DMA-80 Direct Mercury Analyzer

Technical Details

The DMA-80 Direct Mercury Analyzer performs thermal decomposition + catalytic reduction + amalgamation + desorption + atomic absorption spectroscopy to rapidly treat and analyze solid or liquid samples for mercury. Milestone's modern DMA-80 system is optimized for solid sampling, so it accomplishes all of the above steps in one integrated system. It gives mercury analysis results in about 5 minutes (per sample) with no sample pretreatment or waste generation.

Instrument Configuration

The DMA-80 Direct Mercury Analyzer consists of the following components:

• Autosampler with 40-position sample tray
• Drying/decomposition furnace
• Catalyst tube
• Amalgamator
• Unique dual-cell cuvette block in series with delay cell
• Hg source lamp and detector
• Hg trap
• Touch-screen controller with keyboard & mouse; preloaded Windows 98 and DMA-80 software

Sequence of Operation

Liquid or solid samples are introduced into the DMA-80 Mercury Analyzer. Prior to combustion, the sample is initially dried in an oxygen stream passing through a quartz tube located inside a controlled heating coil. The combustion gases are further decomposed on a catalytic column at 750 °C. Mercury vapor is collected on a gold amalgamation trap and subsequently desorbed for quantitation. Mercury content is determined using atomic absorption spectrometry at 254 nm, and the results are displayed using a Pentium-based control terminal.

Technical Specifications

Instrument Control	Touch-screen controller
Instrument Optics	Single beam spectrophotometer with sequential flow through of measurement cells
Light Source	Low-pressure mercury vapor lamp
Wavelength	253.65 nm
Interference Filter	254 nm, 9 nm bandwidth
Detector	Silicon UV photodetector
Detection Limit	0.005 ng Hg
Working Range (with automatic switch-over)	Low range: 0–20 ng Hg High range: 20–1,000 ng Hg
Reproducibility	< 1.5%
Sample Treatment	Completely programmable
Sample Introduction	Built-in 40-position autosampler
Calibration	Performed with Std. Ref. Materials in liquid or solid form
Max. Liquid Sample Volume	1,500 μL
Max. Solid Sample Weight	2,000 mg
Carrier Gas	Oxygen
Input Pressure	4 bar (60 psig)
Flow Rate	~ 165 mL/min
Power	110 V / 60 Hz
Dimensions	29 x 19 x 9 in.
Weight	56 kg (123 lbs.)

Accuracy

Mercury recoveries obtained using the DMA-80 analyzer, and certified values for eight Standard Reference Materials, are tabulated below:

Sample	#	Ref. Value ppm (mg/kg)	DMA-80 ppm (mg/kg)
BCR CRM 184 Bovine Muscle	5	0.0026 ± 0.0006	0.0028 ± 0.0008
NIST SRM 8433 Corn Bran	2	0.003 ± 0.001	0.004 ± 0.001
BCR CRM 150 Skim Milk Powder	2	0.0094 ± 0.0017	0.0097 ± 0.0005
BCR CRM 185 Bovine Liver	2	0.044 ± 0.003	0.044 ± 0.001
NIST SRM 1566a Oyster Tissue	12	0.064 ± 0.007	0.064 ± 0.004
BCR CRM 151 Skim Milk Powder	10	0.101 ± 0.010	0.093 ± 0.005
BCR CRM 278 Mussel Tissue	9	0.188 ± 0.007	0.181 ± 0.009
Lyophilized human blood (1)	1	0.004	0.0033

Precision

Data obtained from 12 analyses of NIST SRM 1566a oyster tissue is reported in the table below:

NIST SRM 1566a Oyster Tissue Ref. Value: 0.064 ± 0.007 ppm (mg/kg)
DMA-80 Analysis	Concentration (mg/kg)
1	0.067
2	0.064
3	0.068
4	0.067
5	0.064
6	0.064
7	0.063
8	0.063
9	0.064
10	0.062
11	0.063
12	0.061

Average Value	0.064
sd	0.002
rsd	0.033
cv%	3.32%

Validation

The DMA-80 Direct Mercury Analyzer provides results that are not only as good as traditional Cold Vapor methods, but—in the experience of many of our customers—often more accurate and more precise.

For supporting bar graphs, see this page: Direct Mercury Analysis Gives You Better Data.

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Mercury: See an overview, or view the DMA-80 product details, the fundamentals of mercury analysis, or see our resource library of methods, application notes, and articles.
General: Go to the Milestone front page, or send us an inquiry.