Near Infrared Spectroscopy (NIR) for Greater Process Control

Although process optimization is widely recognized as a critical requirement of chemical production facilities, it usually stays an offline or at line task. There is clearly a requirement for more in depth process understanding via on-line real time analytical measurements as real applications undergo process disturbances and uncertainty.

Greater Process Control by Using NIR

Image credit: Art Photonics GmbH

When using optical analysis methods for in-situ applications, the observation window is the eye to the process. During chemical and biological processes, a clean observation window offers reliable analysis at any time. Therefore, optical methods can be used only when the following procedures are carried out at any time and in a reliable manner:

  • Cleanliness check of the observation window
  • Cleaning of observation window
  • Zero baseline at any time
  • Active control over the complete analyzer
  • Complete cleaning of all parts which have contact with product (surfaces, seals, etc.) following the guidelines of GMP, Hygiene, etc.

Greater Process Control by Using NIR

Image credit: Art Photonics GmbH

Application Examples

Refinery Production

The CH components of the samples control NIR measurements. As such, they are advantageous for the determination of high concentrations. In some cases, there is an advantage in measuring additional functional groups through MIR immersion probes that can monitor specific compounds. (Aromatic versus Aliphatic.)

Fuels

NIR transmission not only establishes the composition of bulk components but also enables the calculations of octane numbers. MIR in specific wave number ranges can be helpful for determining the additives and/or impurities.

Bio-Fuels

Process control can be done before and after purification in the production of bio-fuels. Generally, the NIR region contains overtone and combination information with the most sensitive bands being derived from O-H and C-H bonds. Again, additives and/or impurities can be determined by using MIR process control data from fiber optic immersion probes.

Solvents

MIR measurement is advantageous for compositional monitoring, especially when measuring process mixtures and looking for and confirming impurities.

Specialty Chemicals

ATR measurements and reflectance measurements can be used for pigments, dyes, water treatment and agrochemicals. While NIR would be largely used for bulk analysis, MIR would be extensively used for traces analysis.

Food Products

As this is a field where NIR has been used extremely well, any benefits provided by MIR would be for specific lower level compound analysis. There could be some scope for integrating MIR and NIR in the analysis of fermentations, flavors and fragrances. Moreover, there may be advantages of combining data, primarily in fermentation. Although some of the categories might have some scope for a transmission probe, but the majority requires a reflectance monitoring probe (e.g. fats, dairy and oils).

Pharmaceutical Products and their Development

Based on whether the material is a solid or a liquid, they are divided into two categories. For composition monitoring, a combination of wavelength regions in a reflectance probe can be employed where NIR fiber optics can establish the main components and MIR fiber optics can determine low concentration compounds.

Measurement Examples

Dairy production: wash cycle

Dairy production: wash cycle. Image credit: Art Photonics GmbH

Sunflower oil production monitoring

Sunflower oil production monitoring. Image credit: Art Photonics GmbH

Olive oil production monitoring

Olive oil production monitoring. Image credit: Art Photonics GmbH

Attenuated Total Reflection (ATR) Immersion Probe

Attenuated Total Reflection (ATR) Immersion Probe

Image credit: Art Photonics GmbH

An extensive range of fiber optic ATR Immersion Probes are available for process spectroscopy applications. High contrast evanescent absorption spectra in the temperature range of 0-140 °C are provided by sealed diamond or ZnSe tips.

Attenuated Total Reflection (ATR) Disposable Loop

Attenuated Total Reflection (ATR) Disposable Loop

Image credit: Art Photonics GmbH

As a cost effective substitute to diamond ATR-IR fiber probes, PIR fiber probes in the 3-18 µm range with detachable PIR fiber loops have been designed.

Lighthouse Probe

Lighthouse Probe

Image credit: Art Photonics GmbH

The Lighthouse Probe® is compatible with a wide range of spectroscopic techniques, including NIR and UV/VIS, to overcome the conventional problem of products adhering to observation windows. It is compact and easy to install, and allows a reliable in-process measurement of quality critical product features to be taken.

Ceramat® WA 150

Ceramat® WA 150

Image credit: Art Photonics GmbH

Featuring an automatic sensor lock-gate, the Ceramat® WA 150 is used for complex applications with ceramic sealing to the process. It remains reliably sealed off even when the process medium is under pressure, hot, toxic and corrosive.

SensoGate® WA 130

SensoGate® WA 130

Image credit: Art Photonics GmbH

SensoGate® WA 130 features a universal, pneumatically operated retractable fitting with a modular design. A central multiplug consists of tubings for rinsing, cleaning and calibration media, including check valves and limit switches, and enables a safe, fast and space-saving connection.

This information has been sourced, reviewed and adapted from materials provided by art photonics GmbH.

For more information on this source, please visit art photonics GmbH.

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