This work presents a novel methodology for analysing 5-nitroimidazole residues in milk samples by capillary electrochromatography using lab-made packed columns, produced by carrying out a high pressure packing procedure using acetone as driving solvent and C18 silica uncapped particles (5µm particle size) as packing material. Column frits resulted from sintering the proper stationary phase by heating the packed material for 20s with a nichrome ribbon (80% Ni–20% Cr, 28cm×2mm×0.2mm, electric resistance 1.3Ω) connected to a 7V AC power supply. Lab-made C18 silica packed capillaries (40cmx50µm i.d.) were employed for the determination of 5-nitroimidazole drugs. Milk samples were treated by a salting-out assisted liquid–liquid extraction followed by a solid phase extraction with Oasis®HLB cartridges prior to their injection. Samples were hydrodynamically injected into the column for 120s at 11.5bar. Afterwards eight 5-nitroimidazole compounds were separated in isocratic mode under an applied voltage of 27kV and a temperature of 30°C. The selected mobile phase consisted of a mixture 60:40 acetonitrile:ammonium acetate (2.5mM, pH=5). Separation was monitored at 320nm and it was performed in less than 15min. The method was characterized in terms of linearity (R2≥0.993) and precision (repeatability, RSD≤12.2% and reproducibility, RSD≤14.5%), obtaining detection limits lower than 29µg/L for all compounds under study.