Non-chromatographic screening method for the determination of mercury species: application to the monitoring of mercury levels in Antarctic samples

Abstract

A simple non-chromatographic method for the determination of mercury (Hg2+), methylmercury (MeHg+), dimethylmercury (Me 2Hg), and phenylmercury (PhHg+) employing atomic fluorescence spectrometry (AFS) as detection technique was developed. Mercury species showed a particular behavior in the presence of several reagents. In a first stage SnCl2 was employed for Hg2+ determination; in a second step, [Hg2+ + PhHg+] concentration was determined using SnCl2 and UV radiation. MeHg+ decomposition was prevented adding 2-mercaptoethanol. In a third stage, [Hg2+ + PhHg+ + MeHg+] concentration was determined using K 2S2O8. Finally, the four species were determined employing NaBH4. Reagents concentration and flow rates were optimized. The extraction technique of mercury species involved the use of 2-mercaptoethanol as ion-pair reagent. The limits of detection for Hg 2+, PhHg+, MeHg+, and Me2Hg were 1, 40, 68, and 99 ng L-1 with a relative standard deviation of 1.5, 3.1, 4.7 and 5.8%, respectively. Calibration curve was linear with a correlation factor equal to 0.9995. The method was successfully applied to the determination of the mercury species in two Antarctic materials: IRMM 813 (Adamussium colbecki) and MURST-ISS-A2 (Antarctic Krill).