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DMA-80 (Direct Mercury Analyzer)

• Built-in 40 position autosampler for unattended, high throughput of samples with quartz or metal boats
• Dual measuring cells for extended analysis range, up to 1000 ng
• Built-in Atomic Absorption Spectrophotometer uses 254 nm wavelength for Hg analysis
• Terminal 1024 allows easy manipulation of the control software via keyboard and mouse or touch screen monitor
• Analytical balance for automatic sample weight data transfer
• Easy data transfer by EasyDOC Windows-based software

The DMA-80 permits direct analysis of trace level mercury in several matrices in a wide variety of industries and laboratories:

• Solids: sediment, soil, sludge, food/feed, plant and animal tissues, coal, oil, fish, cement, paints, wood, plastic.
• Liquids: wastewater, beverages, biological fluids.
• Environmental, agriculture, petrochemical, food and feed, power plant, mines and resources laboratories.

Quartz Sample Boats

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For automated Direct Mercury Analysis of aqueous samples

If you are currently using our nickel sample boats, then you know that you cannot process aqueous samples in the DMA-80's autosampler. Dilute nitric acid must be used to stabilize the Hg in solution, to prevent its volatilization. The downside of this practice is that when the sample is introduced into the Ni boat, after a few minutes, the nitric acid starts reacting with the nickel, generating hydrogen gas. During the reaction, Hg is freed up and volatilized along with H₂.

As a solution to this problem, Milestone now offers quartz sample boats. Quartz is inert to acids, and will not generate any side reactions. This allows you to use the autosampler with aqueous samples.

The simplicity and speed of the DMA-80

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Rapid determination of Hg in fresh salmon

1 - A representative sample is taken and homogenized		2 - The sample is weighed on an analytical balance interfaced with the DMA-80		3 - A series of samples is placed in the built-in autosampler

4 - After 5 minutes the first result is obtained

Principle of operation

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Solid or liquid 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 quantitation. The mercury content is determined using atomic absorption spectrophotometry at 254 nm.

The graphic shows a typical peak profile resulting from analysis.
The 1st peak corresponds to the long pathlength flow cell and Hg content up to 20 ng. The instrument determines the absolute amount of Hg (normally expressed in ng), 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 Portability of the Direct Mercury Analyzer

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The DMA-80 performs well not only in the perfectly clean lab environment, but in the field as well. The most recent proof of this statement is Milestone's participation in a major demonstration project held by the U.S. EPA in Oak Ridge, Tennessee. The EPA had organized a study to validate field Hg analyzers. The project took 3 full days of running soil samples in the field from 7:30 in the morning to 7:30 in the evening.

The instrument was set up in a tent outdoors, five feet away from two buildings that contained explosives, PCBs, chemical and biological warfare agents, and some radioactive materials. There also were hurricanes nearby at the time. The rain practically never let up during the entire project. The tent that was used to protect the instrument and analyst had only a ceiling and 2 walls. The instrument was kept inside a van at times to protect it from dripping water. A total of 170 samples were run, varying from 1 ppb to 50 ppm. The data is available from Milestone upon request, or directly from the EPA.

2007 © Milestone Inc. :: email: mwave@milestonesci.com call: 866-995-5100