16
How the unit works
Dispensing
modes
This instrument offers two (2) very different operation modes. The choice of the
mode will depend on internal laboratory procedures, as well as on the type of
intended analysis.
Fixed-weight mode
When preparing a sample for fusion, the laboratory protocols often call for a fixed
amount of sample, to be mixed with a fixed amount of flux. (That will in fact
always be the case when preparing for analysis in a liquid solution, e.g. for ICP.)
This instrument can be set to deliver accurate fixed amounts of flux. Every time
the user will activate the dispensing, the same weight will be dispensed in the
crucible.
Ratio mode
When preparing a sample for fusion with a view to analyze the results by XRF (X-
ray fluorescence), the analytical instrument will measure the concentration of the
elements present in the flux-and-sample mix.
So, of the sample has been dispensed and weighed first, the weight can be
recorded internally and then automatically multiplied by a ratio, to obtain the
same sample/flux ratio at every dispensing.
Example: with a sample/flux ratio set at 1/8
If the amount of sample is 1 g, then the amount of flux will be 8 g.
If the amount of sample is 1.
1
g, then the amount of flux will be 8.
8
g.
As long as the ratio is the same , the XRF spectrometer will not “see” any
difference in the concentration of the sample.
This gives a tremendous advantage, as this allows the operator to weigh the
sample quickly and fairly approximately, while the unit takes care of adjusting the
ratio perfectly.
