GeoAnalytical Laboratory--Radiogenic Isotope Facility

The Department of Geology at Washington State University has been recently equipped with a ThermoFinnigan Neptune MC-ICPMS. The Neptune is a doubly focusing, plasma source multicollector mass spectrometer that offers high elemental sensitivities (~80V/ ppm Hf at an aspiration rate of 0.05 ml/min). The Neptune has nine movable Faraday collectors and one high-sensitivity ion-counting electron multiplier. This collector configuration has wide-ranging utility in measuring high precision isotope ratios in a variety of isotopic systems including both Lu and Hf. We are now routinely analyzing Hf isotopes with high precision and accuracy: 176Hf/177Hf = 0.282144???11(1), 178Hf/177Hf = 1.467209???35(4), 180Hf/177Hf = 1.886678???95 (11); 2 SD on last 79 standard runs over the last year (2 SE in parentheses); no efficiencies or secondary corrections applied. The 176Hf/177Hf of the standard generally reproduces for each analytical session (1 day) within a total range of 0.000010. Similar precision and accuracy is routinely attainable with Nd isotopic measurements.

To support the Neptune, we have a HEPA-filtered ~900 ft3 class 1000 clean laboratory that is used to perform chemical separations of Lu-Hf, Sm-Nd, Rb-Sr, U-Th-Pb, and HFSE using column chromatography. This lab is now fully functional with low-blank distilled water, quartz and Savillex stills for generating low-blank HCl, HNO3, and HF acids, thoroughly calibrated mixed Lu-Hf, Sm-Nd, and Rb-Sr spikes, and ion-exchange columns for Lu-Hf, Rb-Sr, Sm-Nd, and U-Th-Pb separations.