Understanding NIR Material Limitations
Near-infrared spectroscopy is mainly used to measure molecular vibrations associated with bonds such as C-H, O-H, N-H, and S-H. This makes it useful for many organic materials, agricultural products, polymers, pharmaceuticals, minerals with water or hydroxyl content, and other materials with suitable molecular features.
Materials that are purely elemental, metallic, or inorganic with no relevant molecular absorption features are usually poor candidates for NIR. For example, NIR is not typically used to determine elemental composition in metals, alloys, or most dry inorganic salts because these materials do not produce the type of molecular spectral response that NIR relies on.
NIR can also be limited by sample presentation. Very dark, highly absorbing, highly reflective, coated, or optically dense materials may produce weak or distorted spectra. Mixtures can be analysed when calibration models exist, but NIR is not a universal identification tool and should be validated for the specific material, property, and measurement conditions.
Assessing Whether NIR Fits Your Application
For more details on the method, review PAS’s overview of Near Infrared Spectroscopy technology. To compare suitable instruments, explore PAS’s NIR analysers through Portable Analytical Solutions, or contact our team to discuss your material type and measurement requirements.
Meta description: Learn what materials cannot be analysed using NIR, including metals, elemental samples, dry inorganics, and materials with weak or unusable spectral signals.