AN ADAPTED COLUMN CHEMISTRY PROCEDURE FOR SEPARATION OF FE, CU AND ZN FROM GEOLOGICAL MATRICES, AND NATURAL ZN ISOTOPIC VARIATIONS IN GEOLOGICAL STANDARD REFERENCE MATERIALS BCR-027, BCR-030 AND NOD-P-1

The aims of this study were to refine previously published column chemistry procedures to achieve optimum elution-profile and recovery when analysing geological materials, and to measure natural Zn, Cu and Fe isotope variations in a range of geological standard reference materials (SRM). High analyte ratios (e.g. Fe/Cu) are a problem when analysing geological materials, especially ore minerals. High element concentrations – particularly P and Fe – relative to trace analytes cause premature elution, resulting in reduced recovery and contamination of other element fractions. Our improved chromatography gives high-yield (>99%) elemental separates for Fe, Cu and Zn, free from significant major and minor elements. Analyte purity has been verified by ICP-AES, isobaric interferences by three-isotope plots on Fe and Zn, and non-spectral interferences by ICP-MS sensitivity comparison. Data quality has been assessed using industrial single-element solutions, geological SRM, in-house and international isotopic standards, and inter-laboratory comparison. Isotope analysis for SRM samples BCR-027 (blende ore), BCR-030 (calamine ore), and NOD-P-1 (ferromanganese nodule) has yielded ä66Zn values (relative to in-house standard IMP ZnTM) of 0.248 ±0.07‰ (2s), -0.147 ±0.115‰ (2s), and 0.933 ±0.05‰ (2s) respectively. Long-term reproducibility, using industrial standard Romil Zn, is good (±0.045‰ per amu, n=7, over two years). I aim also to present further Zn, Fe and Cu data for SRM samples BCR-027, NOD-P-1, BCR-1 and SU-1, as well as preliminary results for isotopic studies of the Cumbrian hematite deposits.