A Case Study of Spectral and Non‐Spectral Interferences on Copper Isotope Measurements by Multi‐Collector ICP‐MS (Wet Plasma)

Abstract

Mathematical modelling was combined with experimental Cu isotope measurements to demonstrate the effect of the sample matrix in changing the absolute and relative abundances of spectral interferences from Ti and Cr species. This unforeseen non-spectral effect, evidenced by variable inaccuracies of the different Zn-normalised Cu isotope ratios, was investigated by comparing real sedimentary samples and artificial solutions intended to match the Cu:Ti:Cr ratios of the real samples after (one-or two-step) chromatographic processing. Artificial solutions showed positive bias in δ 65 Cu X/Y with the magnitude depending on (1) the 6X Zn/ 6YZn ratio used for normalisation, (2) the Ti/Cu ratio and (3) the transmission Accepted Article

Combined Separation of Cu, Fe and Zn from Rock Matrices and Improved Analytical Protocols for Stable Isotope Determination

“…Of the matrix‐based Ti‐, Cr‐ and V‐O + and ‐OH + interferences, the titanium‐based isobars represent the most likely source of error (Petit et al . ). In theory, all of the Ti, Cr and V should be removed in the first 4 ml of the matrix elution.…”

“…The measured 48 Ti 16 O + / 48 Ti + ratio is of the order of 0.001–0.002 (0.1–0.2%) for typical wet plasma conditions (Petit et al . ). We confirmed this oxide production rate through progressive addition of Ti to a pure 300 ng ml −1 Zn solution at 48 Ti/ 64 Zn ratios of 0.0007, 0.007 and 0.07.…”

“…The effects of Ti‐ and Cr‐based isobars, particularly 48 TiO + on the Zn masses are well‐documented, leading to variability on the Zn‐corrected δ 65 Cu of up to several per mil (Petit et al . , ), interferences that do not befall Ni. The 64 Zn 1 H + interference on 65 Cu under wet plasma conditions (Mason et al .…”

The estuarine geochemical reactivity of Zn isotopes and its relevance for the biomonitoring of anthropogenic Zn and Cd contaminations from metallurgical activities: Example of the Gironde fluvial-estuarine system, France

“…Instrumental mass bias was corrected by sample standard bracketing and external normalization to a common Cu standard (Mason et al, 2004;Petit et al, 2008b), assuming an exponential law of mass fractionation. The measurement of several Cu-normalized Zn isotope ratios allowed checking for massdependent fractionation and potential isobaric interferences on Zn masses (Petit et al, 2013a). Samples were typically run in triplicate and bracketed by two standards.…”

Response of copper concentrations and stable isotope ratios to artificial drainage in a French Retisol

“…For soil samples, the column purification was repeated once to gain matrix-clean Cu fractions (Bigalke et al, 2011;Petit et al, 2012). After complete separation, the purified fractions were evaporated to dryness and digested with concentrated HNO 3 and H 2 O 2 .…”