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Chemical Analyses

 

 

The analytical facilities at the Large Lakes Research Station are housed in specialized laboratories. These include a total mercury, methyl mercury, trace element, general sample preparation, water supply, and clean room laboratories. These laboratories support our Mass Balance Modeling Studies as well as original studies of birds, fish, and sediment. All analytical laboratories have been renovated in the last several years.

Instrumentation for total mercury analyses includes a Milestone DMA-80 and LECO AMA-254 analyzers. There is no sample pretreatment using these instruments. The introduced sample is thermally decomposed to a gaseous form, passed through an oxygen-rich catalyst to remove interferences, sequestered on a gold amalgam, thermally released from the amalgam, and passed through a dual-cell, atomic-absorption spectrometer.

milestone DMA-90 analyzer
Milestone DMA-90 Analyzer
LECO AMA-254 analyzer
LECO AMA-254 Analyzer

 

 

 

 

 

 

 

 

 

 

Agilent 6890 capillary gas chromatograph
Agilent 6890 capillary gas chromatograph

For methyl mercury analyses, an Agilent 6890 capillary gas chromatograph coupled with a PS Analytical 10.750 Hg speciation atomic fluorescence spectrometer is used.  Samples are dissolved using a KOH/H20 solution.  The methylmercury is extracted into dichloromethane using acidic KBr/CuSO4.  The methylmercury/dichloromethane extract is concentrated into Na2S2O3 and concentrated further by extracting back into dichloromethane using the bromide derivative.

chromatograph and spectrometer
Perkin-Elmer ELAN DRC-e ICP-MS Spectrometer

Trace element analyses are performed on a Perkin-Elmer ELAN DRC-e ICP-MS Spectrometer housed in a controlled environment adjacent to a class 100 clean room.  Acid-preserved water samples are run directly on the instrument.  Sediment samples are freeze-dried, ground, and extracted using microwave digestion.  

Specialized equipment used in support of all sample preparation and analyses includes a Virtis freeze-dryer, a Millipore Super-Q water system receiving feed from a Millipore reverse osmosis system, a CEM MARS 5 microwave digester, and a Retsch MM301 mixer mill.

 

 

freeze dryer
Virtis freeze-dryer
water system
Millipore Super-Q water system
microwave digester
CEM MARS 5 microwave digester
mixer mill
Retsch MM301 mixer mill


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