Description of response and charge-state distribution of poly(ether glycol)s in electrospray.
The responses and charge-state distributions of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) (Mn = 400-1000 g/mol) at constant electrolyte concentrations (NaCl, 10(-3) mol/L) in electrospray were studied as a function of the analyte concentration in the concentration range of 10(-2) to 10(-7) mol/L. Single charging occurred in the case of PEG and PPG with Mn = 400 g/mol. It was observed that the response changed nearly linearly with the concentration of the polymer in the low concentration region but above a certain concentration the response leveled off. Saturation of the response at higher concentrations of PEG and PPG of Mn = 1000 g/mol, where double and triple charging occurred, was also observed. Based on the equilibrium partitioning theory a model was developed to account for the response curves and charge-state distributions of singly, doubly and triply charged adduct ions generated from solutions of PEG and PPG. The experimental and the theoretical response curves and charge-state distributions calculated with the model are in fairly good agreement.
Kéki
Sándor
S
Department of Applied Chemistry, University of Debrecen, H-4010 Debrecen, Hungary. keki@tigris.unideb.hu