Detection of sulphamethazine residues in cattle and pig hair by HPLC–DAD

An HPLC method with diode array detection (DAD) is proposed for the detection of sulphamethazine (SMZ) residues in pig and cattle hair. Hair samples were extracted under alkaline conditions (NH4OH 0.2 M for calf samples and NaOH 0.1 M for piglet samples) and purified with a dual solid-phase extraction (SPE) cartridge system (reverse phase/strong-cation exchange). Recovery of SMZ in fortified samples varied from 70 to 85%, with a limit of quantification of 0.155 ng/mg. Residues of SMZ (7.2–59.2 ng/mg) were detected both in calf and piglet hairs after a therapeutic treatment with SMZ, while no interfering peak was observed in samples from untreated animals.