Using the partial least squares method to model the electrospray ionization response produced by small pharmaceutical molecules in positive mode.

Rationale: The signal intensity in electrospray ionization mass spectrometry (ESI-MS) positive mode is affected by parameters that are related to the physicochemical properties and structural features of a molecule. Accordingly, the combined interactions of an analyte and the mobile phase used is still an area that demands further clarifications since there is no general pattern regarding the nature of a molecule and the mechanism by which vapor-phase ions are produced.

Methods: A multivariate analysis method, such as Partial Least Squares (PLS), provides the opportunity to correlate the effect of a large number of parameters interpreting this complex procedure with the use of appropriate mathematical algorithms.