The Washington University Isotope Geochemistry Laboratory led by Frédéric Moynier measures the isotopic compositions of terrestrial, lunar and meteoritic materials to understand 1) the chronology of the first million years of the Solar System, 2) the physical and chemical processes which have modified these materials, and 3) the nucleosynthesis and the stellar environments at the birth of our Solar System. To reach this goal, we use high precision mass spectrometry associated with chemical purifications in ultra-clean chemistry lab.