A Potential New Chalcopyrite Reference Material for LA-MC-ICP-MS Copper Isotope Ratio Measurement

A new natural chalcopyrite reference material TC1725 is prepared for in situ Cu isotope measurement by femtosecond laser ablation multi-collector inductively coupled plasma-mass spectrometry (fsLA-MC-ICP-MS). Detailed textural examination and major element determination suggest the TC1725 chalcopyrite grains have no growth rim or zoning. The chalcopyrite grain is homogeneous with respect to Cu isotopes based on a large number of measurements performed by bulk solution nebuliser (SN)-MC-ICP-MS, single-grain SN-MC-ICP-MS and fsLA-MC-ICP-MS. The traditional bulk isotope analyses by SN-MC-ICP-MS yielded a mean delta Cu-65 value of -0.06 +/- 0.03 parts per thousand (2s, n = 132). Randomly selected single chalcopyrite grain of TC1725 determined by SN-MC-ICP-MS without column chromatography gave a mean delta Cu-65 value of -0.06 +/- 0.04 parts per thousand (2s, n = 188). The intermediate measurement precision for four measurement sessions was better than 0.04 parts per thousand (2s), suggesting TC1725 chalcopyrite is suitable as a microanalysis reference material for Cu isotope measurement. The mean delta Cu-65 value determined by fsLA-MC-ICP-MS analyses on different individual chalcopyrite mounts and strips was -0.06 +/- 0.03 parts per thousand (2s, n = 393), consistent with the bulk isotope composition within 4ertainty. The recommended mean delta Cu-65 value for this chalcopyrite reference material is -0.06 +/- 0.03 parts per thousand (2s, n = 132) as determined by bulk SN-MC-ICP-MS.

Automated summary

The newly prepared natural chalcopyrite reference material TC1725 is homogeneous and suitable for microanalysis reference for Cu isotope measurement with good measurement precision. The mean delta Cu-65 value for this chalcopyrite material is consistent and reliable for bulk and single-grain isotope analyses performed by different techniques.