Capillary electrophoresis-electrospray ion-trap mass spectrometry for the separation of chlorophenols

Eighteen positional isomers of chlorophenols were separated by capillary electrophoresis (CE) and detected on-line by electrospray ionization ion-trap mass spectrometry (MS). Conditions for the coupling of CE to MS, e.g., the concentration of carrier electrolyte, the sheath liquid composition and the sheath gas flow-rate were optimized. Diethylmalonic acid (5 mM) at pH 7.25 and isopropanol-250 mM dimethylamine (80:20) as sheath liquid were used. The activation parameters for ion-trap mass spectrometric analysis of chlorophenols were optimized. The mass spectra, obtained for all the analytes, revealed that the [M-H]- ion was the base peak for all chlorophenols. Moreover, conditions for CE-MS-MS detection were established and [M-H-HCl]- ions were detected.