Problem: Researchers have traditionally relied on spectrum search (library search) within their FTIR software or specialized search software for contaminant analysis. Spectrum search can be convenient because it allows in-depth searching of similar contaminant spectra among a great number of spectra in the library. But if the substance is not in the library, a spectra hit list is still displayed, which is very inefficient.
There are additional flaws in the spectrum search system. The spectra in most commercial libraries are obtained from analysis of pure samples of each substance even though contaminants always occur in mixtures. This can cause even a matching spectrum to not be ranked the highest on the hit list. Therefore, it is necessary to conduct an in-depth search in the hit list of spectra that are similar to that of the contaminant. In addition, in situations where there are second and third sub-constituents, researchers must conduct other processes such as generating a difference spectrum just to obtain sufficient information.
Solution: There is a new technique that can make this task more manageable. The technique combines spectrum search and peak matching to identify the principle constituent. More importantly, it indicates the possible existence of sub-constituents from very small characteristic peaks that also appear in the spectrum.
This technique is employed in Shimadzu’s Contaminant Analysis Program (patent pending). The program contains spectra for more than 300 highly selected inorganic substances, organic substances and polymers. These are based on contaminants that are often detected in Shimadzu’s Analytical Applications Department.
This Contaminant Analysis Program isn’t meant to completely replace spectra libraries. However, by compiling a list of common contaminants into one program, it’s now easier for analysts to quickly perform identification checks of anything from raw materials to finished products.
The program incorporates algorithms that focus on spectral characteristics rather than performing simple spectrum searches. It also allows for the automation of the process, including searching, judgment and report creation. Therefore, even analysts with limited experience in infrared spectroscopic analysis will find this is a useful tool in the most difficult aspect of spectral analysis such as identification and qualitative analysis.
The Contaminant Analysis Program interface makes it simple for anyone to use. For example, results for the main constituent and the sub-constituents are displayed in separate fields. The interface uses identifying (+++) marks at the left of the constituent names to indicate the analysis result (a higher number of + marks—maximum 3—indicates the highest possible match). Analysts can compare results of a substance with the contaminant spectra just by clicking on its name in the display field.
Equipped standard with Shimadzu’s IRsolution software, this program provides users with another tool to improve productivity and work efficiency.
For more information, visit http://www.ssi.shimadzu.com
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