NIR spectroscopy principle and selection guidelines

NIR (near-infrared) spectroscopy is a type of spectroscopic technique that uses light in the near-infrared region of the electromagnetic spectrum (wavelengths from approximately 750 nm to 2500 nm) to identify and analyze chemical compounds.  NIR spectroscopy is based on the absorption of light by molecules.  When a molecule absorbs a photon of light, the energy of the photon is transferred to the molecule, causing it to vibrate or rotate.  The specific vibrations or rotations that a molecule undergoes depend on the chemical bonds and functional groups present in the molecule.  By measuring the absorption of light at specific wavelengths, it is possible to determine the functional groups and chemical bonds present in a sample, and thus identify the chemical compounds that are present. 

In order to use NIR spectroscopy effectively, there are a few guidelines to consider when selecting the appropriate instrument and sample preparation techniques:             

• Wavelength range: Make sure that the instrument you are using has the appropriate wavelength range for the compounds you are interested in analyzing. NIR spectroscopy is most sensitive to functional groups such as C-H, O-H, and N-H bonds, which absorb light in the 750-2500 nm range.               

•  Sample preparation: It is important to prepare the sample in a way that allows for good transmission of NIR light. This may involve grinding the sample to a fine powder, using a transparent sample container, or suspending the sample in a transparent liquid.             

• Sample size: The size of the sample will affect the signal-to-noise ratio of the measurement. In general, a larger sample size will give a stronger signal, but it is important to find the optimal balance between sample size and measurement accuracy.                     

• Resolution: The resolution of the instrument will affect the ability to distinguish between closely spaced absorption bands. Higher resolution instruments will give more detailed spectra, but may also be more expensive.                   

• Sample stability: If the sample is prone to degradation or change over time, it is important to take the measurement as quickly as possible to minimize any changes that may occur.                           

By considering these guidelines, you can select the appropriate NIR spectroscopy instrument and sample preparation techniques for your specific application.         

Applications of NIR spectroscopy include: 

• Quality control in food and agriculture: NIR spectroscopy can be used to analyze the chemical composition of food and agricultural products, such as determining the protein content of grains or the fat content of milk.                   

• Environmental monitoring: NIR spectroscopy can be used to analyze the chemical composition of water and air samples, allowing for the detection of contaminants and pollutants.         

• Pharmaceutical analysis: NIR spectroscopy can be used to analyze the purity and potency of drugs, as well as to identify impurities and contaminants.         

• Industrial process control: NIR spectroscopy can be used to monitor and control industrial processes, such as the production of plastics and chemicals.

Aurora Pro Scientific offers a full line of NIR spectrometers.  If you have any questions, please feel free to reach out to us at:  sales at auroraprosci dot com!