Analysis of Mass Bias in Measurement of Selenium Isotope with Multicollectors Inductively Coupled Plasma Mass Spectrometry
The source of mass bias in collision cell-multi-collectors inductively coupled plasma mass spectrometry ( MC-ICP-MS) was investigated by varying instrumental parameters. RF power and torch positions were proved to be the main sources caused mass bias,and the flow rate of collision gases had little influence on the isotope ratio. The optimized measurement conditions to analyze isotope ratios of selenium were developed, under these conditions,the precision of measured ratio R82/76 can reach to 0. 0043% . The isotopic composition of samples GBW( E) 080215 and SRM3149 was analyzed with two selenium correction samples prepared by metrological method and based on the relationship that normalized mass bias factor was linear to the average atomic mass of the couple isotopes. Scaling to the value of R82/76 in sample SRM3149,the δ82/76 measured for GBW( E) 080215 was 4. 78‰.