Function and setup of the PlasmaQuant PQ 9000
26
Edition 05/2014
PlasmaQuant PQ 9000
Figure 3
Sampling compartment and plasma compartment in the PlasmaQuant PQ 9000
HF generator
The PlasmaQuant PQ 9000 uses a free-running 40 MHz HF generator (High-Frequency
Generator). The HF generator transfers power ranging from 700 to 1700 W into the plasma
assisted by the high-performance coil. Fully automated matching of the power output to the
actual sampling loads in the plasma enables ultimate consistency of plasma conditions. This
means the plasma is very robust and is able to master even challenging sample matrices such
as organic solutions or salt loads. The HF generator is located immediately behind the plasma
compartment and is shielded separately because of the high intensity of high frequencies.
The power for maintaining the plasma is transferred by means of an induction coil with four
windings in the torch in the plasma compartment. The induction coil is water-cooled.
During the initial plasma ignition period, a high voltage spark is passed from the conducting
spring located in the vicinity of the induction coil through the high-frequency field in the torch.
Pump, nebulizer and spray chamber
A hose pump conveys the measurement solution at the same rate to the nebulizer. The
rotational speed of the pump and the diameter of the pump tubing used determine the amount
of sample delivered. By using the pump, sample introduction into the nebulizer and thus also
the sensitivity of the measurement signal is independent of the viscosity of the measurement
solution.
The aerosol of the measurement solution required for atomization/ionization in the plasma is
generated by a pneumatic concentric nebulizer. An argon flow is directed past the sample
nozzle of the nebulizer as nebulizer gas. The gas flow continuously tears the surface of the
liquid at the nozzle and produces small sample droplets. The sample aerosol that is formed is
transported with the nebulizer gas through the spray chamber to the plasma. On the way
through the spray chamber, large droplets in the spray chamber are separated by the
centrifugal force and flow out via the waste outlet. A cyclone chamber is used as the spray
chamber.
