Evaluation of electrothermal vaporization for sample introduction aiming at Cu isotopic analysis via multicollector-inductively coupled plasma mass spectrometry

Abstract

A new method for Cu isotopic analysis was developed using a commercially available electrothermal vaporization (ETV) device coupled to multicollector-inductively coupled plasma mass spectrometry (MC-ICP-MS).The method demonstrated potential for the isotopic analysis of microsamples (e.g., 5 μL) in a biological context. For example, Cu isotopic analysis of NIST 3114 (diluted to 1 mg L−1 Cu) using self-bracketing provided average δ65Cu values of 0.00 ± 0.17‰ (2SD, n = 10) and internal precision values of 712 ppm. In order to achieve this level of accuracy and precision, it is critical to properly deal with the short transient signals generated by the ETV-MC-ICP-MS, which implies using point by point calculations and time lag detector correction (TDC), as well as a criterion to reject potential outliers.The results of this technique were compared with the results obtained via femtosecond-laser ablation-MC-ICP-MS using the same pre-treated serum samples. No significant differences were observed among the results obtained in both cases, while external precision was 0.26‰ for ETV-MC-ICP-MS and 0.24‰ for fs-LA-MC-ICP-MS, expressed as median value of 2SD (n = 27), further proving the usefulness of the approach proposed in this context, as the use of ETV results in a more straightforward approach.