Effect of mobile phase additives on linearity in particle beam lc/ms

Although Particle Beam Liquid Chromatography/Mass Spectrometry (PB LC/MS) has been shown to be useful for the identification and confirmation of nonvolatile and thermally labile compounds, evidence has been reported of response nonlinearity at low concentrations. Addition of a mobile phase additive to the HPLC mobile phase improves the linearity via a so-called "carrier effect.”

A study has been done to characterize the physical and chemical phenomena involved in this carrier effect. A matrix of probes and additives were combined at 9 levels (2-1000ng) while Single Ion Monitoring (SIM) monitored the effectiveness of each additive on linearity and sensitivity. Next, the pH and concentration of the additive were varied for the 24 sample probes, ranging from pharmaceutical to environmental samples. Data is provided demonstrating the statistical effect on quantitative performance for each study. Analytical examples are shown.

A mathematical model has been applied to account for the nonlinearity of PB LC/MS. For a given droplet distribution, reducing the concentration of the analyte results in reduced particle size. Application of a high pass filter to a particle distribution replicates response factor and signal obtained by PB LC/MS. In addition, a mathematical model representing the linear response upon addition of a nonvolatile buffer has been successfully applied. Graphs are presented showing the feasibility of this model.