High Precision Measurement of Selenium Isotopic Composition by Hydride Generation Multiple Collector Inductively Coupled Plasma Mass Spectrometry with a 74Se-77Se Double Spike

A method was developed for high precision measurement of selenium isotopes by hydride generator-multiple collector inductively couple plasma mass spectrometry ( HG-MC-ICP-MS) using Se-74-Se-77 double spike and modified thio-cotton purification procedures. Thio-cotton was first used to chemically separate selenium from sample matrix, followed by removing unknown organic matter from thio-cotton using HNO3 + H2O2 for possibly interfering hydride generation. (SeSe)-Se-74-Se-77 double spike allowed us to effectively correct analytical isotope fractionation during sample chemical purification and mass spectrometry measurement. The external reproducibility for standard NIST SRM3149 and MH495, nature sample were 0.1% (2 sigma) and 0.15% - 0.2% (2 sigma) over the course of several months, respectively. Based on the average yield (85%) of Se separation using thio-colton, the minimum quantity of Se needed for isotope analysis was approximately 20 ng. Se isotope ratios was reported relative to NIST SRM3149, house standard delta(82/76)(MH495/RM3149) = -3.44 +/- 0.1)% (2 sigma) which was in agreement with previously published data delta(82/76)(MH495/SRM3149) = -3.04 +/- 0.5% from sample-standard bracketing techniques. Selenium isotopes were measured in several sedimentary samples with a range in delta(82/76) Se between -13.53% and 11.37% relative to NIST SRM3149, these results indicated a wide perspective application of Se isotopes in environmental, geological, agricultural and life field.