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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 δ65Cu value of −0.06 ± 0.03‰ (2s, n = 132). Randomly selected single chalcopyrite grain of TC1725 determined by SN‐MC‐ICP‐MS without column chromatography gave a mean δ65Cu value of −0.06 ± 0.04‰ (2s, n = 188). The intermediate measurement precision for four measurement sessions was better than 0.04‰ (2s), suggesting TC1725 chalcopyrite is suitable as a microanalysis reference material for Cu isotope measurement. The mean δ65Cu value determined by fsLA‐MC‐ICP‐MS analyses on different individual chalcopyrite mounts and strips was −0.06 ± 0.03‰ (2s, n = 393), consistent with the bulk isotope composition within uncertainty. The recommended mean δ65Cu value for this chalcopyrite reference material is −0.06 ± 0.03‰ (2s, n = 132) as determined by bulk SN‐MC‐ICP‐MS. [ABSTRACT FROM AUTHOR]

In this study, two new laboratory reference solutions for testing Cu isotopic composition were established and investigated. Two commercially available pure copper products, copper plate and copper wire, were dissolved in 1000-ml Teflon® bottles, to produce 200 μg ml−1 stock solutions (hereafter referred to as NWU-Cu-A and NWU-Cu-B), and cryogenically stored. The Cu isotopic compositions of the two samples were determined in three different laboratories using multi-collector inductively coupled plasma-mass spectrometry, and the Cu isotopic compositions obtained from the standard-sample bracketing method were consistent within the two standard deviation (2 s) range. The Cu isotopic compositions of the NWU-Cu-A and NWU-Cu-B standard solutions were δ65Cu = +0.91 ± 0.03‰ (2 s, n = 42) and δ65Cu = −0.05 ±0.03‰ (2 s, n = 49), respectively, relative to the reference material NIST SRM 976. [ABSTRACT FROM AUTHOR]