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

RATIONALE: 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). METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.