NIR spectroscopy services

NIR (Near Infrared) spectroscopy is a powerful tool for quantitative and qualitative analysis of liquids and solids. It is generally used as a secondary technique requiring a primary analysis method or the preparation of known standards.

Quantitative and qualitative models employ partial least squares (PLS) or principal component analysis (PCA) chemometric methods. The spectral range for NIR spectroscopy is 1100 nm to 2500 nm. Transitions in the NIR region are overtones and combination bands of high frequency fundamental transitions. In NIR spectroscopy, sample preparation is minimal. Pellets, powders and plaques can be analyzed as is.

Typical applications of NIR include:

  • Measurement of additive levels in polymer matrices
  • Compositional analysis of polymer mixtures
  • Material acceptance and quality control
  • At-line, in line and online material analysis

NIR spectra generally cannot be interpreted without a library of calibration spectra for comparison.  However, short acquisition times, minimal sample preparation requirements and automated chemometric data analysis provide rapid material evaluation appropriate for QC testing applications.


Our NIR scientists have more than 20 years of experience with vibrational spectroscopy techniques and have extensive expertise with a wide variety polymers and polymer additives, as well as extensive experience with implementing at-line, online and in line analytical solutions.

Arkema Analytical Services NIR specialty test services include:

  • NIR spectral acquisition
  • Composition relative to known standards
  • Pass/fail analysis for QC
  • NIR application feasibility studies
  • NIR analysis method development


NIR spectra of calibration samples

Pictured above is an NIR spectra of calibration samples with varying additives and structures analyzed by principal component analysis and partial least squares.  Principal component scores can be used for material identification. The partial least squares model allows for quantization of specific additive levels.