Infrared spectrophotometry illuminates IFPAC

Around the Loop columnist Terrence K. McMahon attended the recent IFPAC meeting in Washington and reports that in 2004, 12–15,000 NDIR units were shipped worldwide for use in process monitoring and control.

By Terrence K. McMahon

THE IMPORTANCE OF PROCESS analytical instrumentation to the missions of multiple federal government agencies was likely the key motivating factor attracting more than 500 conferees to the 19th International Forum on Process Analytical Chemistry (IFPAC) in Washington, D.C. (Jan. 10–13).

The Food and Drug Administration’s (FDA’s) Process and Analytical Technology (PAT) Initiative is the principal driver but by no means the only one. The defense establishment, the Department of Homeland Security, the national laboratories, the EPA, the National Institute of Standards and Technology and others were represented among the conferees and technical presentations. The largest group of conferees, just under 30%, represented the pharmaceutical/biotech industry (producers, FDA regulators, directly-related support firms and research consortia. About 20% of the 200-plus technical papers had “PAT” in their titles and many others dealt with the substance of this Initiative.

Making choices between simultaneous technical sessions is often difficult. Co-chairs Jerry Clemons and Ali Afnan assembled a formidable array of cutting-edge papers. Plenary speakers represented the FDA’s Center for Drug Evaluation and Research, Watson Pharmaceuticals, DuPont, Transducer Technology Inc., Xcellerex and ExxonMobil R & E. My partner, Steve Walton (PAI Partners), closed the plenary detailing the $26 billion or more outlook for the Process Analyzer Enterprise (2004–08) based on the results of a recent study.

I can’t begin to cover all the important matters discussed in the technical sessions and evening symposia. However, three papers on infrared spectrophotometry in particular caught my attention.
Bill Worthington of ABB Process Analytics reviewed the almost 70-year history of Non-Dispersive Infrared (NDIR) technology. This technology was born in the research labs of I.G. Farbenindustrie in the latter half of the 1930s, primarily through the efforts of Dr. Karl Luft and his associate Dr. Erwin Lehrer.

This research team also produced the paramagnetic oxygen analyzer a few years later. With over 300,000 units installed worldwide, NDIR is believed to be the most widely used continuous gas analyzer. By 1945, about 400 were working in the German chemical industry. In 2004, 12–15,000 NDIR units were shipped worldwide for use in process monitoring and control, based on PAI data. The NDIR analyzer has proven to be rugged and reliable over decades of use. Although enhanced continuously, particularly in the last 15–20 years, Luft and Lehrer would have no trouble recognizing their handiwork.

Tom Hagler of Aspectrics described a chemometrics-based analytical technology, Encoded Photometric Iinfrared (EPIR ) that combines the reliability of NDIR with the specificity of Fourier Transform Infrared Spectroscopy (FTIR). Through the use of proven rotary-encoder technology instead of a Michelson Interferometer, the instrument is much less sensitive to vibration, permitting its installation under industrial conditions. Because the analytical method, once developed, can be recorded and reproduced in a standardized, documented format, regulated applications in pharmaceuticals and environmental monitoring are among the targeted markets.

The last paper presented at the end of a conference is inevitably conflicted by travel plans and other last-minute emergencies. Ralf Marbach’s paper, “New Method for Multivariate Calibration,” should be still another reminder that “It ain’t over till it’s over.” VTT Electronics is an important player in process control R&D, having developed instrument technologies for ABB, Metso Automation and others. In the recent past, many Near Infrared Spectroscopy (NIR) instruments had a hook on the cabinet where the chain could be attached guaranteeing that a PhD analytical chemist was never far from the application.  Now, with Internet access, you only need to lock the chemist in an office to ensure the application. This is undoubtedly something of an overstatement, but the cost of model development and model maintenance has restrained NIR deployment as a process control tool.

  • The method described is applicable when the response spectrum is known (typically the case with process control) and has two primary advantages:
  • The cost of calibration is dramatically reduced because the need for reference values is virtually eliminated.

The specificity of response can be proven because calibration becomes transparent and controlled by the user (Science-based).

These are just three of more than 200 papers but offer a glimpse of the overall program.

  About the Author
Terrence K. McMahon of McMahon Technology Associates is the "Around the Loop" columnist for CONTROL magazine and He can be reached at