588
R. W. Kessler and W. Kessler
23.7.2 Final Functionality Test of the PAT Spectroscopic
System for Long-Term Operation
As described before, the concept of robustness is the capacity of a model to remain
stable under small perturbations. The perturbations can be spectral in nature, chemical
outliers, temperature shifts due to uncontrolled reactions or any other uncontrolled
variables and data from different instruments where inter-instrument transferability
is limited [33, 43–45, 82, 83].
In summary, before installation, the following sources of perturbations should be
avoided and implemented into the PAT system:
• Reduced noise, especially baseline noise, for best signal-to-noise ratio.
• Selection of the optimum dynamic range of the measurement.
• Selecting the best possible reference.
• Working inside linearity and the highest precision of Lambert–Beer’s law, e.g.,
within the Twyman–Lothian curve.
• Minimum stray light of the optical setup.
• Optimized quality of the optical setup including beam guidance, cell positioning,
no instrumental wavelength variations.
The easiest way to check the system performance over time is to measure the
reference once as a reference and without any change also once as a “sample.” In
this case, a 100% transmission straight line should be observed. This 100% line
should be kept over a long time period [83]. With a suitable scaling, even small
differences at the low and high ends of the usable wavelength range as well as the
noise level can be judged. Running the system over a longer period, baseline drift,
lamp temperature drifts and all other possible perturbation can be quantified.
23.7.3 Conclusion
A key element for a successful implementation into industrial life is the trans- and
interdisciplinary collaboration of process managers, chemometric data analysts, electronics engineers, process specialists, and chemists with domain knowledge of, e.g.,
spectroscopy. It is important to bring them together in a business environment. But
prerequisites of the project are also management support and the conviction of the
staff that the project will indeed be a success. This means a “top-down” strategy of
the employers and “bottom-up” strategy of the employees and a sound knowledge
of the “champions” in the company.
R. W. Kessler and W. Kessler
23.7.2 Final Functionality Test of the PAT Spectroscopic
System for Long-Term Operation
As described before, the concept of robustness is the capacity of a model to remain
stable under small perturbations. The perturbations can be spectral in nature, chemical
outliers, temperature shifts due to uncontrolled reactions or any other uncontrolled
variables and data from different instruments where inter-instrument transferability
is limited [33, 43–45, 82, 83].
In summary, before installation, the following sources of perturbations should be
avoided and implemented into the PAT system:
• Reduced noise, especially baseline noise, for best signal-to-noise ratio.
• Selection of the optimum dynamic range of the measurement.
• Selecting the best possible reference.
• Working inside linearity and the highest precision of Lambert–Beer’s law, e.g.,
within the Twyman–Lothian curve.
• Minimum stray light of the optical setup.
• Optimized quality of the optical setup including beam guidance, cell positioning,
no instrumental wavelength variations.
The easiest way to check the system performance over time is to measure the
reference once as a reference and without any change also once as a “sample.” In
this case, a 100% transmission straight line should be observed. This 100% line
should be kept over a long time period [83]. With a suitable scaling, even small
differences at the low and high ends of the usable wavelength range as well as the
noise level can be judged. Running the system over a longer period, baseline drift,
lamp temperature drifts and all other possible perturbation can be quantified.
23.7.3 Conclusion
A key element for a successful implementation into industrial life is the trans- and
interdisciplinary collaboration of process managers, chemometric data analysts, electronics engineers, process specialists, and chemists with domain knowledge of, e.g.,
spectroscopy. It is important to bring them together in a business environment. But
prerequisites of the project are also management support and the conviction of the
staff that the project will indeed be a success. This means a “top-down” strategy of
the employers and “bottom-up” strategy of the employees and a sound knowledge
of the “champions” in the company.