Abstract:

 A highly sensitive nanoimmunosensor for the determination of ractopamine (RAC) in food samples was
constructed based on a glass carbon electrode modified with carboxylic multi-walled carbon nanotubes/chitosan (MWNTs-
COOH/CS) composite film. Based on the specific immune reaction between antibody and antigen for RAC, the effect
of immune response on immunosensor response current was investigated by cyclic voltammetry and differential pulse
voltammetry using K3[Fe(CN)6] as the probe. The results showed that immune response currents increased linearly with the
cube root of RAC concentration in the range of 0.05–4.05 ng/mL (Ip = − 4.524 4CRAC 1/3 + 14.259, R2 = 0.990 4) with limit
of detection (LOD) of 0.08 ng/mL (RSN = 3). Excellent specificity, stability and reproducibility of the prepared MWNTs-
COOH/CS/RAC-anti immunosensor were observed under the selected conditions. The developed method was applied to the
determination of RAC in pork, beef, mutton, and chicken samples. The results agreed well with those obtained by HPLC
method. Being faster than HPLC method, this immunosensor is practicable for rapid determination of RAC in food samples.

Key words: ractopamine (RAC), nanoimmunosensor, multi-walled carbon nanotubes (MWCNTs), rapid determination, food safety