Mercury determination in bioresorbable calcium phosphate using a new electrothermal vaporization system coupled to ICP-MS

Abstract

A direct solid sampling method was developed for determining mercury in bioresorbable calcium phosphate-based materials by electrothermal vaporization (ETV) coupled to an inductively coupled plasma mass spectrometry (ICP-MS) instrument. The ETV system is based on fast sample heating using a halogen lamp enclosed in a glass chamber. The heating program comprises only a vaporization step (10 s) followed by a cooling step (120 s) when a solid sample was analyzed. An additional step of 20 s at 80 °C was necessary when aqueous solutions were used for calibration. Mercury was vaporized at a relatively low temperature (650 °C) without co-vaporizing the main matrix (more than 95% of the matrix remains in the lamp dimpled cavity). External calibration with aqueous reference solutions deposited on the sample residue was used for Hg quantification. The accuracy of the proposed method was evaluated by certified reference material analysis (MESS-3) and by pneumatic nebulization ICP-MS (NEB-ICP-MS), and no statistical difference was observed between the results. Relatively high masses (up to 10 mg) can be analyzed without interferences. The limit of quantification (0.2 ng g⁻¹) by ETV-ICP-MS was lower than that by NEB-ICP-MS (60 ng g⁻¹), the precision was better than 15% and the sample throughput was 20 per hour. Therefore, the proposed low-cost ETV system is attractive for determining Hg at the ultra-trace level in biomaterials and can be used for routine analyses.