, Zn, Na, Mg, K and Ca. The recovery of selenium is above 80%.Isotope dilution mass spectrometry for measuring Se in human serum with microwave digestion-TCF separation-MC-ICP-MS is set up. The ⁷⁸Se/ ⁸⁰Se ratio of serum adding ⁷⁸Se spike is monitored by collision reaction cell MC-ICP-MS. The flow rate of Ar and H₂ respectively are 2.4 mL·min^-1 and 1.0 mL·min^-1. The measured result of Se in serum is 0.07571μg·g^-1, and Relative Uncertainty(k=2) of method is±2.1%.