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RA-915 Portable Mercury Analyzer with
PYRO-915 pyrolyzer
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Atomic absorption spectrometry
Direct atomic absorption mercury determination (without any pre-treatment
procedures) in the samples with complex matrix (foods, vegetation,
oil and its products, soils, sediments, various biological materials)
is complicated by presence of organic compounds. When such samples
are atomized much smoke is produced and practically in all cases
the total absorption in the cell is out of the working range of
the spectrometer. Using a spectrometer with background correction
- Zeeman atomic absorption mercury spectrometer RA-915+ and a
developed two-chamber catalyst atomizer (PYRO-915), the
direct mercury determination problem is solved.
After inserting the sample in the first chamber of the atomizer
it is heated up to 800 C (all mercury compounds are known to be
dissociated at such temperatures). Less volatile mercury compounds
are dissociated but more volatile species, e.g. mercury organic
compounds, can leave the first chamber as compounds during warming
up of the chamber. In addition presented organic compounds of
the matrix originate much smoke and variously compounds, which
are able to produce strong background absorption in the analytical
cell. All products are transported from the first chamber to the
second one by the carried gas (in our case it is air). The second
chamber is continuously heated about 800 C. There, all mercury
compounds are dissociated and smoke and interference compounds
are burst producing mostly carbon dioxide and water. Zeeman corrector
of the spectrometer eliminates the rest background absorption.
The catalyst improves the efficiency of oxidation and dissociation
in the second chamber.
- Unique direct mercury determination (no pretreatment procedures
required) in organic samples at the level of few mg/kg which
allows assaying practically all substances with the detection
limit much lower than mercury background content
- Mercury determination without its preliminary accumulation
on a gold trap
- Broad dynamic measurement range: 3 orders of magnitude without
diluting the test.
- Large optical length of analytical cell (40 cm)
- Heated windows of the analytical cell which rules out its
contamination even for a sample with a high content of organic
substances
- Monitoring the background absorption during measurement allows
effective selection of the permissible weight of oil and petrol
hydrocarbon samples of any composition, thereby avoiding analysis
errors.
- There are no cold sections in the gas duct between the atomizer
and analytical cell
- Possible use of oxygen along with air for afterburning organic
substances
- No need for compressed oxygen or other gas cylinders
- Visualization of mercury output from the sample, user-friendly
computer interface
- Time-stable calibration coefficient after system heating
- Calibration coefficient is set using standard mercury-containing
sample of any composition
The validity of the method is proved by the agreement between
the measured and certified concentrations in various standard
complex-matrix samples (see the table below). Note the excellent
consistency of the method: the discrepancies between concurrent
measurements do not exceed 10% for different sample weights.
| Reference material |
Iass,
mg |
Measured value,
ppb |
Certificate
value, ppb |
Deviation,
% |
| NIST 1630a (Coal) |
60
140 |
99
92 |
105±23 |
-9 |
| DOLT-2 (Fish liver) |
50
110 |
1860
2070 |
2140±240 |
-8 |
| DORM-1 (Fish) |
50
100 |
860
780 |
798±74 |
+4 |
| IAEA 140 (Sea plant) |
80
170 |
28
32 |
29±7 |
0 |
| BCR-150(Dry milk) |
52
96
109 |
8.4
7.9
7.9 |
9.4±1.7 |
-14 |
| BCR-184(Beef) |
29
59
100 |
2.3
2.5
3.1 |
2.6±0.6 |
0 |
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A table shows analytical features of
the developed system for biological samples. It is seen from
the table that the detection limit (DL) is lower than the
Threshold Limit Value (TLV) of mercury contents accepted in
Russia (e.g. for fish the DL is lower than AL in a factor
of 30). In this case, a representative sample weight of more
than 100 mg is ensured. This Method has also a wide dynamic
range from 0.5 to 10 000 ppb
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| Samples |
TLV, ppb |
DL, ppb |
SW, mg |
| Blood |
50 |
0,5 |
300 |
| Hair |
5000 |
2 |
120 |
| Nail |
|
2 |
120 |
| Urine |
10 |
0,5 |
300 |
| Fish |
300-700 |
300 |
0,5 |
| Bread |
10 |
>300 |
0,5 |
| Cheese |
30 |
120 |
2 |
| Sausages |
30 |
300 |
0,5 |
| Tea |
100 |
100 |
2 |
| Sugar |
10 |
40 |
5 |
| Chocolate |
100 |
100 |
2 |
| Vegetables,
(fruits) |
20 |
>300 |
0,5 |
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| Specifications
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Sample weight |
50-300 mg |
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Upper limit of the measurement range of concentration
for a 20 mg sample |
3-5 mg/kg |
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Time for one measurement with air pumping rate 1 l/m |
50-70 c |
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Dimensions and weight of analyzer |
460x210x110 mm, 7.5 kg |
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Dimensions and weight of PYRO-915 (without power supply
unit ) |
350x300x150 mm, 5 kg |
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Power requirements for analyzer |
220 Vac, 15 W |
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Power requirements for PYRO-915 |
220 Vac, 300 W |
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· RA-915+ mercury analyzer
· PYRO-915 unit
· A PC with OS Windows-95 or higher version with the dedicated software
· standard sample set
· installation and commissioning
View/Download Application notes in PDF format:
All LUMEX equipment is covered by 12-months warranty
Upon request installation and commissioning of LUMEX instruments
can be carried out on Customer's site by our service engineers.
Consultations and initial training of attendance personnel with
due account of Customer's specific needs are performed. Spare
parts are delivered and repair is made upon Customer's request
(free within the warranty period).
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