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87Sr/86Sr analysis of < 10ng NBS 987 on Phoenix TIMS
Introduction High sensitivity Sr isotope ratio measurements using TIMS can be used to evaluate sub millimetre isotope variations in zoned minerals and fluid inclusions. Sample sizes of a few nanograms of Sr are generated and so “every ion counts” to get a precise measurement. In this preliminary study a Phoenix TIMS was used to analyse…
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Mass Fractionation behaviour of U isotopes during Thermal Ionization, the potential for mass fractionation correction using double spike
Introduction Until recently it was assumed that the terrestrial 235U/238U was 137.88. However high precision 235U/238U measurements using ICP multi collector mass spectrometers1 as well as double spiked TIMS have shown small variations in 235U/238U at the 1- 2 per mil level. In uranium ores these variations are possibly due to changes in environmental redux…
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High precision Os isotope ratio measurements using Phoenix X62 TIMS
Introduction The study of Osmium isotopes is an important tool in geochemistry and cosmochemistry (e.g. Shirey and Walker 1998, Brandon et al. 2006, Ravizza and Turekian 1992). Side box 1 provides background on the two Os isotope systems of interest. Whilst 187Os/188Os ratios can vary by several percent, the variation in 186Os/188Os is far smaller…