Penicillin analyses by capillary electrochromatography-mass spectrometry with different charged poly(stearyl methacrylate-divinylbenzene) monoliths as stationary phases

► Determination of trace-amounts of penicillin antibiotics by on-line concentration CEC-MS. ► Stationary phases used were two poly(SMA-DVB) monoliths prepared using different polarity charged monomer (VBTA or VBSA). ► The optimized on-line concentration CEC-MS determined penicillin contaminations in milk.