R
Isomer is a program developed by our lab to assist with calculation of R-isomer scores.
1 M/z values and intensities for two different spectra are copied into the clipboard and then pasted into "Spectrum A" and "Spectrum B" via the "PasteA/B" buttons. The mass tolerance is able to be adjusted to reflect the resolution of the data being analyzed. The "Calculate Masslist" button produces the mass list. Peaks appearing in one spectra but not the other deserve extra scrutiny. If they appear to represent a coelution or unexplained peak, they should be added to the mass elimination list, and then the mass list can be cleared and re-calculated. The “Peak Threshold” indicates the relative intensity that should be observed in at least one of the spectra, typically set a 5%. Generally, if both peaks are very low intensity, changes in abundance are not meaningful. After obtaining a mass list in which all m/z's are paired and the appropriate threshold has been set, clicking the button "Calculate R" then calculates the R-isomer score based on a ratio of ratios of intensities of two peaks occuring in both fragmentation spectra. The highest values will be listed first.