Development of a direct competitive enzyme-linked immunoassay for carbofuran in vegetables

Three ELISA formats, antigen coated, antibody coated and the second antibody coated for the determination of carbofuran were investigated with conjugations including hapten–BSA, hapten–OVA, hapten–HRP and anticarbofuran IgG–HRP. Results showed that the second antibody-coated method of ELISA had a better performance in the establishment of standard curves and detection of carbofuran residue in vegetables samples. The sensitivity for detection, the I₅₀ value was 36.1 ng/ml at a practical working concentration range from 3.44 to 380.1 ng/ml and the limit of detection for carbofuran was 3.44 ng/ml. The average recoveries of determination for carbofuran spiked in cabbage, lettuce, carrot, winter fragrant-flowered garlic, bamboo shoot and green soy bean were 85.24%, 101.8%, 103.6%, 90.52%, 106.9% and 94.08%, respectively. Additional analyses confirmed that the results given by the ELISA method was in agreement with those of the gas chromatography (GC) method.