Function and setup of the PlasmaQuant PQ 9000
PlasmaQuant PQ 9000 (Elite)
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Function and setup of the PlasmaQuant PQ 9000
3.1
Physical functional principle of ICP-OES
ICP Emission Spectrometry (ICP-OES) makes use of plasma with temperatures of up to
10 000 K. This high temperature is focused on a very small area of approx. 5 cm
3
. The
sample is introduced to this plasma in the form of aerosol (small droplets in a glass).
The droplets dry, melt, vaporize and atomize or ionize. During this process, the analysis
channel of the plasma through which the sample is flowing cools down to approx. 6 000
to 7 000 K.
Atoms and ions are excited to emit light at these high temperatures. The light is broken
down by the device optics into wavelengths ("colors") tube intensity is measured to indi-
cate concentrations. A detector is used to measure the intensity of the emission line and
its spectral environment. The net intensity of the measured signal is used as a measur-
and ("peak").
The inert gas argon is used as the operating gas. This gas flows inside a plasma torch
made up of three concentric pipes. The plasma gas (also called cooling gas) flows at a
rate of 10-18 L/min on the outside to cool the external torch pipe. The sample aerosol
is injected in the plasma in the inmost pipe, hence its name "injector". The sample aero-
sol is created shortly before with a nebulizer and a downstream spray chamber in which
larger droplets are separated.
The exhaust heat of the plasma is dissipated partly by the recirculating chiller and partly
by the exhaust unit.
3.2
Function and setup of the PlasmaQuant PQ 9000
Essentially the PlasmaQuant PQ 9000 consists of the following components
Components for plasma generation (HF generator, induction coil, torch)
Sample supply system with peristaltic pump, nebulizer and spray chamber
Optical system with transfer optics, spectral photometer and detector
Technologically, the difference between both models, PlasmaQuant PQ 9000 and Plas-
maQuant PQ 9000 Elite, is in their optics. The components for plasma generation and
the sample supply system are identical. For applications with severe spectral interfer-
ences (e.g. for rare earths, refractory metals) the higher resolving power of the Plasma-
Quant PQ 9000 Elite benefits high detectability, precision and ease of use. Despite the
lower spectral resolution, the PlasmaQuant PQ 9000 offers excellent detection limits in
standard applications.
The sample introduction system is freely accessible in the sampling compartment. The
torch and the induction coil, however, are located in the shielded plasma compartment
to protect the user from the high-frequency radiation and the UV radiation from the
plasma. The spatial separation between sample supply and plasma also prevents the
heat radiation from the plasma being transferred without obstruction to the spray
chamber and causing a drift there.
Sampling compartment
and plasma compartment