Frequently Asked Questions
What is NIR Spectroscopy?
Spectroscopy is defined as the study of the interaction between matter and electromagnetic radiation. It originated from visible light being dispersed through a prism according to wavelength. Evolution of spectroscopy as a concept expanded to include any interaction with radiative energy as a function of wavelength or frequency.
Most spectroscopic data are represented in the electromagnetic spectrum, although matter waves and acoustic waves can also be considered forms of radiative energy. Near-Infrared (NIR) Spectroscopy uses the region from 780 nm to 2500 nm in the electromagnetic spectrum and is based on molecular overtones and combination vibrations, creating a “fingerprint” of the sample. It is typically used for measurement of organic functional groups, such as O-H, N-H, and C=O.
NIR spectra can be collected using either transmission (light passes through the sample before collection by the detector and in most cases a liquid) or reflectance (light reflects off the sample and is collected by the detector).
Most NIR spectrometers consist of a light source, a detector, and a dispersive element (usually a diffraction grating) to allow the collection of light intensity at different wavelengths over time. One different type of instrument is a FT (Fourier Transform) -NIR spectrometer, which can simultaneously collect data over a spectral range.
NIR spectra typically show very broad peaks in the molecular overtone and combination bands of samples, making the spectra complex and difficult to interpret because features cannot be visually attributed to changes in specific molecules and compounds. Because of this, multivariate calibration techniques are often necessary to extract the desired information. This process is known as chemometrics and uses algorithms such as Principle Component Analysis (PCA) and Partial Least Squares (PLS) to use NIR spectra for both qualitative and quantitative analysis of the desired constituent of measurement.
What is the History of NIR Spectroscopy and How Have Recent Technological Advances Impacted The Animal Food Industry?
NIR spectroscopy has a long history dating back to the discovery of the first non-visible part of the electromagnetic spectrum by Sir William Frederick Herschel in 1800.
Herschel was testing different filters to pass sunlight through and noticed that filters of different colors generated varying amounts of heat. Further experiments entailed passing light through a prism to measure the different colors of light and in the process, Herschel took a measurement just beyond the red end of the visible spectrum. He detected a temperature one degree higher than that of red light and concluded that there was an invisible form of light beyond the visible spectrum.
At the time, Herschel referred to this region as “calorific rays” and it was later renamed “infrared”. Until the 1950s, the use of NIR spectroscopy as an analytical technique was dormant and it took a backseat to other analytical methods.
Mid-IR spectroscopy gained acceptance in the 1900s after the work of William Coblentz, who was the first researcher to obtain absorbance spectra of pure substances and verify their usefulness for the identification of organic functional groups.
NIR spectroscopy was neglected for many years because spectroscopists could not find any attractive information in the NIR region which was occupied by broad, super-imposed, and weak absorption bands. The work of Karl Norris at the USDA Agricultural Research Center pioneered the use of NIR spectroscopy as a modern analytical technique.
Norris built his own spectrometer using tilting filters and figured out that by using a computer with the spectral data as the independent variable, predicting the composition of an agricultural material was possible by calibrating the instrument with the laboratory determined composition as the dependent variable.
A groundbreaking paper published in 1965 by Norris paved the way for the adoption of a two wavelength model which could abandon Beer’s Law as a prerequisite for quantitative analysis. The highly scattered transmission of NIR light prevents Beer’s Law from being an effective equation for analysis.
The same paper also pioneered the use of diffuse reflectance as a non-destructive technique in the NIR region, allowing for direct measurement of samples with minimal preparation and without any pre-treatment. Ultimately in the 1970s, Norris developed the first commercial NIR analyzers for measuring protein in wheat and moisture in flour.
After the door was opened, the 1980s saw rapid advancement in the use of NIR spectroscopy as an analytical technique. Developments in instrument improvement, data treatment and processing, and the use of chemometrics for calibration models (largely dependent on advancements in computers) paved the way for widespread use of NIR spectroscopy in numerous industries.
Agriculture, Food & Beverage, Pharmaceuticals, Chemical, Petrochemical, and Polymers are just some of the industries where NIR spectroscopy emerged as an important analytical technique. The advantages of being fast, non-destructive, and non-invasive with strong light penetration and requiring minimal sample preparation have made NIR spectroscopy the analytical technique of choice for many applications. It is especially well suited for measuring small amounts of water and C-H bonds. After the initial boom in the 1980s and 1990s in the development of NIR spectroscopy, the technique was prominent but primarily used for benchtop and laboratory measurements.
Technological advances in hardware and software have helped move the focus on NIR spectroscopy from use as an offline analytical tool to an inline method that can be used for process control.
The Process Analytical Technology (PAT) initiative by the FDA created the framework for designing systems that can be used analyzing and controlling an entire manufacturing process. While formal implementation of this initiative has been limited outside of the pharmaceutical industry, the principles of PAT and benefits of real-time analysis are recognized. They have long been used in the petrochemical and chemical industries and have been implemented at many leading human and animal food manufacturers.
Some of the advancements that have helped advance the use of NIR spectroscopy as a real-time analytical tool include improved fiber optics and probes, multiplexed instruments, pre-built calibrations, instrument portability, and web-based platforms that support database management, trend and quality control analysis, and real-time virtual instrument and software maintenance and support.
The sections on this website provide a comprehensive review and examination of how NIR spectroscopy is used in the animal food industry.
What is the Difference Between Dispersive NIR and FT-NIR Spectrometers?
FT-NIR (Fourier Transform-NIR) is a technique used to simultaneously collect high resolution spectral data over the entire range of interest. There are significant advantages to this method over a dispersive spectrometer, which measures intensity over a very narrow range of wavelengths over time. This technique requires repeated measurements to obtain absorption spectra over the full range of interest.
FT-NIR spectrometers use a light beam containing multiple frequencies which is modified very quickly in a short period of time. This occurs by shining the light into a Michelson interferometer, a configuration of two mirrors. One mirror is fixed and the other moves to transmit and block different wavelengths of light. The raw data is the light absorption for each mirror position and processing is required to change the raw data into the desired spectrum showing the light absorption at each wavelength. The processing is known as a Fourier Transform and it converts displacement of the mirror (measured in cm and called an interferogram) into the inverse domain and resulting absorbance spectrum (wavenumber in cm-1).
FT-NIR spectrometers collect spectra in wavenumber (an inverse measure of distance/frequency) as opposed to dispersive NIR spectrometers collecting spectra in wavelength (a measurement of distance).
There are numerous advantages to using FT-NIR spectrometers over dispersive instruments. Both resolution and signal-to-noise ratio (SNR) tend to be higher for FT-NIR instruments. Higher SNR is the result of simultaneous wavelength collection as well as higher throughput. Wavelength accuracy is higher as well because wavelength is calibrated in FT-NIR instruments by passing a laser beam of known wavelength through the interferometer.
Wavelength calibration in dispersive instruments is dependent on the mechanical movement of diffraction gratings and this can lead to inaccuracy. Imperfections in diffraction gratings and accidental reflections can also lead to stray light in dispersive instruments, which is the radiation of one wavelength appearing in another wavelength in the spectrum. Because the wavelength is determined by the modulation frequency of the interferometer in FT-NIR spectrometers, there is no direct equivalent to the stray light that can be found in dispersive instruments.
The primary advantage of FT-NIR spectrometers is that instruments are inherently reproducible, which eliminates the need for method transfer of calibration models needed to analyze the spectra. The process of collecting spectral data and correlating reference values of the parameter of interest to the spectra using chemometrics can be time-consuming and reference tests can be expensive. When a calibration model is created using one dispersive spectrometer, it may not work on another spectrometer of the same type because of differences in the dispersive element.
One good example of this is AOTF spectrometers, which use a crystal modulated at different frequencies to disperse light into different wavelengths. Such instruments can never be reproduced due to the inability to duplicate crystals.
Calibration models can be transferred from one instrument to another using mathematical algorithms and software standardization. This process is known as method transfer. Method transfer can be difficult, time-consuming, error-inducing, and sometimes may not work at all depending on the type of spectrometer, especially when transferring to multiple instruments.
FT-NIR spectrometers require no method transfer between instruments, even when using calibration models made by a different vendor as long as the original instrument is also an FT-NIR spectrometer. This results in saving of time and resources, especially when deploying multiple instruments in a production environment.
What are the Advantages of Using NIR Spectroscopy Over Traditional Testing Methods and Other Spectroscopic Methods?
NIR spectrometers offer a fast, non-invasive, and cost-effective method for testing parameters of interest in numerous industries. There is little if any sample preparation required and no sample destruction. No chemicals or solvents are required for use.
While NIR spectroscopy requires the creation of calibration models using chemometrics to correlate spectra to reference values, once these models are constructed the benefits are enormous. Multiple parameters can be measured with a single scan after models are created.
Reference testing in the food and beverage industries often consists of expensive and time-consuming tests like HPLC and wet chemistry tests. These tests require skilled technicians and if not performed on-site, the results can take a week or longer to obtain. Performing such tests in a real-time process setting is often impractical if not impossible.
Advances in the technology of NIR spectrometers and the Process Analytical Technology (PAT) initiative have led to the implementation of NIR spectroscopy as a real-time process control tool.
Various spectroscopic methods exist but NIR spectroscopy has proven to be the most suitable technology in many industries for measuring parameters of interest in both laboratory and process settings.
NIR offers the advantages of little to no sample preparation, deep light penetration into the sample, and no sample destruction. Minimal or no sample preparation reduces operator error and eliminates the need for the use of toxic chemicals and solvents.
Deep light penetration is especially advantageous for measuring natural products when samples are often not homogenous. Some methods are not suited to measure parameters of certain organic molecules as well.
NIR spectroscopy is very well-suited for qualitative and quantitative analysis of organic compounds. Water is highly absorbed in the near-infrared spectral range, which makes NIR spectroscopy able to accurately measure even small changes in moisture.
How is NIR Spectroscopy Used in the Feed & Forage and Pet Food Industries?
NIR spectroscopy is used in numerous verticals in the feed & forage and pet food industries for testing of raw materials, intermediates, and finished products. Depending on the type of instrument, it can be used as a portable handheld mobile tool, a laboratory instrument, or a process control tool to optimize the manufacturing process and reduce waste.
Variation of natural products presents an inherent quality control challenge in not only feed & forage, but across the entire agricultural industry. NIR spectroscopy can be used for initial raw material identification and quantification of parameters of interest. Such information is immensely useful for both buyers and sellers of feed & forage products as well for scientists who use feed formation for nutritional optimization of final products.
Composition analysis requires the construction of calibration models to measure specific concentrations of parameters. Fat, protein, moisture, and carbohydrates are examples of macronutrient organic parameters that have been measured in feed & forage products. Fiber and energy components are crucial in compound animal feed final products and these can be determined using NIR spectroscopy. Even salt concentration can be determined in some cases even though it is not an organic molecule. Salt has an indirect effect on water molecules in a sample.
An indirect correlation is acceptable when constructing chemometric models for use by NIR spectroscopy, but such models must be carefully analyzed to ensure that the analysis is legitimate. Color analysis is another example of an indirect correlation which has successfully been measured using NIR spectroscopy.
After raw material content analysis, NIR spectroscopy can be used at various points throughout the manufacturing process. Laboratory instruments can be placed at-line next to different points in the manufacturing process. While lab instruments give a big improvement over traditional testing methods, the real benefits come from using NIR spectroscopy as a real-time process and formulation control tool.
Fraud and adulteration are tremendous problems in the feed and forage industry. NIR spectroscopy has been used as a tool to identify and monitor adulteration in products. Adulteration can constitute many different forms and methods. While perhaps unintentional, improper representation of nutritional content in both raw materials and final products is a form of adulteration.
In the case of agricultural products, variation in the same batch of materials can cause this type of adulteration to occur. Misidentification of a product is another common form of adulteration. Adding cheaper ingredients or dilution is another method of adulteration.
In some cases, this can be dangerous and present a health hazard, such as adding melamine to products containing protein. Melamine mimics protein in standard wet chemistry tests and in this case, NIR spectroscopy not only presents a faster and cheaper method for adulteration identification, it presents a solution when standard testing will not work.
A high- profile incident of this nature occurred in China with the adulteration of dog food with melamine. If an adulterant is identified in a product using NIR spectroscopy, the sample can be sent off for further testing. Large-scale testing is often impractical using standard methods and using NIR spectroscopy can be a powerful screening tool for adulterant identification.
The use of NIR spectroscopy as a real-time process control tool has become more prevalent as advances in technology have moved the focus of new instruments from the laboratory to the process.
Process Analytical Technology (PAT) is a framework for innovative process manufacturing and quality assurance. Critical points and parameters during manufacturing of a product are defined and the process is designed in a way that such points and parameters can be measured using analytical tools and instruments for real-time process feedback and control. Such instruments must be able to measure on-line and in a non-invasive manner. Many vendors have developed instruments that are able to measure multiple points in a process with a single instrument, usually using optical fibers and probes.
PAT has become an important part of pharmaceutical as well as chemical manufacturing and is beginning to acquire a hold in the feed & forage industry. In the case of pet food, one of the largest and most prominent pet food companies has successfully adapted NIR spectroscopy for quality assurance. The project has been so successful that the technology has been shared with competitors in the interest of creating safer products for the entire industry, ultimately benefitting all manufacturers, customers, and the pets themselves.
Real-time feedback using NIR spectroscopy can optimize the use of materials as well as reduce or eliminate the production of material that does not meet specifications.
Spectroscopy is defined as the study of the interaction between matter and electromagnetic radiation. It originated from visible light being dispersed through a prism according to wavelength. Evolution of spectroscopy as a concept expanded to include any interaction with radiative energy as a function of wavelength or frequency.1
Most spectroscopic data are represented in the electromagnetic spectrum, although matter waves and acoustic waves can also be considered forms of radiative energy. Near-Infrared (NIR) Spectroscopy uses the region from 780 nm to 2500 nm in the electromagnetic spectrum and is based on molecular overtones and combination vibrations, creating a “fingerprint” of the sample. It is typically used for measurement of organic functional groups, such as O-H, N-H, and C=O.
NIR spectra can be collected using either transmission (light passes through the sample before collection by the detector and in most cases a liquid) or reflectance (light reflects off the sample and is collected by the detector).
Most NIR spectrometers consist of a light source, a detector, and a dispersive element (usually a diffraction grating) to allow the collection of light intensity at different wavelengths over time. One different type of instrument is a FT (Fourier Transform) -NIR spectrometer, which can simultaneously collect data over a spectral range.
NIR spectra typically show very broad peaks in the molecular overtone and combination bands of samples, making the spectra complex and difficult to interpret because features cannot be visually attributed to changes in specific molecules and compounds. Because of this, multivariate calibration techniques are often necessary to extract the desired information. This process is known as chemometrics and uses algorithms such as Principle Component Analysis (PCA) and Partial Least Squares (PLS) to use NIR spectra for both qualitative and quantitative analysis of the desired constituent of measurement.
NIR spectroscopy has a long history dating back to the discovery of the first non-visible part of the electromagnetic spectrum by Sir William Frederick Herschel in 1800.
Herschel was testing different filters to pass sunlight through and noticed that filters of different colors generated varying amounts of heat. Further experiments entailed passing light through a prism to measure the different colors of light and in the process, Herschel took a measurement just beyond the red end of the visible spectrum. He detected a temperature one degree higher than that of red light and concluded that there was an invisible form of light beyond the visible spectrum.
At the time, Herschel referred to this region as “calorific rays” and it was later renamed “infrared”. Until the 1950s, the use of NIR spectroscopy as an analytical technique was dormant and it took a backseat to other analytical methods.
Mid-IR spectroscopy gained acceptance in the 1900s after the work of William Coblentz, who was the first researcher to obtain absorbance spectra of pure substances and verify their usefulness for the identification of organic functional groups.
NIR spectroscopy was neglected for many years because spectroscopists could not find any attractive information in the NIR region which was occupied by broad, super-imposed, and weak absorption bands. The work of Karl Norris at the USDA Agricultural Research Center pioneered the use of NIR spectroscopy as a modern analytical technique.
Norris built his own spectrometer using tilting filters and figured out that by using a computer with the spectral data as the independent variable, predicting the composition of an agricultural material was possible by calibrating the instrument with the laboratory determined composition as the dependent variable.
A groundbreaking paper published in 1965 by Norris paved the way for the adoption of a two wavelength model which could abandon Beer’s Law as a prerequisite for quantitative analysis. The highly scattered transmission of NIR light prevents Beer’s Law from being an effective equation for analysis.
The same paper also pioneered the use of diffuse reflectance as a non-destructive technique in the NIR region, allowing for direct measurement of samples with minimal preparation and without any pre-treatment. Ultimately in the 1970s, Norris developed the first commercial NIR analyzers for measuring protein in wheat and moisture in flour.
After the door was opened, the 1980s saw rapid advancement in the use of NIR spectroscopy as an analytical technique. Developments in instrument improvement, data treatment and processing, and the use of chemometrics for calibration models (largely dependent on advancements in computers) paved the way for widespread use of NIR spectroscopy in numerous industries.
Agriculture, Food & Beverage, Pharmaceuticals, Chemical, Petrochemical, and Polymers are just some of the industries where NIR spectroscopy emerged as an important analytical technique. The advantages of being fast, non-destructive, and non-invasive with strong light penetration and requiring minimal sample preparation have made NIR spectroscopy the analytical technique of choice for many applications. It is especially well suited for measuring small amounts of water and C-H bonds. After the initial boom in the 1980s and 1990s in the development of NIR spectroscopy, the technique was prominent but primarily used for benchtop and laboratory measurements.
Technological advances in hardware and software have helped move the focus on NIR spectroscopy from use as an offline analytical tool to an inline method that can be used for process control.
The Process Analytical Technology (PAT) initiative by the FDA created the framework for designing systems that can be used analyzing and controlling an entire manufacturing process. While formal implementation of this initiative has been limited outside of the pharmaceutical industry, the principles of PAT and benefits of real-time analysis are recognized. They have long been used in the petrochemical and chemical industries and have been implemented at many leading human and animal food manufacturers.
Some of the advancements that have helped advance the use of NIR spectroscopy as a real-time analytical tool include improved fiber optics and probes, multiplexed instruments, pre-built calibrations, instrument portability, and web-based platforms that support database management, trend and quality control analysis, and real-time virtual instrument and software maintenance and support.
The sections on this website provide a comprehensive review and examination of how NIR spectroscopy is used in the animal food industry.
FT-NIR (Fourier Transform-NIR) is a technique used to simultaneously collect high resolution spectral data over the entire range of interest. There are significant advantages to this method over a dispersive spectrometer, which measures intensity over a very narrow range of wavelengths over time. This technique requires repeated measurements to obtain absorption spectra over the full range of interest.
FT-NIR spectrometers use a light beam containing multiple frequencies which is modified very quickly in a short period of time. This occurs by shining the light into a Michelson interferometer, a configuration of two mirrors. One mirror is fixed and the other moves to transmit and block different wavelengths of light. The raw data is the light absorption for each mirror position and processing is required to change the raw data into the desired spectrum showing the light absorption at each wavelength. The processing is known as a Fourier Transform and it converts displacement of the mirror (measured in cm and called an interferogram) into the inverse domain and resulting absorbance spectrum (wavenumber in cm-1).
FT-NIR spectrometers collect spectra in wavenumber (an inverse measure of distance/frequency) as opposed to dispersive NIR spectrometers collecting spectra in wavelength (a measurement of distance).
There are numerous advantages to using FT-NIR spectrometers over dispersive instruments. Both resolution and signal-to-noise ratio (SNR) tend to be higher for FT-NIR instruments. Higher SNR is the result of simultaneous wavelength collection as well as higher throughput. Wavelength accuracy is higher as well because wavelength is calibrated in FT-NIR instruments by passing a laser beam of known wavelength through the interferometer.
Wavelength calibration in dispersive instruments is dependent on the mechanical movement of diffraction gratings and this can lead to inaccuracy. Imperfections in diffraction gratings and accidental reflections can also lead to stray light in dispersive instruments, which is the radiation of one wavelength appearing in another wavelength in the spectrum. Because the wavelength is determined by the modulation frequency of the interferometer in FT-NIR spectrometers, there is no direct equivalent to the stray light that can be found in dispersive instruments.
The primary advantage of FT-NIR spectrometers is that instruments are inherently reproducible, which eliminates the need for method transfer of calibration models needed to analyze the spectra. The process of collecting spectral data and correlating reference values of the parameter of interest to the spectra using chemometrics can be time-consuming and reference tests can be expensive. When a calibration model is created using one dispersive spectrometer, it may not work on another spectrometer of the same type because of differences in the dispersive element.
One good example of this is AOTF spectrometers, which use a crystal modulated at different frequencies to disperse light into different wavelengths. Such instruments can never be reproduced due to the inability to duplicate crystals.
Calibration models can be transferred from one instrument to another using mathematical algorithms and software standardization. This process is known as method transfer. Method transfer can be difficult, time-consuming, error-inducing, and sometimes may not work at all depending on the type of spectrometer, especially when transferring to multiple instruments.
FT-NIR spectrometers require no method transfer between instruments, even when using calibration models made by a different vendor as long as the original instrument is also an FT-NIR spectrometer. This results in saving of time and resources, especially when deploying multiple instruments in a production environment.
NIR spectrometers offer a fast, non-invasive, and cost-effective method for testing parameters of interest in numerous industries. There is little if any sample preparation required and no sample destruction. No chemicals or solvents are required for use.
While NIR spectroscopy requires the creation of calibration models using chemometrics to correlate spectra to reference values, once these models are constructed the benefits are enormous. Multiple parameters can be measured with a single scan after models are created.
Reference testing in the food and beverage industries often consists of expensive and time-consuming tests like HPLC and wet chemistry tests. These tests require skilled technicians and if not performed on-site, the results can take a week or longer to obtain. Performing such tests in a real-time process setting is often impractical if not impossible.
Advances in the technology of NIR spectrometers and the Process Analytical Technology (PAT) initiative have led to the implementation of NIR spectroscopy as a real-time process control tool.
Various spectroscopic methods exist but NIR spectroscopy has proven to be the most suitable technology in many industries for measuring parameters of interest in both laboratory and process settings.
NIR offers the advantages of little to no sample preparation, deep light penetration into the sample, and no sample destruction. Minimal or no sample preparation reduces operator error and eliminates the need for the use of toxic chemicals and solvents.
Deep light penetration is especially advantageous for measuring natural products when samples are often not homogenous. Some methods are not suited to measure parameters of certain organic molecules as well.
NIR spectroscopy is very well-suited for qualitative and quantitative analysis of organic compounds. Water is highly absorbed in the near-infrared spectral range, which makes NIR spectroscopy able to accurately measure even small changes in moisture.
NIR spectroscopy is used in numerous verticals in the feed & forage and pet food industries for testing of raw materials, intermediates, and finished products. Depending on the type of instrument, it can be used as a portable handheld mobile tool, a laboratory instrument, or a process control tool to optimize the manufacturing process and reduce waste.
Variation of natural products presents an inherent quality control challenge in not only feed & forage, but across the entire agricultural industry. NIR spectroscopy can be used for initial raw material identification and quantification of parameters of interest. Such information is immensely useful for both buyers and sellers of feed & forage products as well for scientists who use feed formation for nutritional optimization of final products.
Composition analysis requires the construction of calibration models to measure specific concentrations of parameters. Fat, protein, moisture, and carbohydrates are examples of macronutrient organic parameters that have been measured in feed & forage products. Fiber and energy components are crucial in compound animal feed final products and these can be determined using NIR spectroscopy. Even salt concentration can be determined in some cases even though it is not an organic molecule. Salt has an indirect effect on water molecules in a sample.
An indirect correlation is acceptable when constructing chemometric models for use by NIR spectroscopy, but such models must be carefully analyzed to ensure that the analysis is legitimate. Color analysis is another example of an indirect correlation which has successfully been measured using NIR spectroscopy.
After raw material content analysis, NIR spectroscopy can be used at various points throughout the manufacturing process. Laboratory instruments can be placed at-line next to different points in the manufacturing process. While lab instruments give a big improvement over traditional testing methods, the real benefits come from using NIR spectroscopy as a real-time process and formulation control tool.
Fraud and adulteration are tremendous problems in the feed and forage industry. NIR spectroscopy has been used as a tool to identify and monitor adulteration in products. Adulteration can constitute many different forms and methods. While perhaps unintentional, improper representation of nutritional content in both raw materials and final products is a form of adulteration.
In the case of agricultural products, variation in the same batch of materials can cause this type of adulteration to occur. Misidentification of a product is another common form of adulteration. Adding cheaper ingredients or dilution is another method of adulteration.
In some cases, this can be dangerous and present a health hazard, such as adding melamine to products containing protein. Melamine mimics protein in standard wet chemistry tests and in this case, NIR spectroscopy not only presents a faster and cheaper method for adulteration identification, it presents a solution when standard testing will not work.
A high- profile incident of this nature occurred in China with the adulteration of dog food with melamine. If an adulterant is identified in a product using NIR spectroscopy, the sample can be sent off for further testing. Large-scale testing is often impractical using standard methods and using NIR spectroscopy can be a powerful screening tool for adulterant identification.
The use of NIR spectroscopy as a real-time process control tool has become more prevalent as advances in technology have moved the focus of new instruments from the laboratory to the process.
Process Analytical Technology (PAT) is a framework for innovative process manufacturing and quality assurance. Critical points and parameters during manufacturing of a product are defined and the process is designed in a way that such points and parameters can be measured using analytical tools and instruments for real-time process feedback and control. Such instruments must be able to measure on-line and in a non-invasive manner. Many vendors have developed instruments that are able to measure multiple points in a process with a single instrument, usually using optical fibers and probes.
PAT has become an important part of pharmaceutical as well as chemical manufacturing and is beginning to acquire a hold in the feed & forage industry. In the case of pet food, one of the largest and most prominent pet food companies has successfully adapted NIR spectroscopy for quality assurance. The project has been so successful that the technology has been shared with competitors in the interest of creating safer products for the entire industry, ultimately benefitting all manufacturers, customers, and the pets themselves.
Real-time feedback using NIR spectroscopy can optimize the use of materials as well as reduce or eliminate the production of material that does not meet specifications.