A novel and label free electrochemical immunosensor for salbutamol(SAL) detection was developed with alizarin (AR) as a redox probe,and titanium dioxide hybridized acetylene black and chitosan composites (TiO2-AB-CS) as a signal amplification platform.Au NPs were electro deposited on the modified electrode surface to immobilize the SAL antibody(anti SAL),which could further enhance the current response.Scanning electron microscope(SEM) was used to characterize the materials.Cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) were used to characterize the construction process of modified electrode and the electrochemical properties of the immunosensor.Differential pulse voltammetry(DPV) was used to detect the peak current of alizarin on the surface of modified electrode,the peak current of the proposed immunosensor decreased linearly with the increase of SAL concentration when the immune-reaction was carried out with anti-SAL,and the relationship between the peak current and SAL concentration was established to accomplish the quantitative detection on SAL.The experimental factors affecting current response were explored,including pH of phosphate buffer solution (PBS),incubation temperature and incubation time.Under the optimized conditions,the linear range of the immunosensor was obtained to be 1.0-100 μg/L with a limit of detection(LOD) of 0.67 μg/L(3σ/k).With the advantages of good reproducibility,specificity and stability,the immunosensor was successfully applied in the detection of SAL in swine feed and pork samples with satisfactory results.The recoveries of SAL in swine feed and pork were in the ranges of 100.2%-102.4% and 97.5%-103.3% with relative standard deviations(RSDs) of 1.9%-4.7% and 2.1%-3.5%,respectively.