Influence of room temperature on magnesium isotope measurements by multi-collector inductively coupled plasma mass spectrometry.

Abstract

We observed that the accuracy and precision of magnesium (Mg) isotope analyses could be affected if the room temperature oscillated during measurements. To achieve high-quality Mg isotopic data, it is critical to evaluate how the unstable room temperature affects Mg isotope measurements by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). We measured the Mg isotopes for the reference material DSM-3 using MC-ICP-MS under oscillating room temperatures in spring. For a comparison, we also measured the Mg isotopes under stable room temperatures, which were achieved by the installation of an improved temperature control system in the laboratory. The δ26 Mg values measured under oscillating room temperatures have a larger deviation (δ26 Mg from -0.09 to 0.08‰, with average δ26 Mg=0.00±0.08‰) than those measured under a stable room temperature (δ26 Mg from -0.03 to 0.03‰, with average δ26 Mg=0.00±0.02‰) using the same MC-ICP-MS system. The room temperature variation can influence the stability of MC-ICP-MS. Therefore, it is critical to keep the room temperature stable to acquire high-precision and accurate isotopic data when using MC-ICP-MS, especially when using the sample-standard bracketing (SSB) correction method.