Why Metals Are Poor Candidates for NIR Analysis
NIR analysis is based on interactions between near-infrared light and molecular vibrations. It is most useful where the sample contains bonds such as C-H, O-H, N-H, or S-H that produce measurable absorption patterns.
Pure metals and many alloys are not molecular materials in the same way as polymers, foods, minerals with water content, or organic compounds. They are also often reflective, opaque, and optically unsuitable for generating useful NIR spectra. As a result, NIR cannot normally identify alloy grade or measure metal composition directly.
There may be cases where NIR can assess a coating, residue, organic layer, lubricant, or corrosion-related material on a metal surface, but this is not the same as analysing the metal or alloy itself. For direct alloy identification or elemental composition, XRF is usually the more appropriate technique.
Assessing NIR Suitability for Metallic Samples
For more detail on the method, review PAS’s overview of Near Infrared Spectroscopy technology. To compare available systems, explore PAS’s NIR analysers through Portable Analytical Solutions, or get in touch to discuss whether your material is suitable for NIR measurement.