I'm a biologist working on my graduate thesis project that involves comparing the elemental signature in otoliths (fish ear bones) to concentrations of the same elements found in water. In particular, I am looking at Strontium. I have a water concentration of Sr at .008g/L, and I need to convert that to micro-moles/mole. Ive been searching through old texts and on the internet for methods on how to do this, yet I haven't found anything. Its been several years since Ive taken chemistry, though I still recall how to calculate molar concentration, but I can't figure out how convert that to a mole fraction. Any help on this would be appreciated. And/or if you have useful links or titles to credible resources that would be helpful as well.