Peak® Spectroscopy implements the most important techniques in Quant, developed in collaboration with some of the world's most expert practitioners of Chemometrics. These field-tested tools are used world-wide in critical enviromental, forensic, industrial and military applications.
PLS is a very versatile technique used for liquid, solid and vapor phase samples.
An advantage of PLS is that the method does not have to know about all possible constituents in a mixture. The standards used in the model need to incorporate the range of possible samples found in the field, but does not require spectra of pure compounds, as needed in CLS. Another advantage is that the full spectrum can often be used, it is not always necessary to indentify analysis regions for each compound in the PLS model.
CLS is often used for the analysis of complex mixtures of gases (vapor phase samples), for instance combustion processes.
CLS requires spectra of pure compounds of known concentrations, known as a 'standard' or 'calibration' spectrum. In some cases you may need only one standard for a given compound, if the concentration vs. absorbance curve is linear. Often, however, the absorbance will fall off at higher concentrations, so the calibration curve is not linear. In this case, for a more accurate measurement, it is necessary to provide more calibration spectra at a range of concentrations.
Peak® Spectroscopy Software's CLS implementation is based on the 'multi-band weighting' technique combined with standard-bracketed interpolation, providing robust and sensitive concentration measurements.
Click this link for more information about Library Search and Spectral Libraries: librarySearch.html
QC Compare is often used to test incoming materials. It answers the simple question: "Is this or is this not the material it is supposed to be?".
Conformity Index is like QC Compare but is more sensitive. It is often used with NIR spectra. More information is on the Conformity Index page.