Capillary electrochromatography of pyrimidine derivatives using UV and mass spectrometric detection

The separation of pyrimidine derivatives by capillary electrochromatography (CEC) using either UV or mass spectrometric detection is described. For UV detection an aqueous phosphate carrier electrolyte containing acetonitrile is employed. The results are compared to the analysis of the same compound s by micellar electrokinetic chromatography in terms of selectivity, migrat ion times, linearity, and detection limits. For the combination of CEC and mass spectrometry (MS) an inexpensive way to couple commercially available instruments is presented; the interface cons ists of an electrically grounded stainless steel connector (containing a st ainless steel frit) serving as the electrode and coupling the CEC capillary with a fused silica transfer capillary to the MS instrument. Alternatively , a PEEK adapter combining the CEC capillary and a grounded stainless steel transfer capillary serving as the electrode is employed. To avoid the form ation of hydrogen gas at the coupling piece or the transfer capillary, p-be nzoquinone is added to the carrier electrolyte consisting of aqueous ammoni um acetate and acetonitrile.