Precise/ Small Sample Size Determinations of Lithium Isotopic Compositions of Geological Reference Materials and Modern Seawater by MC‐ICP‐MS

The Li isotope ratios of four international rock reference materials, USGS BHVO‐2, GSJ JB‐2, JG‐2, JA‐1 and modern seawater (Mediterranean, Pacific and North Atlantic) were determined using multi‐collector inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS). These reference materials of natural samples were chosen to span a considerable range in Li isotope ratios and cover several different matrices in order to provide a useful benchmark for future studies. Our new analytical technique achieves significantly higher precision and reproducibility (< ± O.3%o 2s) than previous methods, with the additional advantage of requiring very low sample masses of ca . 2 ng of Li.