Spectroscopy is the study of the interactions between matter and electromagnetic radiation. When an electromagnetic wave passes through a molecule, the molecule will absorb the energy at a specific frequency. Because different molecules absorb energy at different frequencies, the collected spectrum can be used to identify the materials as shown in Figure 1. QTA uses NIR (near infrared) spectroscopy and MIR (mid-infrared) spectroscopy technologies in its qualitative analysis services.
Mid-IR vs Near-IR
Mid-infrared (MIR) units are more sensitive than near-infrared (NIR) units at a spectral range of around 400-4000 and analyze non-diluted samples with only micrometers of pathlength. The QTA MIR units, QTA MRT and QTA MTC, are suited to test homogenous samples only. The QTA MRT unit has the ability to analyze a component concentration from 100 ppm up to 100%. NIR units are less sensitive than MIR, but can analyze a liquid sample from millimeters to centimeters. When scanning a solid sample, NIR can penetrate up to 3mm. QTA’s NIR system, QTA UM, is only suited for non-homogeneous samples and can normally analyze a component from 0.1% up to 100%. Neither MIR nor NIR can be used for trace amount analysis like ppb or low ppm.