Abstract
A selective method for preconcentration and determination of methylmercury (MeHg) and inorganic mercury (iHg) in natural water samples at the ng L-1 level has been developed. The method involves adsorption of Hg species into a 3D printed metal scavenger and sequential elution with acidic thiourea solutions before ICP-MS determination. Experimental parameters affecting the preconcentration of MeHg and iHg such as the sample matrix, effect of the flow rate on adsorption, eluent composition, and elution mode have been studied in detail. The obtained method detection limits, considering the preconcentration factors of 42 and 93, were found to be 0.05ngL-1 and 0.08ngL-1 for MeHg and iHg, respectively. The accuracy of the method was assessed with a certified groundwater reference material ERM-CA615 (certified total iHg concentration 37±4ngL-1). The determined MeHg concentration was below MDL while iHg concentration was determined to be 41.2±0.5ngL-1. Both MeHg and iHg were also spiked to natural water samples at 5ngL-1 concentration and favorable spiking recoveries of 88-97% were obtained. The speciation procedure was successfully applied to two lake water samples where MeHg and iHg concentrations ranged from 0.18 to 0.24ngL-1 and 0.50-0.62ngL-1, respectively. The results obtained demonstrate that the developed 3D printed metal scavenger-based method for preconcentration and speciation of Hg is simple and sensitive for the determination of Hg species at an ultra-trace level in water samples.
Highlights
Mercury (Hg) and its compounds are highly hazardous pollutants, with organic Hg compounds generally more toxic than their inorganic counterparts
The most common methods used for Hg speciation are chromatographic methods including gas chroma tography (GC) and high-performance liquid chromatography (HPLC) hyphenated to highly sensitive elemental specific detection techniques such as cold vapor atomic fluorescence spectrometry (CV-AFS) and inductively coupled plasma mass spectrometry (ICP-MS)
The analytical performance of the method was evaluated with replicate determinations of quality control (QC) sample, and certified groundwater reference material of ERM
Summary
Mercury (Hg) and its compounds are highly hazardous pollutants, with organic Hg compounds generally more toxic than their inorganic counterparts (iHg). According to the United Nations Environment Programme’s (UNEP) Global Mercury Assessment 2018 report [2], human activities have increased total atmospheric Hg concentrations by about 450% above natural levels, leading to Hg loads in some food webs reaching levels of concern for ecological and human health. Typical concentrations of total Hg in natural water are in the low ng L− 1 range, with MeHg content ranging from only a few percentages up to 30–40% of the total Hg [3,4,5]. Speciation analysis is often challenging due to extremely low concentrations of Hg in non-polluted waters. In addition to chromatographic methods, non-chromatographic methods can be used to separate Hg species based on the different chemical and/or physical properties [5]
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