The Kittiwake ANALEX range of instrumentation is used in laboratories and in the field worldwide
Info Centre >> Analex PQ Instruments FAQ >> How does the PQ Index relate to ppm of Iron using methods such as ICP?
Users of spectroscopic methods (SOA) report their data in parts per million. However, spectroscopic methods are often inaccurate in absolute terms because of the insensitivity of these techniques to large particles and the problem of sample inhomogeneity. SOA is typically most efficient with sample particle sizes <5 micron in size. The spectroscopic analysis will also vary according to the shape of the particles concerned.
Many commercial laboratories are now using both SOA and PQ side by side and the analytical results from the two techniques are often interpreted in the following manner. If the "PQ index" is less than the "ppm Fe" analysis by SOA, it is likely that all debris is <5 microns in size (this is typical for corrosive wear particles). If the "PQ Index" and the "Fe ppm" by SOA are similar or especially if the PQ Index is higher then there will be large particles in the sample. The sample is then examined by microscope to check for the presence of large particles.