FT-IR/NIR

December 7, 2010

Fourier-transform infrared (FT-IR) and near-infrared (NIR) spectroscopy are used for many applications in organic and inorganic chemistry, including QA/QC; forensic, food and beverage, pharmaceutical, medical, and semiconductor analysis; and other materials characterization. Joining us for this discussion are Jeffery Hirsch of Thermo Fisher Scientific and Dr. Brian Curtiss of ASD, Inc.

Fourier-transform infrared (FT-IR) and near-infrared (NIR) spectroscopy are used for many applications in organic and inorganic chemistry, including QA/QC; forensic, food and beverage, pharmaceutical, medical, and semiconductor analysis; and other materials characterization. Joining us for this discussion are Jeffery Hirsch of Thermo Fisher Scientific; Dr. Brian Curtiss of ASD, Inc.; and D.L. Wetzel of Kansas State University.

How would you describe the state of FT-IR/NIR technology right now? Is it growing into more application areas? Contracting?

Hirsch: FT-NIR continues to prove its use as an extremely practical technique, providing spectroscopic information on a wide range of materials from field to lab to line. The technology continues to evolve to shorten the distance between sample and answer

Curtiss: We have seen a growth in the demand for NIR spectroscopy instrumentation. The market in general has survived well through the recession. The growth of the research segment appears largely to be due to stimulus funding put into place both in the United States and China. Recently, advances in NIR spectroscopy have spurred interest in other industrial applications such as mining and pulp and paper production.

Wetzel: Because of the modern spectroscopic technologies the applications are expanding into other disciplines. The term spectroscopy without spectroscopists was initially coined in reference to near-IR because once a calibration was established, technicians with little or no background did the analyses. Now in mid-IR hazmat first responders, police, Coast Guard, and firefighters, since the anthrax alert, can use a rugged FT-IR spectrometer with diamond ATR and use the embedded spectral library to check for the presence of a hazardous or illegal material.

What are the most important recent developments in FT-IR/NIR spectroscopy?

Hirsch: One of the most significant developments in this area has been the success of handheld NIR instruments for point-of-use analysis. This has already played a critical role in the security, authentication, and raw material ID markets. From the process side, the introduction of software that is readily compatible with process systems, such as those using an OPC server, has brought the value of FT-NIR spectroscopy directly to the process line for true information feedback.

Curtiss: NIR spectroscopy instrumentation has advanced to the level that it provides industrial companies more complete data — and actionable information — on materials in process. It’s not enough to provide customers with the means to collect spectroscopic data, but you must provide the software tools and calibrations necessary to convert that data into actionable information.

Not only is NIR getting better at performing measurements in the laboratory, but the instrumentation necessary for near- or in-process real-time measurements is now available.

Many companies don’t want to wait for the analysis results of samples sent off to a lab. The newer types of NIR spectroscopy solutions are well suited to quickly measure relevant constituents either near-line or in-process.

With growing interest in improving end-to-end processes for greater budget savings or to improve process efficiencies, the need for these types of full analysis solutions where the materials are, continues to increase.

Wetzel: The most important high-end developments in mid-IR include the commercial availability of infrared microspectrometers, their use with synchrotron illumination, and imaging instruments that use focal plane array detection.

For utiliarian emphasis with condensed phase work compact modulators with 4 cm-1resolution provide portability to take the FT-IR to the industrial site.

Sampling techniques allow an interferometer to serve as an attachment to a research grade instrument as developed by Reffner. Also, the combination of diamond ATR with a modulator smaller than a cigar box designed by Reffner at SensIR and subsequently copied is the reason the identification of unknown solid or liquid substances can be carried out by trained operations in the absence of educated spectroscopists.

Has portable FT-IR/NIR instrumentation advanced to the point where it is comparable to benchtop instrumentation, or is there still work to do in this area?

Hirsch: Handhelds have proven ready-to-use for applications in the homeland security market as well as raw material ID where size and weight requirements dominate. Process integration and sampling of highly heterogeneous and other challenging materials are two facets of FT-NIR analytics where benchtop instrumentation still has the edge.

Wetzel:Near-IR instrumentation has diversified to include commercial alternatives to the original filter or grating monochromator instruments. FT-NIR and no moving part acousto-optic tunable filters (Kemeny, Wetzel), liquid crystal tunable filters (Treado), and compact diode array polychromator spectrographs (Stark) offer choices depending on the application. Wavelength precision is sufficient to allow spectral subtraction. Near-IR imaging that initially targeted the pharmaceutical industry is starting to mature with two pushbroom array instruments available. Associated software enables pixel i.d. and subsequent pixel counting provides quantitative analysis of solid mixtures of mixtures from a locally generated library of component spectra.

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

Hirsch: FT-NIR is poised to continue its strong presence in the pharmaceutical and food markets. We are seeing cutting edge applications like stem cell monitoring and cell culture analysis in areas like biotechnology and biochemistry that represent several high growth areas for FT-NIR in the coming years.

Curtiss: We’re seeing a huge interest in better understanding of global climate, particularly the interaction between the earth’s surface and atmosphere as it relates to atmospheric CO2. A specific project with which my company is involved is finding ways to maximize soil carbon storage. Organic carbon plays a major role in how well a cultivated field holds moisture, provides nutrients, and remains productive, so there’s some crossover interest into the agriculture industry. The ideal goal being of course, to improve crop productivity while helping to offset greenhouse gas emissions from other sources.

As an example of how the technology has progressed in the pulp industry, mill operators are now using a bench-top instrument, to perform simultaneous Kappa number and brightness measurements in less than 4 min, with minimal preparation time and without chemicals.

Other calibration models are actively in development for clay determination at gold and copper mines. In both industries, analysis can be performed much faster than in traditional lab operations by bringing the instrument to the material. The higher quality of information generated by the models may also help to lower costs by reducing the use of expensive chemicals or laboratory assays.

Wetzel:In both mid and near-IR, imaging of specimens will be used in research applications to locate chemical points of interest that will be subjected to serious spectroscopic interpretation. This will increase as more forensic, materials, pathology, and health practitioners discover its value of localized chemical analysis.

What do you see as the next step in FT-IR and NIR technology and instrumentation?

Hirsch: Few analytical techniques provide the wealth of information across the range of applications that vibrational spectroscopy does. That said, I think we will start to see smaller, more robust instrumentation on the laboratory side and more approachable, user-friendly software that allows anyone to get answers from an analyzer.

Curtiss: While there are some industries that typically have in-house capabilities to fully develop a spectroscopic analytical solution, there are others that don’t. Companies that can provide the complete solution — from instrumentations, software, installation, and support to calibrations… and wherever they are needed — will be the ones that really thrive.

Wetzel:The next step is the use of tunable lasers to scan the spectrum or provide random wavelength access for multivariate analyses. Reducing the cost will be a challenge. Also, converting multiwavelength methods to dedicated single use portable cost inspection tools to develop an almost mass market as found with the calculator syndrome or the more recent cell phone explosion.

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