Low-level Mercury Analysis

Mercury

Mercury 2

Low-level Mercury Analysis

Biogeochemical Analytical Service Laboratory has the capability to provide low-level mercury (Hg) analysis, including total Hg (THg), methyl Hg (MeHg), as well as spiked stable Hg isotope analysis, in all forms of matrices.

Biogeochemical Analytical Service Laboratory currently houses the following instruments for low-level mercury analysis:

Tekran 2600 Automated Total Mercury Analyzer
Tekran 2700 Methyl Mercury Analyzer
Tekran 2750 Methyl Mercury Distillation System
Milestone DMA-80 Direct Mercury Analyzer
Labconco Freezone 12
Elan DRC-e ICP-MS
UV digestor


Methodologies for mercury analysis:

Total Mercury by Cold Vapor Atomic Fluorescence Spectrometry (CVAFS)

Bromine Monochloride (BrCl) is added to the sample container to oxidize all forms of Hg to HgII oxidation state. After a minimum of 12 hours the BrCl is neutralized by addition of Hydroxylamine Hydrochloride (NH2OH*HCl). Following neutralization, Stannous Chloride (SnCl2) is added to the sample to reduce the Hg from the HgII to the Hg0 oxidation state. The Hg0 is purged onto gold-coated glass bead traps (sample). The mercury vapor is thermally desorbed to a second gold trap (analytical) and from that detected by cold vapor atomic fluorescence spectrometry (CVAFS). Samples high in organic matter may require initial pretreatment in an ultra violet (UV) digester to remove the color associated with the organic matter.

Matrices: Water, particulates (on filters), biological Tissue (Fish, invertebrates), plants, soils, sediments

Detection Limits:

Water MDL: 0.05 ng/L Tissue, plant, soil MDL: 0.51 ng/g

Total Mercury by Direct Mercury Analyzer DMA-80

Water or solid samples are dried and then thermally and chemically decomposed in an oxygenated decomposition furnace to liberate the mercury from the samples. The decomposition products are carried via oxygen to the catalytic tube where the mercury is reduced to Hg0 and then trapped on the amalgamator. Any remaining products and interferences are flushed with oxygen gas, then the amalgamator is rapidly heated to release the mercury vapor into the absorbance cells. The mercury is then measured using atomic absorption spectrophotometry.

Matrices: Water, Solid


Methyl Mercury by 2700 Methyl Mercury Analyzer

Distillation:

The water samples are distilled at 127oC with the addition of Ammonium 1-Pyrrolidinecarbodithioate (APDC) and Hydrochloric Acid (HCl). For solid samples such as fish or plant, the samples are digested overnight in Sulfuric Acid, and Potassium Chloride (KCl) and Milli Q water in a Teflon tube. A reference material is used to verify the accuracy of the method. The samples are distilled at 1100C with the addition of APDC and HCl.

Analysis:

Ascorbic Acid is added to distillate. The distillate is transferred in glass vials where the pH is adjusted with Acetate buffer.  Ethylation is done by adding Sodium Tetraethyl Borate (NaTEB).  Purging, trapping and analysis are done in situ by the 2700 Methyl Mercury analyzer.

Matrices: Water, particulates (on filters), biological Tissue (Fish, invertebrates), plants, soils, sediments

Detection Limits:

Water MDL: 0.016 ng/L Tissue, plant, soil MDL: 4 pg/g

If you are interested in any of the above analyzes, please contact Dr. Mingsheng Ma (mingsheng.ma@ualberta.ca) for more information.