Wavelength Tech Forum: FTIR-NIR Spectroscopy

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 Jerry Sellors, Technology Manager for PerkinElmer, Inc., Richard A. Larsen, Scientific Applications Manager for Jasco, Inc., and Jim Yano, Vice President of Marketing for Aspectrics.

In which industries is the use of FT-IR/NIR most popular? Why?

Sellors: The FT-IR market is fragmented. Pharmaceuticals make up the largest segment at roughly 15 percent to 20 percent. Academia and government laboratories combined account for roughly 20 percent. Inorganic chemicals, including petrochemicals, make up about 15 percent, and biotechnology makes up about 10 percent. Other industries, e.g., semiconductors and independent testing labs, make up the rest of the market.

For NIR, the agriculture and food markets are the largest segment at roughly 30 percent to 40 percent, much larger than they are in FT-IR. After that, the market is split between pharmaceuticals, biotechnology, and inorganic chemicals, similar to FT-IR. Why: The agriculture and food industries use NIR because it requires a lower skill base to operate. These markets use the technology for more routine measurements like quality control. FT-IR is used for more analyses requiring very precise measurement and a more highly skilled operator.

Larsen: FT-IR, FT-NIR use is almost universal across all industries. There doesn’t seem to be much of a preference for dispersive infrared instruments anymore. FT spectrometers are much simpler mechanically, provide excellent signal-to-noise data in a minimal amount of time, and are quite affordable compared to the industry 20–30 years ago. Forensics labs, polymer and chemical manufacturers, and numerous other industries have found uses for FT-IR/NIR to assure the consistency of manufactured products as well as quality assurance of incoming materials.

Yano: Scanning-based systems like FT-IR and FT-NIR are well suited for the controlled environment of the petrochemical, chemical, and food and beverage research laboratories. These sensitive scanning spectrometers work well in the nonprocess environment where high resolution is required.

What are some of the advantages of using FT-IR?

Sellors: FT-IR is highly specific in its ability to identify molecular species. In general, it is simple to use and highly reproducible.

Larsen: Fellgett’s (multiplex) advantage - the accumulation of multiple scans to increase SNR; Jacquinot’s advantage - the use of a circular aperture vs. the rectangular aperture of a dispersive instrument; Connes advantage - the wavelength accuracy of FT instruments based on the wavelength of the HeNe laser used to track the interferometer movement. These advantages of FT-IR technology translate into advantages for the following applications:

• Opaque or cloudy samples

• Energy-limiting accessories such as diffuse reflectance or FT-IR microscopes

• High-resolution experiments (as high as 0.001 cm^-1 resolution)

• Trace analysis of raw materials or finished products

• Depth profiling and microscopic mapping of samples

• Kinetics reactions on the microsecond time-scale

• Quantitative analysis applications

• Analysis of chromatographic and thermogravimetric sample fractions

Yano: FT-IR systems are sophisticated instruments with moving mirrors and an internal laser capable of high resolution, making them ideal research instruments. Encoded Photometric Infrared (EP-IR), on the other hand, is a rugged technology well suited for the process monitoring industry.

How is FT-IR imaging being used in medical and pathological diagnostics?

Sellors: Many research institutions are using FT-IR imaging for spectroscopic diagnosis of tissue sections. The largest use of these images is in many types of cancer research, but it is also being used increasingly for a wide range of disease testing such as blood serum analytes and dental diseases.

Larsen: There have been some experiments examining tissue samples for differences in the various proteins. The biggest limitation, however, is the spatial resolution of infrared spectroscopy, limited to approximately 10 µm. The cost of imaging systems is also limiting the growth of imaging applications in clinical and medical diagnostics applications. Secondary structure estimation of proteins is a growing application that will see more use, but again, the sensitivity of infrared spectroscopy does have some limitations in this area as well as the strong interference of water in aqueous samples.

Yano: We have seen a real interest in using infrared spectrometers for biomarker research. One example is breath analysis. The idea is that patients would breathe into a sample accessory and the breath would be analyzed for components related to certain types of cancer. We feel that the small size and fast scan rate of Encoded Photometric Infrared (EP-IR) make it an ideal candidate for biomarker research. Because EP-IR can rapidly scan the spectral range, the technology is ideal for screening multiple biomarkers.

Do you anticipate further growth for FT-IR? In what applications?

Sellors: Yes. Growth is likely to occur in the biofuels market, where there has already been an increase in the use of biodiesel materials. There will also be growth in imaging applications, pathological diagnostics, environmental applications, and homeland security applications.

Larsen: The requirements for Process Analytical Technology (PAT) in pharmaceutical manufacturing are driving the use of FT-NIR instrumentation for on-line analysis of samples during production. As the instrumentation gets smaller and more compact, further application of FT-IR and FT-NIR will grow for these applications as well as other on-line analyses methods.

Yano: The real growth in infrared is occurring in the process monitoring market, not the research market. Unfortunately, FT-based systems are not well suited for the harsh process environment. We believe that the demand for infrared instrumentation in the process monitoring markets such as food/beverage, hydrocarbon processing, and PAT, as well as demand from the CleanTech markets, will fuel growth for a new process, rugged infrared technology - Encoded Photometric Infrared (EP-IR). Aspectrics EP-IR technology was designed to perform in the vibration prone process environment. Recent military specification certification confirms EP-IR to be a rugged infrared technology for the process environment.

Are there any other important trends in this area that you see emerging?

Sellors: First, the profile of the user is changing. The equipment is no longer being run just by scientists, but by operators with much less technical background. This presents a challenge in the instrument design process, because the instrument must be easy to use. The company I represent is committed to ensuring a high-quality, easy-to-use instrument that increases the pace and precision of scientists’ research. Also, the location of analysis is changing. For example, applications in the homeland security industry require a mobile instrument that can be used at locations outside of a laboratory. This requires miniaturization of the instrument so that it can be transportable.

Larsen: In the past, the interpretation of infrared spectra to obtain identification of the compound has limited the use of infrared spectroscopy to highly trained individuals. The sampling methods have also been somewhat limiting as a result of the requirements for infrared analysis. The ability to search obtained data against a growing amount of library databases provides positive identification of compounds without explicit interpretation of the infrared spectra. Simple, easy-to-use accessories have redefined the sampling capability of infrared instruments. As the cost of imaging systems decreases and the size of the instrumentation decreases, I believe we will see more application of FT-IR/NIR to other analysis applications. In addition, the development of application-specific instruments and software will provide additional opportunities for laboratories to incorporate FT-IR and FT-NIR instrumentation. Quantitative analysis applications continue to grow and develop without the requirement to provide complete interpretation of the spectra. All of these trends will provide the ability to incorporate additional infrared spectroscopy instruments into the analytical laboratory.

Yano: As a result of the growth in the process monitoring market, we anticipate a demand for simpler and lower cost-of-ownership instrumentation to drive future product developments. Like many other technologies, we see a demand to make infrared instrumentation as easy as running a PC. Consequently, Aspectrics EP-IR is designed to allow operators to embed calibrations so that the analyzer is capable of streaming real-time quantitative results, not spectra, anywhere in the world. It is important to recognize that many process technicians are not spectroscopists. As a result, there is a desire to stream real-time results and not spectra.