Foreign material analysis by [Mixture Analysis]

April 27, 2021


It is very difficult to identify each unknown sample which consists of multiple components by using conventional spectrum searching method, because those process is usually very complicated. In order to analyze multi-component sample, first the spectrum of the main component should be searched to find the most similar one from library. And then, the difference spectrum is calculated by subtracting the searched spectrum from the spectrum of the sample, and other components are analyzed through re-searching. It is basically possible to analyze 2nd component in the sample if such method is repeated several times, however searching accuracy declines depending on the number of components in sample.

[Mixture Analysis] which has been added to our standard search engine [KnowItAll] is effective tool for easy analysis of the sample with multiple components. It enables to search spectra for multiple components sample (Max. 4 different components) easily without any data processing such as difference spectrum calculation.

Figure 1. Search result of unknown sample by using of KnowItAll [Mixture Analysis]

This article shows the search result of foreign materials in resin by using [Mixture Analysis].


Measurement conditions
Method : Microscope Transmittance measurement (KBr Plate method)
Resolution : 4 cm-1
Accumulation : 50 times
Aperture size : 100 µm2

Figure 2. Photo of foreign material


The search results by using [Mixture Analysis] are shown in Figure 3 for the foreign material contained in the resin. By these results, unknown sample was identified as calcium carbonate and clay, that is, silicate.

Figure 3. Search of unknown sample by using [Mixture Analysis]

For reference, the results by using conventional [SearchIt] are shown in Figure 4. In this case the spectrum of silicate was searched and then calcium carbonate was identified by calculating the difference spectrum and re-searching.

Figure 4. Result of unknown sample analysis by using [SearchIt]

(Left: Search result of component #1, Right: Result after re-search of difference spectrum))

As explained in the above, for the analysis of sample with multi-components,  [Mixture Analysis] was proved to be a powerful tool.

About the Author

Spectroscopy Group