Liquid Chromatograph Mass Spectrometer
Formula Predictor (Optional Product)
Effectiveness of Accurate MSn
In composition prediction, target constituents having a small mass and high mass accuracy associated with their measured values, provide fewer numbers of candidates and greater prediction reliability. When using information-rich MSn data with the Formula Predictor software, formula predictions starts with the product ion having the smallest mass, and uses that result in the effective prediction of the parent ion by reducing the number of candidates.
Take, for example, the case of predicting the elemental composition of the ion at m/z 371.1645. The correct composition is C17H26N2O5S+H+ (m/z 371.1641).
The composition prediction procedure is as follows:
In this way, using the isotopic patterns enables the correct formula to achieve a higher ranking. Furthermore, using MSn data enables a reduction in the number of candidates.