Technology Forum: FT-IR/NIR

With the popularity of FT-IR/NIR continuing to grow, it is not surprising that Spectroscopy is dedicating a second issue of “The Wavelength” this year to these invaluable techniques. Used in almost all application areas from pharmaceutical to biomedical to homeland security, these techniques are true workhorses in the world of materials analysis.

This month's Technology Forum looks at the topic of FT-IR/NIR and the trends and issues surrounding it. Joining us for this discussion are Robert Mattes, FOSS NIRSystems, Inc.; Debbie Peru, Colgate Palmolive; and Dr. Richard A. Larsen, JASCO.

How have improvements in software made the FT-IR/NIR field better?

Mattes: NIR chemometric software has made it possible to analyze samples containing complex matrices of chemical components without separatory methods or sample preparation. Partial least squares methods coupled with fast personal computers have made real time process predictions possible in-line.

Peru: Putting computer speed aside, the development of scatter correction methods such as SNV, extended SNV, and MSC have provided much better results in the analysis of NIR for solids and some liquid samples. The application of advanced methods such as 2-D correlation provides spectral separation and speciation, and MCR helps with reaction interpretation. Even some of the smart software can help novices develop quantitative methods faster, although this can be dangerous since most of the smart software tend to overfit the data.

Larsen: The availability of various analysis packages (e.g., PCR, PLS, PCA) has allowed greater capabilities for the interpretation of complex spectra, increasing the utility of infrared spectra for various analyses. As well, the development of “packaged” analytical methods utilizing infrared spectroscopy has provided a wider range of capabilities for the user of infrared instruments.

What do you see in the future for quality control in FT-IR/NIR?

Mattes: The application of NIR for process monitoring and control has continued to grow over the last decade. Process analytical technology (PAT) has had erratic starts in the pharmaceutical industry due to the regulatory anxiety of GMP environments. However, many industries, including petroleum and polymer as well as pharmaceutical, have implemented NIR at-line, on-line, and in-line for quality monitoring and closed loop feed back control. Using statistical process control techniques processes can be monitored and problems can be detected and corrected before discrepant material is produced.

Peru: More and more quality control testing methods are being developed with FT-IR/ IR because of the speed and elimination of sample pretreatment.

Larsen: As the instruments continue to decrease in cost, while additional, more “universal” accessories are developed (e.g., fiber optic probes, integrating spheres, micro-ATR accessories), the use of FT-IR and FT-NIR for QA/QC operations will certainly continue to increase.

What are some applications in which you anticipate growth in the use of FT-IR/NIR? Why?

Mattes: I anticipate growth for process applications. In the chemical, biotech, pharmaceutical, etc, industries the application of NIR to their processes can help them optimize extremely complex process parameters. NIR can make predictions on multiple parameters from each spectrum after the initial calibration work has been done.

Larsen: The use of infrared microscopy continues to increase as the requirement for more “perfection” in products is desired. FT-IR and FT-NIR microscopy have become an essential tool for defect analysis of consumer products. The use of infrared imaging for analysis of samples is also increasing due to the decrease in cost for these systems as well as the increased capabilities for these systems and the continued development of user-friendly software systems.

What has been the biggest advancement in FT-IR/NIR in the last few years?

Mattes: I would say the improvement of signal-to-noise in the instruments. High resolution is not useful in the NIR region because the bands are broad (about 10 nm or more) and in the final analysis it is signal-to-noise that determines reproducibility and quantitative predictive limit of detection. Also, in a global economy instrument matching and model transferability are important, because many companies develop calibration models at one location and have NIR instruments around the world predicting with essentially the same equation.

Peru: Smaller footprint and hand held devices for use by non-chemists.

What is the role of FT-IR/NIR in homeland security? How has instrument portability affected this area?

Mattes: There might be areas in homeland security where NIR could be utilized. However, in many cases there are other analytical techniques available that can do the job better.

Peru: While there has been much press regarding the use of FT-IR/NIR for homeland security purposes, many of the applications tend to be detection at the ppm or low % levels. For this level of accuracy, the signal to noise needs to be much better than that currently afforded by hand-held devices. Currently, the use of hand-held devices is mostly being used for pure material testing at the high percent levels.

Larsen: Infrared spectroscopy can provide rapid identification for most chemical compounds. The instrumentation is fairly inexpensive, compared to other analytical methods, and relatively easy to use. As well, the development of portable, dedicated instruments and continued release of search libraries for rapid identification of “unknown” or potentially dangerous compounds offers a unique capability for homeland security providers. While no instrumental technique can provide a “universal” capability for homeland security operations, infrared spectroscopy is very valuable as a screening method, providing a rapid go/no-go decision with respect to requiring more detailed analysis of possibly dangerous chemicals.

What do you think?

Click here to participate in our "Question of the Month" survey on FT-IR/NIR.