Process NIR

Spectrometer System

• Fast-Precise-Robust

• Perfect for demanding process applications

• Modern detector array technology, no moving parts

• Various spectral ranges available from 190 nm to 2150 nm

• Permanently calibrated

• USB/Ind Ethernet interfaces connection to computers

• Standard SMA fiber-optic connection

• Easy connection to fiber-optic immersion probes and flow cells

What is NIR spectroscopy

• Near InfraRed Spectroscopy (NIRS) Absorption bands in the near infrared region: 750-2500 nm

• Usually weak and broad bands because of vibrational overtones and combination bands when two molecular vibrations are excited simultaneously. 

• The intensity of overtone bands reduces by one order of overtone for each successive overtone. 

• Usually high signal to noise ratio due to intense radiation sources and NIR is able to penetrate undiluted samples and use longer path lengths

• Fast measurement, very useful for rapid measurement of more representative samples

• NIRS is a secondary analytical technique. Chemometric model building needed for both qualitative and quantitative analysis

Advantages of NIR Spectroscopy 

• Fast measurement

• No sample preparation needed

• Non-destructive, non-invasive

• Suitable for in-line applications

• Measurement can be done through transparent
  containers and glasses 

• Sensitive to any molecule containing
  C-H, N-H, S-H or O-H 

• Qualitative and Quantitative analysis

Absorption & Transmission

• Quantitative analysis: concentration determination for transparent liquid solution

• Beer’s law
  The transmission of light through a solution of fixed pathlength is       proportional to the concentration.

• Transmission:     
  𝑇=𝐼/𝐼_0 =10^(−𝜀(𝜆)𝑐𝑑)

• Absorption:  

     𝐴=log⁡〖𝐼_0/𝐼〗=𝜀(𝜆)𝑐𝑑

• 𝜀: molar absorptivity as a function of wavelength
  c: concentration of the compound in solution
  d: path length of the sample, a fixed quantity defined by a cuvette diameter or sample probe gap

Diffuse Reflectance

• Signal generated from both absorbance and scattering.

• Concentration determination for solid samples, powders, and non-transparent medium

• Obtaining bulk properties such as density, viscosity, fuel octane number, fruit ripeness, etc.

• Determination of physical properties such as particle size, mechanical properties, molar masses of polymers, etc.

• Multivariate analysis – chemometric model is usually used due to complex nature of NIR spectral region
  Chemometrics – use of mathematical and statistical techniques for extracting relevant information from analytical information contained in the NIR spectral data
   

Transmittance Through Scattering

• Signal generated from transmission through scattering medium

• Concentration determination for solid samples, powders, and non-transparent media

• Determination of pharmaceutical API dosage in tablet – Content Uniformity (CU) 

• Providing volumetric info on solid sample that is more accurate than those generated from surface dominated diffuse reflectance measurement

• Multivariate analysis – chemometric model is usually used due to complex nature of NIR spectral region

• Chemometrics – use of mathematical and statistical techniques for extracting relevant information from analytical information contained in the NIR spectral data