 Principle of operation
Solid, liquid or gas samples are weighed and introduced into the sample boat.
The sample is initially dried and then thermally decomposed in a continuous flow of oxygen. Combustion products are carried off and further decomposed in a hot catalyst bed.
Mercury vapors are trapped on a gold amalgamator and subsequently desorbed for quantization.
The mercury content is determined using atomic absorption spectrophotometry at 254 nm.
Typical applications that the DMA-80 is used for include environmental, geochemical, petrochemical, food and feed, clinical and polymer samples.
Handling of a second sample tray: a clear benefit for the instrument sample throughput!
Moreover, while the DMA-80 is running, the software allows the user to prepare a second set of 40 samples on a separate sample tray.
The main advantage associated with this new feature is the capability to run the DMA-80 continuously, without any interruption; while one tray is in use, the second one can be prepared. Therefore, its productivity becomes basically unlimited.
You can choose between the two version of the DMA-80: DMA-80 standard version and Tri-cell DMA-80.
Further information are reported in the below chart.
DMA-80
The standard version of the Milestone DMA-80 is equipped with two measuring cells, a mercury lamp and detector for mercury detection in different sample.
 The graphic on the right shows a tipycal peak profile resulting from the determination of 1ng of Hg.
The 1st peak corresponds to the long pathlength flow cell and measures Hg contents up to 20 ng.
The instrument determines the absolute amount of Hg and then the software calculates its concentration in the sample.
The 2nd peak corresponds to the short pathlength flow cell and Hg content in the range of 20-1000 ng.
The software measures the height, the half width and the area of the absorbance peak, which assists in both method development and troubleshooting.
| The DMA-80 working range |
DMA-80 detection limit |
Low range: 0-20 ng Hg
High range: 20-1000 ng Hg |
0.005 ng Hg |
Tri-cell DMA-80
The Milestone’s Tri-cell DMA-80 combines an innovative tri-cell measuring system of mercury with a new dual optical path spectrophotometer. It is equipped with a further cell (Cell 0) and with 2 Silicon UV Photodetectors.
These improvements enable working at lower mercury concentration and open the possibility to carry out previously unachievable applications.
The same quantity of mercury can be measured three times using three different sensitivities resulting in a dynamic range that spans at least 6 orders of magnitude.
| Wider working range |
Tri-cell DMA-80 detection limit |
Low range: 0-10 ng Hg
Medium range: 10-20 ng Hg
High range: 20-1000 ng Hg
|
0.0015 ng Hg |
Main Advantage
Better Sensitivity: standard Solution with a mercury concentration of 0.2 μg/kg (ppb)
The absorbance value (ranging from 0,0077 to 0,0079) and the result is extremely accurate and precise, with average of 0,22 μg/kg (ppb) and RSD of 2,48%. Thanks to this new measuring system, it is now possible to:
- Determine mercury at lower concentrations
- Perform a wider range of applications
Sorbent Traps
 Sorbent traps are available for the Milestone DMA-80 to measure the mass concentration of Mercury in gases, including elemental Mercury (Hg0) and oxidized forms of Mercury (Hg+2) in micro-grams per dry standard cubic meter (μg/dscm).
Gases are collected onto the sorbent tubes by specific devices first.
At the completion of the sampling process, the sorbent tubes are directly placed on the DMA-80 auto-sampler and analyzed.
Benefits
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» High quality analysis |
» Low mercury effect |
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» High recovery > 98.5 % at 1000 ng |
» High recovery for both Hg° and Hg+² forms |
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» High recovery in presence of moisture |
» Reusable sorbent traps |
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» Easy to use: simply place it on the autosampler |
» Best quality-price |
Gas Kit
A new module for the determination of mercury in gases is available for the DMA-80!
Gas samples are collected by a syringe or by Tedlar gas sampling bags, and then directly introduced in the DMA-80.
A schematic representation of the entire process is shown below.
The gas kit consists of an injection block and a vacuum pump, which allow the flowing of the sample through the DMA-80 furnaces, amalgamator and spectrometer.
Benefits
» Direct mercury determination at trace level in gases
» Fast analysis: approximately 3 minutes per sample
» Wide dynamic range: from 0.015 to 1200 μg/cubic meter
» Ease of use
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