Automated Analyte Separation by Ion Chromatography Using a Cobot Applied to Geological Reference Materials for Li Isotope Composition

The demand for large and reliable data sets on isotopic composition has increased in geochemistry and environmental sciences over recent years. We present an automated ion chromatographic separation method using a robotic pipetting arm, termed 'ChemCobOne', to reduce sample separation time. Its performance was tested for lithium isotope separation in geological reference materials using a single-step separation with HCl (0.2 mol l(-1)) and a 2 ml resin volume. This refined lithium purification method does not forfeit precision, accuracy or purity compared with manual sample processing. In addition, a delta Li-7 value for NASS-6 of 30.99 +/- 0.50 parts per thousand (2s) (95% CI = 0.14 parts per thousand, n = 44) was determined and the first delta Li-7 values for the granite rock reference material GS-N (-0.57 +/- 0.25 parts per thousand (2s), 95% CI = 0.15 parts per thousand, n = 15), and for the soil reference material NIST SRM 2709a (-0.37 +/- 0.67 parts per thousand (2s), 95% CI = 0.15 parts per thousand, n = 63) are proposed.