Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, 1 University Station C1160, Austin, TX-78712-0254, United States Chemical Geology (2015), V396, pp112–123, doi: 10.1016/j.chemgeo.2014.12.014 High precision Os isotopicmeasurement using N-TIMS: Quantification of various sources of error in 186Os/188Os measurements Rudra Chatterjee and John C. Lassiter The 190Pt–186Os system could be useful to study a number of different geologic processes. Over the last decade, this system has received considerable attention owing to its potential to detect core–mantle signatures in plume-derived lavas. Additionally, this system may also be useful as a proxy for melt depletion, examining the role of pyroxenites/sulfides in mantle melting and for dating of Platinum Group Element (PGE) based ores. The total natural variation of 186Os/188Os is limited (~150 ppm in the mantle), which thus requires extremely high levels of accuracy and precision to discern natural variations. 186Os/188Os ratios were measured in laboratory standards and natural samples to examine and quantify the sources of error affecting high precision 186Os/188Os measurements and a set of refined analytical procedures to minimize and reduce these various sources of error were recommended.