FIA-EQCN biosensor for analysis of sulphadiazine residues in milk

The widespread use of antibiotics within the farming industry is one of the factors that have been linked to the appearance of these residues in milk. A flow injection analysis-electrochemical quartz crystal nano-balance (FIA-EQCN) biosensor is presented for label free analysis of sulphadiazine residues in milk. The biosensor constituted a polyclonal antibody of sulphadiazine covalently immobilized to a gold coated quartz crystal mounted on a flow cell attached with FIA-EQCN setup. The biosensor showed linearity in the range 50 to 200 μg kg ^-1, with minimum detection limit of 10 μg kg^-1, R² 0.97 and ^% R.S.D. 0.83. Good recoveries were obtained (98.6-100.5^%) for sulphadiazine in the spiked milk samples. A good correlation was observed between the sulphadiazine concentrations measured through FIA-EQCN and the commercial ELISA kit. These results indicate that utilizing this system could be very effective to detect low level of sulphadiazine residues in milk.