In applications such as pH determination, process analytics is securely in the driving seat. As yet unexploited potential, in contrast, is still slumbering in spectroscopy. A solution is promised by new data analysis methods as well as the integration of analysis equipment into control systems.
“PAT is here to stay!” If one believes this conclusion, voiced by the process analytics working group, PAT has finally arrived in production. This optimistic prognosis for the future of process analytics was given by the working group following this year’s International Forum Process Analytical Technology in January. The Forum, for which the sector came together in Baltimore, showed that the FDA had so far received almost 50 applications regarding the perennial NIR spectroscopy – with applications relating above all to identification, uniformity and blending.
Top Trends for Process Analytics: Tools Like Spectroscopy Take the Lead
Even a few years ago, a prognosis on the future of PAT would probably have been more cautious. In 2004, for example, the giant in the sector, BASF, used around 11 000 process analysis devices at its Ludwigshafen location for more than 50 measurement principles, yet the use of the devices was on the whole limited to classical methods. Around 4500 devices measured pH, redox and conductivity values. In second and third place were gas warning sensors (around 3500 devices) and photometers (around 1200 devices) .
Techniques such as spectroscopy played – despite their advantages of non-contact measurement, freedom from destructive sample-taking and high speed – a somewhat subordinate role. In retrospect, this is surprising in view of the important tasks tackled by spectroscopy, as at BASF: here, for example, the composition of syngas was monitored with the help of online IR-spectroscopy. In this case, the PAT experts from Ludwigshafen were successful in detecting reliably CO, CO2, H2S, CH4 and COS, although they occurred in very different concentrations. CO, for example, reached an average value of 44.9 percent, whereas COS reached only 62 ppm.
Suitable Analytical Methods Sought
Measurement tasks of this kind continue to be a great challenge for PAT specialists today. Modern analytical measurement technology produce real floods of data. To analyse these, chemometrics has mathematical and statistical methods at its disposal. Without these tools, the spectra in NIR spectroscopy cannot be evaluated at all.
In order to reduce the vast number of variables to a few components, principal component analysis (PCA) is often employed. One disadvantage of this analytical method, according to Prof. Dr. Rudolf Kessler, professor of chemistry at Reutlingen University and board member of the process analytics working group, is that it often offers only an inaccurate reflection of the physical chemical background. “It is therefore desirable to develop new methods for complex data analysis, methods which enable the integration of basic knowledge of the process into the chemometrical description,” Kessler urges .
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