Drying System T/IR
With the electrothermal evaporator ETV-4000 it is possible to evaporise besides solid samples also liquid or wet samples. This is most interesting especially when liquid standards have to be used. Doing this directly of course makes a part of the water- vapour to condense along its way through the transport tube. These water residues absorb a part of the analyte coming along what finally leads to wrong analysis results. By this reason such samples should be dried carefully after weighting in a way that there is no loss by boiling and that at the same time no liquid parts of the analyte get lost by diffusion through the graphite boat itself. This means that it is importent to have the boat to be heated from both sides just in the appropriate manner: not too fast and not too slow! A practical device for this procedure is the drying unit T/IR.
Function and Operation
The drying unit T/IR consists of a homogeniously heated and thermostated plate manufactured of aluminium. Its temperature is contolled to <100°C. At this heated plate the boats can be disposed, possibly even in complete magazines of graphite.
Above the heated plate there is a medium-frequency infrared-emitter with gold-reflectors. The radiator is adjustable in heigh and power and heats the disposed boats from their top side.
An integrated digital thermometer displays the actual temperature of the heated plate.
The liquid sample should be disposed into the boat just befor beginning to heat it. The basic idea is to heat in contrary direction to the diffusion of liquid sample material through the graphite. At the same time by carefully heating from above makes the water from the sample softly to evaporate without boiling effects and without losses of low-boiling elements from the analyte by overtemperature.
The temperature of the heated plate itself is stabilised to about 90°C+/-10°C. The power of the IR-radiator can be adjusted by a turning knob at the front panel. The heat emitting elements should be glowing at a slightly(!) red colour at a distance to the sample of about 15-20 cm.
For the reduction of contaminations coming from the laboratory environment - and also for a storage of samples and boats - the placement of the instrument inside a plexiglass-hood flushed by cleaned air is recommended (supplier: Spetec GmbH)
electrical supply: 230V/6A
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