| Selenium(Se)is an essential trace element widespread in environment.With multiple oxidation states and six stable isotopes,Se isotope system not only has great potential in tracing the redox conditions of continental surface,serving as a paleo-oceanographic proxy,but also can be used in many other fields such as environmental science,agriculture science and life science.However,at present,the Se isotope analysis method is still a little insufficient,when using thiol cotton fiber for purification,the experimental time is too long,and the organic matter introduced in the solution is not easy to remove,which brings difficulties to obtain accurate data of selenium isotope ratios.Therefore,it is urgent to develop a quick and simple method with less interference that can be applied to all kinds of samples.Based on previous research work,the chemical purification process of Se isotopes in geological and environmental samples was optimized by using silica-based thiol resin.With hydride generator(HG)and multiple collector inductively coupled plasma mass spectrometry(MC-ICP-MS),an improved method for precise Se isotopes analysis was established.(1)The improved chemical purification process takes less time,is easier to operate,and achieved good results.The recoveries of the samples ranged from 80%to 100%,and the Ge/Se ratio in the purified solution was less than 2.83Χ10-4,As/Se?8.70Χ10-2,which indicates the removal of interference elements is successful,reaching the requirements of high-precision measuring.(2)The double spike method(DS method)was used to correct the mass bias effect in chemical purification and mass spectrometry.The long-term test result shows the?82/76Se values of the isotope standard solution NIST SRM 3149,MH495 and GBW were 0.00±0.15(2SD,n=191),-3.42±0.15(2SD,n=20)and-7.92±0.12(2SD,n=9)respectively,showing the results are in basic agreement with previous data.(3)The intermediate precision of Se isotope determination of the selected geological,environmental,and biological reference materials was between 0.10(2SD)and 0.20(2SD).The?82/76Se values ranged from-1.42to 2.63.In addition to SGR-1b and NIST 2711a,GSS-6(-0.83±0.14,2SD,n=6)and GSD-21(-0.51±0.10,2SD,n=6)could also be used as potential candidate reference materials for comparison of Se isotope compositions and future quality control among different laboratories.The purpose of this study is to improve the method for selenium isotope determination.The data of the Se isotope ratios of reference materials enriches the isotope database,which has positive significance for the application of Se isotopes.The results can not only improve the efficiency and precision of sample analysis,but also extend the application field of Se isotope by reducing the requirements of element concentration in samples. |
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