Metrohm Vision Manual User Manual
Page 25
▪▪▪▪▪▪▪
23
On the other hand, on most process instruments the reference and the sample fibers are separate.
The reference fiber (channel) is identical on all instruments. However, the sample fiber (channel) is
most often much longer than the reference fiber; its length depends on the actual instrument
configuration. The qualitative or quantitative models created on such an instrument depend on the
difference of the lengths of reference and sample channels. These models work well on the
instrument they have been created for, but method transfer is often complicated.
The use of External Reference allows the user to get rid of the fiber characteristics from the acquired
spectra, and consequently from the analytical methods.
The recommended way of using the External Reference feature is as follows:
•
Acquire a spectrum of the empty sample channel (no sample present, e.g., empty process
line).
•
Save the spectrum in a chosen product. This spectrum contains the fiber characteristics.
•
When ready to take real spectra, click on Acquire/Use External Reference.
•
Acquire and save spectra, and create a model.
When the model is used in Routine Analysis, define the External Reference in the Operations
Method. Make sure that the External Reference spectrum is identical to the one used in Data
Acquisition. Available methods will be displayed as follows: