In previous studies we have shown that highly reproducible peptide MALDI ion signals proportionate to deposited surface concentration are achieved via an approach wherein ion signal resolution is held constant (as opposed to desorption laser intensity).  The observed improvements in ion signal RSD are believed to be a result of greater reproducibility being achieved in the amount of analyte desorbed and ionized.  In the current study, we investigate the effect of applying this quantification approach to individual peptides contained within simple to complex mixtures.  The goal of the studies is to determine if changes in peptide properties and/or competitive ionization impacts ion signal RSDs under constant resolution conditions.  1mg/ml stock solutions of AngIII, Bradykinin, Pkg and Buccalin in ACN/water/0.1%TFA were prepared. Subsequently, 1:1 mixtures were prepared of all possible combinations of peptides. Similar procedures were followed for the tryptic digest peptides of BSA MALDI mass spectra were obtained in the positive ion mode using a Bruker Microflex MALDI mass spectrometer.  In the studies performed A MALDI mass spectrum having a good S/N ratio is first collected for a given peptide. The resolution of this ion signal is then used as the reference for the other MALDI mass spectra collected. Specifically, the desorption laser intensity is adjusted individually to produce ion signals having near identical base widths as those for the reference mass spectrum. Using this approach we have observed an average RSD of 10.3% and R2 value of 0.9665 for AngI(m/z 1296) by itself. This is a huge improvement when compared to the conventional average RSD of 39.4% and R2 value of 0.2246.

Effects of peptide properties on quantification by MALDI MS

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.