The Compare tool recently developed for the mass spectra evaluation software package MassLib finds both qualitative and quantitative differences between two GC-MS or LC-MS analyses and presents the results graphically and in tabular form.
The only prerequisite is that the two analyses have been acquired under chromatographically comparable conditions.
For an efficient and successful analyses compare tool several features are required which all are provided in the MassLib software.
A peak finder algorithm must be capable of finding component spectra even if coelutions and variable background is present. It must be possible to compare the two analyses based on retention index scaling and on absolute intensities.
The spectral comparison must reliably recognize that a spectrum is contained in the comparison spectrum even if not readily visible. MassLib's SISCOM algorithm (Search for Identical or Similar COMpounds) is better suited for this task than algorithms that are optimised for determination of spectral identity.
In addition, library searching must be available to identify the components where differences are found. And finally, the comparison must run autonomously and document its results.
Enter 35A or at www.scientistlive.com/elab
MSP KOFEL is based in Zollikofen, Switzerland. www.msp.ch
