Separation of N-2-ethyl-2 '-deoxyguanosine-5 '-monophosphate and four native deoxyribonucleoside monophosphates using capillary zone electrophoresis with polyethylene glycol as buffer additive

We investigated the separation of five deoxyribonucleoside monophosphates: 2'-deoxyguanosine-5'-monophosphate (dGMP), 2'-deoxyadenosine-5'-monophospha te (dAMP), 2'-deoxycytosine-5'-monophosphate (dCMP), 2'-deoxythymidine-5'-m onophosphate (dTMP) and a dGMP adduct possessing N-2-ethyl-guanine, which h as been noted in relation to mutagenesis of alcohol, using capillary zone e lectrophoresis (CZE). The concentration of polyethylene glycol (PEG) as a m odifier and the pH of the running solutions can efficiently control the obs erved separation. Interaction of PEG with analytes was quantitatively evalu ated. PEG worked effectively as a hydrophobic selector in these separations . The values of pK(a) of the acidic-NH-groups in the base moieties of dGMP, dTMP, and the dGMP adduct are close to that of boric acid used as buffer o f the running solutions. The control of their charge was facilitated, enabl ing improved separations. A more sufficient and fast separation was achieve d by both optimization of pH of the running solutions and PEG concentration compared with that obtained by pH control alone. On-line concentration usi ng a stacking method followed by the PEG-assisted CZE was briefly studied.