Determination of mercury at picogram level in natural waters with inductively coupled plasma mass spectrometry by using 3D printed metal scavengers

Abstract

The determination of ultra-trace concentrations of Hg in natural water samples via preconcentration using 3D printed metal scavenger technique followed by inductively coupled plasma mass spectrometry (ICP-MS) was developed. The determination of Hg in certified reference material ERM-CA615 (groundwater) was performed with high accuracy and precision resulting in recovery of 100 ± 3% and RSD <2.5%, respectively. Selective laser sintering (SLS) 3D printing was used to fabricate the scavengers using a mixture of polyamide-12 powder with thiol-functionalized silica. The preconcentration procedure is based on the adsorption of Hg on the scavenger and followed by elution of the preconcentrated Hg from the filter with 0.3% thiourea in 8% HCl prior to its determination by ICP-MS. A preconcentration factor of 92.8 can be achieved by filtering 495 mL of water followed with the elution step. Very low instrumental detection limit and method detection limit were obtained resulting in 0.013 and 0.037 ng L−1, respectively. The method was applied successfully for the determination of Hg in different lake and river water samples. The developed method is the first preconcentration method enabling simple and accurate determination of Hg in pg L−1 concentrations in natural waters with ICP-MS.