BUCHI and CEMSI: Partners in Integration

A rapidly rising consumer food company needed NIR technology to quickly test final product quality in their pilot plant R&D facility. The R&D team wanted an NIR to provide non-contact, process control measurements of food products passing rapidly by on a conveyor belt.  However, being a pilot facility, they desired adjustable and temporary mounting approaches to optimize measurements and accommodate relocations within the plant.

The BUCHI NIR-Online X-Beam, designed to be used with conveyor systems, was a clear fit for the job, and the BUCHI NIR specialists were able to precisely and automatically trigger measurements as products were passing under the sensor. However, installing the sensor at the conveyor while allowing for future relocation or adjustments was an immediate challenge.

Enter Brad Young, a Technical Sales Specialist for CEM Specialties, Inc. (CEMSI), who called a local engineering part shop and manufactured a mobile platform on the spot to start a month-long trial period ending with incredible results. The customer is now looking to implement BUCHI NIR-Online technology at production facilities worldwide. Additional projects in development for this customer include sampling incoming materials and in-process measurements at the extruders.

Brad Young, a Technical Sales Specialist for CEMSI, executes his engineering expertise at a customer site, building a customized solution for a feasibility study at a pilot plant. The platform he devised supported an NIR-Onlinen X-Beam sensor over a conveyor belt transporting finished food products.

While BUCHI has a team of service engineers and product specialists available to facilitate NIR method development, installation and implementation, certain scenarios arise where additional and rapid engineering expertise is needed. For that reason, BUCHI Corporation has formally teamed up with CEMSI to offer superior support to customers who need a customized engineering solution to successfully implement NIR-Online sensors into their process.

In this blog, we will explore: who CEMSI is, how this partnership works, and the benefits of the enhanced engineering capacity offers in combination with the robust NIR-Online Solutions portfolio offered by BUCHI.  To find out more, we interviewed Steve Di Muzio, Technical Sales Supervisor, and Gary Saunders, Vice President, Operations of CEMSI.

Who is CEMSI?

For over 25 years, CEMSI has been providing process and emission monitoring solutions throughout North America and internationally to various industries including cement, mining, power, as well as chemical and petrochemical. Our support services include system design, integration, service (including preventive maintenance and troubleshooting).

What kind of projects does CEMSI work on?

We have global experience ranging from large-scale projects like gasoline blending analysis in the petrochemical industry and full-scale process and emission monitoring solutions in the cement industry to small CO-O2 boiler applications for emission monitoring.  We can design very simple cost-effective solutions to more complex custom systems for the most demanding applications.

As an example, in the chemical and petrochemical industry, analysis of incoming raw material and final product have traditionally been done using gas chromatographs.  This technology is becoming dated, often requiring complex sample systems and shelters to house this equipment, not to mention the lengthy delay for analysis.

How much do the innovations of BUCHI NIR being introduced by CEMSI to some of these older methodologies typically save the customer? 

In addition to the cost of the Gas Chromatograph (GC), you would require the sample system, shelter, integration of equipment into the shelter, crane to install shelter into place to name a few. There are additional on-going costs like heating and cooling the shelter housing the GC system.  The BUCHI spectrometer mounts directly on the process, circumventing these costly additions.  Based on hardware cost alone, we could easily estimate an $800,000 savings per installation.

Moreover, the process GC cost of ownership can approach 1,500 man hours and about $50,000 in preventative maintenance and emergency repair parts per year per unit. In comparison, the BUCH NIR consumes about 16 hours and $2,000 in preventative maintenance parts per year per unit.

What other markets do you think could benefit from these new NIR approaches?

  • Chemical manufacturing
  • Petrochemical refining
  • Cement
  • Food & beverage
  • Natural gas
  • Biofuels

How does the BUCHI-CEMSI partnership benefit the customer?

CEMSI is always looking for innovative ways to help improve our customers’ processes. We strive to help them save money through process optimization, reduction of maintenance time and cost. Our team has had opportunities to help our customers realize savings by reducing their product giveaway through improved analysis.  

The BUCHI NIR-Online system gives CEMSI the opportunity to achieve our goal of helping our customer save money, increase sampling frequency and measurement accuracy. Many industries continue to use old measurement techniques that often take several minutes rather than seconds to get a data point.  With the BUCHI NIR-Online technology, the customer will have the ability to get a lot more data points in the same amount of time that they were getting a single data point. This can be very useful to see trends and make necessary process adjustments on the fly. With this, the customer can minimize product giveaway, and ensure their final product meets the specification tolerances.

The NIR-Online X-Beam is one of several NIR-Online product configurations available. Each unit is ingress protected (IP65, IP66k) with optional Class 1 Div 1, ATEX, and CSA certification (gas and dust). Shown here in an “up-view” configuration, this versatile sensor can be adapted to accommodate many installation scenarios or requirements, including the addition of VIS and camera options to expand analytical capabilities.

Leveraging CEMSI experiences with integration, installation, troubleshooting and repair in tough applications with the BUCHI NIR-Online analyzer provides a simplified installation for the customer, directly in the field or on the production line.

BUCHI Application Specialist, Mark Sullivan, works alongside CEMSI Technical Sales Specialist to optimize data collection frequency and measurements of finished food product parameters including fat, protein and moisture.

BUCHI has a solid product and most installation will be straight-forward. However, there are some applications that will require out-of-the-box thinking to allow the NIR analyzer to maintain its intended purpose of being an easy to install, easy to use, easy to maintain, real-time data generating analyzer.

Partnering with BUCHI allows us to use our wealth of industry knowledge, combined with a high-quality product, to provide turnkey solutions to our customers. It is exciting to be able to offer customers a system that offers real-time analysis of their incoming raw material and their final product and be able to adjust processes to improve their product quality.

Fall is Doughnut Season (add an NIR for the perfect Baker’s Dozen)

In the northeast, fall ushers in crisp, cool air, vibrantly colored leaves… and doughnut season.

Perfectly glazed Krispy Kreme Doughnuts

Whether you’re getting your round, deep-fried cake from roadside from the Pennsylvania Amish or from a commercial bakery, quality is key. Krispy Kreme has been serving up delicious doughnuts for generations in the USA and even across the globe, so you may have heard of them. Their mission statement says in no uncertain terms: To make the most awesome doughnuts on the planet every single day.

Most doughnut aficionados believe that Krispy Kreme does make the most awesome doughnuts on the plant. So, the question becomes: how do they execute that mission statement with such incredible consistency? The BUCHI Studios team took a little road trip to their plant in Winston Salem, NC to find out.

The Winston Salem plant prepares the powder blends that will ultimately be used to create “sweet fluffy clouds of deliciousness” in Krispy Kreme bakeries throughout the USA, as well as the concentrates, or key powder ingredients, used in bakeries around the globe. The Quality team is focused on providing consistency in their mixes to ensure that sweet taste experience from Nibley, Utah to England or even Thailand. Near-infrared (NIR) spectroscopy has become an important measurement tool to that end.

“Anything coming in… we want to be able to test it as quickly as we can as soon as we can, so that we know all the way through the process it’s already been tested, it’s been approved, it’s okay and we can continue.

Rob Paxton, Krispy Kreme Donuts

The use of NIR to provide quantitative or qualitative measurements on flours or even proprietary mixes is not new, and its prevalence in the industry is a consequence of the technique’s very fast measurement times (from fractions of a seconds to seconds) that simultaneously deliver critical sample properties like moisture, protein, fat and ash, to name a few.

NIR is used at Krispy Kreme to ensure that incoming ingredients meet specifications before entering the process, to monitor critical parameters (like moisture, protein and fat) during blending, and to ensure that the concentrates meet stringent quantitative criteria before being shipped to bakeries worldwide.

Krispy Kreme plant worker empties bag of flour to be used to for proprietary powder mix.

BUCHI offers three NIR products to meet the needs of flour millers and bakeries. Of those, Krispy Kreme has implemented the NIRMaster and NIR-Online. The NIRMaster is a rugged, at-line NIR product with hygienic design well-suited for the food industry. This Fourier-transform (FT) NIR product is designed to provide the ultimate in spectroscopic performance, enabling exceptionally accurate and consistent sample measurements. The NIR-Online is an NIR product of extreme ruggedness that can be directly attached to process equipment like hoppers or blenders, or suspended over conveyors, and provide real-time process monitoring feedback. The difference between the dispersive NIR technology of the online sensor and FT-NIR was drawn out in a prior blog, however, both technologies have an important role to play in food processing and testing.

krispy kreme testimonial

Dollars to donuts, NIR can provide reliable measurements that can support quality control and production… but don’t take our word for it! Watch the Krispy Kreme customer testimonial.

More on: the use of NIR in milling and bakery

Quality control of raw materials and ingredients

At uploading bulk flour or at bakery sites, NIR can be used to prevent unsatisfactory loads of raw materials, check that shipments conform to specifications, determine the quality of whole and ground grains, and quantify important factors of raw materials for better quality of finished products.

Quality control of bakery mixtures and dough

At a production site, NIR can be used to predict flour yield, water absorption and dough development time, quantify baking mixture ingredients or composition (e.g. %-moisture, %-protein), determine ash content affecting baking performance, and determine starch damage and water absorption during the milling process.

Quality control of finished products

At a production site or packing area, NIR can be used to control the quality of finished products (e.g. bread, biscuits, flour, confectionery, pasta and breakfast cereal), ensure compliance with any statutory composition requirements (e.g. moisture content of bread), or provide data for nutritional labeling.

Learn more: webinar

To learn even more about how NIR is used in flour milling (the backbone ingredient for bakery applications), you can check out the streaming webinar below.

Do-nut Fear: NIR Quick-Start is Here

For those flour or bakery producers who are interested in following in the sweet footsteps of the Krispy Kreme NIR program, BUCHI offers a broad portfolio of quick-start pre-calibrations to start collecting measurements of common ingredients right away. For the more customized blends, we have NIRWare software and Auto-cal to support the NIRMaster and NIR-Online method development, respectively. We have Application Specialists to support training for in-house calibration development using NIRWare. For online applications, AutoCal is a simple push or click button allowing to directly time stamp a sample. The sample is manually collected up- or downstream (with the optional by-pass sampler a time stamped sample is even automatically collected!) at a sampling point and subjected to internal or external reference analytics. Afterwards resulting values (e.g. protein, moisture and fat mass percentage) are directly entered into the software and the calibration is automatically updated.

Auto-cal is also integrated into the operating software of the BUCHI at-line NIR product ProxiMate which is a great fit for the food industry due to the ease of use, ruggedness and hygienic design.

Measuring a flour sample on the new BUCHI ProxiMate at-line NIR system.

Visit our NIR Applications Finder to configure your solution based on the ingredients or products that are important to you, download the NIR Milling and Bakery Applications brochure, or contact us to discuss your applications.

Finding the right fit: FT vs Dispersive NIR

The longest continuously running mountain biking series in the United States is hosted in southwest Pennsylvania. Every year, hundreds of locals show up to test themselves in the 5-race series and vie for the title of “local hero.”

Races each take place at different venues, and each venue has a signature “wrench” to throw at riders, ranging from long, strenuous climbs to short but incredibly steep kickers, jagged rock gardens, jostling roots and log jumps, hair-raising descents, and (sometimes) even some smooth, flowing singletrack.

So what’s the point and how does this have anything to do with NIR?

The series champs are the best all-around riders. Top riders are often the most physically fit, yes, but they also are the most prepared. Oftentimes, they have to bring different bikes to best-match the terrain of any given race to get an extra advantage. They bring their fat-tired bike to glide over the rock gardens, or their narrow-tired, lightweight bike to pull away from the competition in the cyclocross race on the dry, grassy field. They bring their full-suspension bike to the downhill race, and their favorite geared bike to the climbing course.

The point is… the equipment (i.e. bike, NIR technology) you bring to the table should best meet the challenge (i.e. race course, NIR application) to perform at the best possible level and achieve the best possible result.

BUCHI offers four different NIR products, the NIRFlex N-500, NIRMaster, ProxiMate and NIR-Online, to meet different challenges or needs, including: application flexibility or difficulty, sampling location, sampling speed, or equipment ruggedness. To meet those requirements with the best advantage, BUCHI NIR products are engineered using one of two technologies: Fourier-transform (FT) and dispersive NIR.


An FT-NIR, or Fourier Transform NIR, uses an interferometer to modulate the NIR signal and a computer to obtain the spectra of materials.

The simplest form of an interferometer is the classical Michelson, which consists of a beamsplitter and two mutually perpendicular plane mirrors–one which remains static and one which moves. The beamsplitter reflects part of the NIR energy from the source (typically a halogen bulb) onto each mirror. The reflected beams are recombined at the beamsplitter and directed out. When the distance between the beamsplitter and the two mirrors is equidistant, the two beams interfere constructively. The interference between the beams with an optical path difference (i.e. as the moving mirror is displaced) creates an interferogram. The mathematical treatment called Fourier transform is used to convert the interferogram to a spectrum.

Advantages of FT-NIR polarization inteferometer:

  • Simultaneous measurement of all wavenumbers and greater light throughput, giving an improved signal-to-noise ratio
  • High wavelength resolution, leading to good data transferability (i.e. calibration transfer) and improved selectivity for spectral features with narrow bandwidth
  • Single-beam interferometer without typical double-beam divergence for mechanically and temperature stable beam alignment*
  • More robust design than standard Michelson interferometer*

Because there are fewer optical components to attenuate radiation, more power reaches the detector, providing the benefit of better signal-to-noise ratio. Because the resolution at discrete wavelengths is much better, elements which interact within very narrow bands can be detected (i.e. better selectivity).

* The additional benefits of insensitivity to vibration and robustness are realized with the BUCHI polization interferometer used in both the N-500 and NIRMaster products. This benefit in rough environments is attributed to the difference of spatial movements and the optical path shifts for the two light beams in a birefringent crystal of variable thickness. Whereas in a Michelson type interferometer mechanical distortions directly affect the interference, such effects are reduced by a factor of 10 to 20 in a crystal interferometer.  

In addition to displaying the performance benefits of FT-technology, the BUCHI NIRFlex-N500 product is a good fit for an R&D setting or lab where the sample types are varied (e.g. liquids and solids). The N-500 has hot-swappable sampling modules (e.g. fiber optics, solids and liquid measurement cells) and sampling add-ons (e.g. petri dish holders and 6-position vial carousels) to optimize method performance across a variety of applications.

The BUCHI NIRMaster blends the performance of FT-technology with the more rugged demands of at-line installation points. The NIRMaster is the world’s first dedicated FT-NIR standalone spectrometer available in food-grade PMMA or stainless steel. The accuracy and reproducible performance of polarization FT technology plus the hygienic design with certified dust protection (IP64 or IP65) meets the easy cleaning processes requested for at-line machinery.

As mentioned previously, the optical bench for the N-500 and NIRMaster are the same. While the N-500 isn’t suitable for at-line work due to the risk of ingress, both products have a similar robustness to mechanical disturbances.

However, when an application doesn’t require the level of spectroscopic performance delivered by FT to deliver acceptable property measurement accuracy, or when ultra-fast measurement speed or online measurements are required, then users should look to dispersive NIR technology.

Dispersive NIR

In a dispersive NIR system, light is constantly emitted from an NIR source (typically a tungsten halogen lamp) onto a sample. The diffusely reflected light from the sample is directed to a dispersive element (e.g. stationary grating) and the resulting spatially distributed monochromatic light is detected. In lieu of a moving monochromator and a single detector, a diode array may be used. A diode array usually consists of 256 diodes, each of which collects the intensity of a certain wavelength range depending on its spatial position.  These individual diode signals are commonly referred to as pixels. Division of measured intensity (I) by intensity of a white reference spectrum (I0) as well as conversion of pixels to a wavelength scale results in a so-called spectrum, I/I0 plotted against nm or cm-1.

advantages of dispersive technology

  • Measurement speed
  • Ruggedness

Utilizing diode arrays gives rise to detecting a specified wavelength range in milliseconds. Averaging up to 200 spectra per second improves signal-to-noise ratio and allows detection of fast moving products in pipes or on conveyor belts. Because diode array based process analyzers do not contain any moving parts, they are robust by design, making them suitable for rough industrial conditions such as vibrations, extreme temperatures or humidity.

Example non-contact sensing of powder moving along a conveyor belt using NIR-Online.

In a process environment diode array process analyzers are desirable over scanning or interferometer based technologies. Rotating wavelength filter wheels or Fourier Transform (FT) spectrometers with moving parts require longer measuring times and the quality of measured data relies on stable measurement conditions.

The BUCHI NIR portfolio offers two products using diode array technology: the NIR-Online process analyzer and the standalone at-line ProxiMate NIR.

The ProxiMate was born out of a call for a lower-cost and higher IP-rated at-line solution for food and feed applications. The IP-69 designation of the ProxiMate indicates complete protection against dust particle up to 4 microns in size and protection from water projected from a powerful nozzle in any direction. The instrument can be washed down in exactly the same way as other plant machinery.

Like the NIR-Online, the ProxiMate delivers fast measurements, enabling greater throughput and less downtime in the lab or on the plant floor. Because the optical bench of the NIR-Online and ProxiMate is identical, data and calibration transfer could also provide faster method transfer from at-line to on-line applications or vice-versa.

Making your selection

Here are some additional factors to consider when it comes to finding that “perfect fit:”

Spectroscopic performance – as dictated by the application. Some applications require higher spectral resolution FT to observe small peak shifts or narrow bandwidth features, while the desired accuracy for other measurements can be easily obtained with a dispersive diode array system.

Sampling considerations (i.e. type(s), frequency, volume, location). If an R&D lab needs to optimize sampling for liquids, solids and slurries, then having the flexibility of a laboratory instrument, plus the benefits of optimal spectral resolution, would lead the user to an FT-NIR like the NIRFlex N-500. When sampling volume and/or frequency requirements are moderate, sample variation is low (i.e. you don’t need to optimize measurement conditions for drastically different materials like slurries, clear liquids and powdered solids) and measurements are more practically done on the plant floor, then an ingress protected NIR solution is advantageous. When sampling points are potentially hazardous or impractical, or when an ideal sampling frequency is very high or continuous, then an in- or online NIR product that is integrated into the processing equipment is clearly the better fit.

Cost and payback. In general, the cost of a diode array instrument is less than an FT-NIR product. Payback can be determined based on the frequency or cost of wet chemistry methods, the reduced sampling time of the NIR method over alternative methods, or mitigating the risk of a failed or recalled batch or accepting out of spec raw materials. Moreover, if an application exists as an out-of-the-box solution (e.g. a “pre-calibration” for moisture, protein and fat in ground meat) then the cost of method development will decrease sharply.

Certifications & standards. Consider whether the installation points or application requires food-grade materials, explosion-proof design, GMP or non-GMP software before making a decision. For example, the BUCHI NIRMaster, ProxiMate and NIROnline products are considered safe in food environments. The BUCHI NIRFlex N-500 and NIRWare software package offers 21 CFR Part 11 compliance and IQ/OQ, whereas the other products do not. The BUCHI NIR-Online® ExProof process analyzer is constantly over-pressurized, eliminating the risk of flammable gas penetration.


Just as a mountain bike race would best handled on a mountain bike… there are well-suited NIR products to handle specific application and workplace requirements. Need some more help getting matched up? Contact us.

Supporting References

Skoog, D. A., F. J. Holler, and T. A. Nieman. 1998. Principles of Instrumental Analysis, 5th ed. Chicago, Ill.: Harcourt Brace College Publishers

Burns, D.A., Ciurczak, E.W. 2007. Handbook of Near-Infrared Analysis, 3rd ed. CRC Press.

BUCHI Product Pages

NIRSolutions Product Page

NIR-Online Product Page

Things are really getting cheesy at BUCHI.

When prodded, I suppose many at BUCHI would agree that some of the cheesiest members of the team belong to the NIR group.

Maybe that’s something to be proud of!

More cheese, please!

Cheese is delicious, after all. With a global market of around $100 Billion USD, I think there is a general agreement on the matter.

There are many ways to consume cheese, of course. Processed cheese products like fondue have their place on the cheese continuum, particular around special events like graduation parties and weddings that seem to dominate our summer calendars.

Manufacturing processed cheese products like fondue is a complex task, with special emphasis on key quality parameters like total solids and fat content.

These products are typically produced by blending one or more shredded natural cheeses with additional ingredients, such as: emulsifying salts, condiments, flavors and other goodies. This mixture is then heated and sheared until a homogeneous molten mass is obtained which can be poured into heart- or graduation-capped shaped molds or other shapes for future devouring.

In order to consistently deliver the same great-tasting product, real-time control of key quality attributes is a must. Monitoring total solids content, fat, salt, pH, homogeneity and more during a blend can allow for real-time process adjustments to meet all of the quality targets and avoid having to rework a batch. The end result: tasty cheese products (read: make money) and improved manufacturing efficiency (read: save money).

While traditional laboratory methods exist for determining the quality parameters, issues with representative sampling and the method collection times are rate-limiting.

Want to learn more? Contact Us and request Short Note #357, or ask to speak with an Applications Specialist to learn more about how you can implement NIR for better process control in cheese manufacturing.

You can also visit our NIR-Online Solutions page to learn more.

If cheese quality is on your mind, but an on-line solution isn’t a good fit, BUCHI also has milk & dairy solutions for our off-line and at-line NIR. You can use our NIR Applications Finder on-line tool to configure the perfect NIR solution for you. Choose your industry and products, then get a full listing of available pre-calibrated applications, plus a quote.

Among our pre-calibrated parameters, you’ll find: dry matter, moisture, fat, protein, lactose, fatty acids, total sugar, ash and more.

Use our new NIR Application Finder to get the latest in Pre-Calibrated Solutions for your industry.

Interested in an application that isn’t listed? Fear not! We have a team of Application Scientists at the ready. Reach them using our Application Support Request Form .

If you’re looking for the full gamut of our published cheese & dairy applications, check out the BUCHI Application Finder. You’ll find methods related to:

  • Extraction
  • Spray Drying
  • Kjeldahl for protein determination
  • Near-infrared spectroscopy

Stay cheesy, my friends!

Quality is Going to the Dogs.

Don’t worry, it’s a good thing.

This week, BUCHI Product and Application Specialists mingled with pet food suppliers and manufacturers at the Petfood Forum 2019 in Kansas City, MO. Some key topics on deck for event speakers include nutrition, labeling, product development, safety and manufacturing.

BUCHI Laboratory Solutions can help keep the fur kids happy and healthy.

Did you know BUCHI has its paws in the formulation, quality control and labeling aspects of the pet food industry?


Our spray dryer and freeze dryer equipment can be used to develop innovative, nutritious and shelf-stable products for happy, healthy pets. These technologies have been used to optimize stability and bioavailability for pet food ingredients, including: natural products, amino acids, proteins, vitamins and oils.

Quality Control

WATT Global Media conducted a survey and identified raw material ingredient quality as the top concern among surveyed Petfood Forum registrants. BUCHI provides expertise and laboratory and process equipment which helps to address quality standards at various stages along the pet food value chain, from raw material intake, to in-process quality control, to finished product testing to validate label claims.

The multi-axis plot shown below is a type of decision tree to determine which is the most appropriate method to select for protein determination, comparing Kjeldahl (red line), Dumas (yellow dashed line) and NIR (blue dashed line). For example, if your current need is for a high-speed analysis with a small environmental footprint, suitable for moderate sample type variation, then NIR is a good choice. If labeling compliance is of chief concern, with potential to adapt methods to broad variation in sample types, then Kjeldahl is a better selection.

Raw material inspection is an important component of a quality control program. Understanding the actual quality and parameters of incoming materials can help avoid process or nutritional deviations that occur because of out-of-spec ingredients. There is also an economical component: formulate closer to target and minimize issues like “protein give-away,” or avoid product recalls due to mislabeled or contaminated ingredients.

Near-infrared spectroscopy is one tool in the analytical toolbox that has been useful for establishing quality in raw ingredients, from grains to raw meats. The speed of analysis is well-suited for a quick quality check against Certificates of Analysis upon receipt of supplied goods.

Typical parameters measured by NIR in meat products include: protein, fat and moisture. For meat applications, color, pH, salt, starch and collagen content may also be implemented. These and other calibrations may be further refined with the addition of samples representative of the ingredient suppliers used within any production scheme.

Click to view a webinar highlighting ways to manage pet food production & quality using NIR

Properties of raw meat ingredients can be monitored at the time of their production, with installation points over a conveyor belt, directly in product pipes or processing equipment including deboners, grinders or mixers. An example of online measurements of protein, moisture and fat content of minced meat at a mixer has been described in a BUCHI short note . These same calibrations can be applied in-line or off-line for the pet food manufacturer who sources meat from a supplier. Large premium meat producers such as Mircana have successfully implemented this equipment to make real-time corrections to processing deviations at the mixer.

Watch this short clip to see how single or multipoint inline NIR sensors can help you control your production process


Kjeldahl is the most established reference method for protein determination in feed, and commonly serves as a reference for NIR. You can find applications for protein and fat determination by Kjeldahl and Soxhlet extraction using our BUCHI Application Finder. Some of the content you’ll find includes:

The BUCHI Booth at Petfood Forum is getting packed up later today. If you missed us, Contact Us to schedule a chat with an Application Specialist, or even a virtual demo!

NIR: a Spring-y subject

Winter felt brutal and eternal, as it always does for someone who doesn’t ski or care for hot chocolate, I suppose. What a relief it is to see signs of Spring emerging from my brownish-colored yard and hear birds chirping outside once again.

Did you know NIR is quite Spring-y as well. This blog will explore some spring-themed theory.

beautiful bird bloom blossom
Photo by Pixabay on Pexels.com

At temperatures above absolute zero (i.e. even in the dead of a Northeast USA snowmageddon), all of the atoms in a molecule are in continuous vibration with respect to each other.

The behavior of molecular vibration is analogous to a mechanical model in which two masses connected to the ends of a spring! A disturbance of one of these masses along the axis of the spring results in a vibration called the simple harmonic oscillation.

close up of metal
Photo by Pixabay on Pexels.com

Vibration, or the displacement of an atom relative to its equilibrium position, produces potential energy proportional to the work required to displace the mass.  This energy is at its maximum when the spring is stretched or compressed to its maximum amplitude. It is at its minimum (i.e., zero) at the equilibrium position.

The fundamental requirement for infrared (Far-IR, mid-IR, near-IR) activity, leading to the absorption of infrared radiation, is that the energy of incident radiation matches the vibrational energy levels exactly, and that the vibration itself causes a change in dipole moment.  The frequency of radiation that will bring about this change can be calculated by Hooke’s Law:

Hookes Law

where c is the speed of light (3×103 cm/s), f is the force constant of the bond (dyne/cm), and Mx and My are the masses of  the atom x and atom y involved in the bond, respectively.  The force constant is positively correlated to properties such as bond order or bond strength (i.e. the “springiness” of the bond).  In accordance with the Boltzmann distribution, frequencies which correspond to fundamental transitions between the ground state and first vibrational level (n = 1) dominate the vibrational absorption spectrum.  Because the majority of absorption bands of chemical compounds correspond to fundamental vibrations at infrared frequencies, it is a common tool for structural elucidation.

How does thee vibrate? Let me count the ways.

The number of possible or theoretical fundamental vibrations is determined by the total degrees of freedom of the molecule.  Each atom requires three degrees of freedom in order to describe its position relative to other atoms in the molecule.  Therefore, a molecule of N atoms has 3N degrees of freedom.  For nonlinear molecules, six degrees of freedom are used to describe translation and rotation; the remaining 3N – 6 degrees of freedom are vibrational degrees of freedom (i.e., fundamental vibrational modes).  For linear molecules, only two degrees of freedom are required to describe rotation, resulting in 3N-5 normal modes.

Disclaimer: Sometimes 1+1 doesn’t equal 2

The number of theoretical bands will not necessarily equate to the number observed experimentally.  The number of theoretical bands observed may be reduced by: lack of a change in the molecule’s dipole as it vibrates or rotates, fundamental frequencies that fall outside of the infrared region or are too weak to be observed, vibrations that coalesce, or the occurrence of a degenerate band from several absorptions of the same frequency in highly symmetrical molecules.  On the other hand, vibrations at integer-multiples of a given frequency and combination tones will increase the actual number of bands observed.  It is from the combination and overtones transitions that NIR spectra arise.

The NIR region of the electromagnetic spectrum covers the range of approximately 14,000 to 4,000 cm-1, or about 700 to 2,500 nm.   The most prominent absorption bands occurring in the NIR region include overtones and combinations of fundamental vibrations of the IR-active –CH, –OH, -CO, –NH and –SH functional groups present in most pharmaceutical drug molecules.  Due to the relatively weak molar absorptivities of the transitions responsible for the peaks observed, sample dilution is not required.  This characteristic also provides for relatively deep sample penetration up to several millimeters thick, especially at shorter wavelengths (e.g., 700-1500 nm).  Even though NIR spectroscopy is characterized by spectra which are typically broad, overlapping and of low intensity relative to the fundamental mid-IR absorption bands, it has some practical advantages.  The richness and utility of NIR spectra is a consequence of anharmonic oscillation.

Anharmonicity: where the simple rules start to break down and things start to get interesting

Bonds which share a common atom seldom behave as independent oscillators.  As the interatomic distance separating two atoms decreases, coulombic repulsion between the nuclei results in an additional force which acts in the same direction as the force restoring the system toward equilibrium.  Thus, the potential energy of the system increases more rapidly than predicted by the harmonic oscillator.  On the other hand, as the interatomic distance approaches that at which dissociation of the atoms takes place, a decrease in the restoring force and potential energy of the system occurs.  The intramolecular interactions produce non-symmetric vibrations about the equilibrium position.  The anharmonicity results in non-equivalent energy changes between vibrational states, where ΔE becomes smaller at higher quantum numbers.   Moreover, the selection rule is not rigorously followed (because rules are made to be broken), thus allowing the overtones responsible for much of the NIR spectra, where Δn = ±2, ±3 and ±4 represent the first, second and third overtones, respectively.

The degree of anharmonicity determines the extent of the displacement from an integer multiple of the fundamental frequency, as well as the intensity of the overtones.   Vibrations stemming from intramolecular hydrogen-bonding vibrations have the highest anharmonicity constants, leading to their prevalence and high intensity in the NIR region. That’s why NIR is so great at measuring low levels of water in samples!

More interesting stuff in the spectra:

NIR spectra are further enriched when vibrational modes interact to give absorptions at frequencies that are the approximate sums or differences of their fundamental frequencies.  These combination bands, which generally occur between 1900 and 2400 nm, are a consequence of energy absorption by two bonds rather than one, allowing the photon to excite two vibrational modes simultaneously.  As with overtones, the intensities of combination bands are weaker than their fundamental frequencies.

A special type of interaction called Fermi resonance occurs as a consequence of accidental degeneracy of different vibrational modes have the same symmetry and approximately the same frequency as a fundamental vibration.  This results in two relatively strong absorbance bands which are displaced at slightly higher and lower frequencies than expected, respectively.

Darling and Dennison resonance affects vibrations which have identical symmetry species and similar energies, leading to several pairs of absorption bands.

Coupling between oscillators results in slight to moderate shifts in the absorption frequency of the molecules involved.  In general, coupling requires that vibrations be of the same symmetry species and a common atom or bond between the two vibrations or vibrating groups, respectively.  The interaction is greatest when the coupled groups have nearly equivalent energies; little to no interaction is observed by groups separated by two or more bonds.  Despite the fact that coupling leads to uncertainties in functional group identification, it is this phenomenon that provides the unique features of a spectrum enabling compound identification.


For more reading on this spring-y subject:

Skoog D.A. and Leary J.J. Principles of Instrumental Analysis. 4th Edition. 1992.

Silverstein R.M, Spectrometric Identification of Organic Compounds, 5th Edition. 1991.

D. Burns, and E. Ciurczak,Handbook of Near-Infrared Analysis 2nd Edition, Marcel-Dekker, Inc. New York, 2001.

E. Ciurczak and J. Drennen, Near-Infrared Spectroscopy in Pharmaceutical and Medical Applications, Marcel-Dekker, Inc. New York, 2002.

L. Weyer and S.-C. Lo, “Spectra-Structure Correlations in the Near-infrared,” In Handbook of Vibrational Spectroscopy, Volume 3, Wiley, U.K., 2002.



Evolution of BUCHI NIR

February 12 was Darwin Day. Darwin, of course, was known for his theories of evolution. While his theories continue to be hotly debated 137 years after his passing, none could argue that products and companies must evolve in some capacity to keep pace with, and meet the demands of customers-at-large.


Borrowing the words of Spanish soccer player Gerard Pique, “Evolution is all about looking forward.” The BUCHI NIR portfolio shows evidence of evolution in that sense. 

The BUCHI NIR “big bang” occurred in 1999 with the acquisition of Buhler NIR, with incremental steps leading up to the dramatic upgrade to the NIRFlex series, and so far culminating with the N-500 FT-NIR product.


The NIRFlex bench-top instrumentation was designed to meet consumer demands in both R&D and routine testing labs for true flexibility and high performance. Hot-swap modules accommodate nearly any sample type (i.e. solid, liquid, semi-solid or slurry), while the Fourier-transform (FT) technology provides exceptional precision. A novel single-beam FT design further propels instrument performance, stability and robustness, while hardware and software components continue to meet even the demands of the  pharmaceutical regulatory agencies.

NIRMaster_NIRMaster_ProNext, the NIRMaster was added to the portfolio specifically to serve the demands of the food and feed industries, bringing with it IP-54 and IP-65 ingress protection and features designed to ensure food safety. This revolutionary design was the first to marry the accuracy of FT-NIR with a robust and hygienic standalone at-line design suited for the production floor.


In 2005, the BUCHI portfolio expanded with the acquisition of German on-line sensor manufacturer NIR-Online, just a modest train ride away from company headquarters in Flawil, Switzerland. With this acquisition, BUCHI was finally able to offer a true in- and on-line NIR solution for process control. Since its introduction, the NIR-Online product has further evolved, expanding capabilities to include multiplexing, and continuing to meet requirements for workplace safety, including explosion-proof options for hazardous environments.

In late 2018, the BUCHI NIR portfolio saw its next evolution: the ProxiMate. This at-line workhorse took the speed and agility of the NIR-Online solution at-line, creating an affordable option for the typical food and feed industry customer without compromise in quality or performance.

ProxiMate_masterProxiMate offers 3 main benefits for food and feed industry users: applicative fit, extreme robustness and simple operation.

  • BUCHI application chemists have developed many ready-to-use pre-calibrations typically required by the food and feed industries, enabling accurate results with minimal effort and by users of any ability level

Of course, the idea of the “survival of the fittest” comes to mind on Darwin Day. It seems that the more recent of our evolutionary steps in the NIR product portfolio has been hyper-focused on robustness–survival in the dirtiest, harshest, or most hazardous environments. Learn more about ProxiMate and join us on this Extreme Journey along the NIR evolutionary path!