Determination of inorganic and total mercury by flow injection vapor generation atomic absorption spectrometry using a W-coil atomizer

Abstract

A tungsten coil (150 W, 15 V) was used as the atomizer for the proposed Flow Injection Vapor Generation Atomic Absorption Spectrometry (FI-VGAAS) system to determine inorganic mercury and total mercury concentrations. In the proposed method inorganic mercury was measured when the W-coil is at room temperature and total mercury was measured when the W-coil temperature was set to 500 °C. The organic mercury concentration was calculated by subtracting the inorganic mercury concentration from the total mercury concentration. The calibration graphs were linear up to 100 ng ml⁻¹. Limit of detection (LOD) values for inorganic mercury and methyl mercury were 0.60 ng ml⁻¹ and 0.89 ng ml⁻¹ respectively. The precision of the method in terms of RSD was between 2–3%, and the sampling frequency was 100 h⁻¹. In order to validate the proposed method, known concentrations of methyl mercury and inorganic mercury were spiked into deionized water and tap water samples. Certified reference materials (CRM) IAEA-085 and NRC DOLT-3 were analyzed after microwave assisted extraction with 6.0 mol l⁻¹HCl solutions. Both inorganic mercury and methyl mercury concentrations were in agreement with the certified values.