BACKGROUND: With the aim of developing a highly sensitive immunoassay for carbaryl, a hapten which had high similarity to carbaryl was synthesised using a safer and more practical approach. After it was conjugated to horseradish peroxidase, direct competitive heterologous enzyme-linked immunosorbent assay (CD-ELISA) was optimised and characterised. The assay performance conditions were investigated in details. Enhanced chemiluminescence ELISA (ECL-ELISA) was also used in preliminary studies. RESULTS: The assay obtained an IC(50) value (the concentration causing 50% inhibition) of 2 microg kg(-1), which was 12-fold more sensitive than previous results of homologous CD-ELISA. In ECL-ELISA, the IC(50) was further decreased 10-fold to 0.2 microg kg(-1). The CD-ELISA developed was applicable for broad conditions, and could be applied on various food samples with a more convenient pre-treatment. Average recoveries were in a range of 88.3-101.7%. The results correlated well with those obtained using high-performance liquid chromatography (HPLC) analysis (R(2) = 0.989). CONCLUSION: The ELISA developed was a great improvement in the determination of carbaryl, showing that the immunoassay developed was a simple, rapid and efficient method that was reliable for the detection of carbaryl and suitable for rapid quantitative or qualitative determination in food samples.
BACKGROUND: With the aim of developing a highly sensitive immunoassay for carbaryl, a hapten which had high similarity to carbaryl was synthesised using a safer and more practical approach. After it was conjugated to horseradish peroxidase, direct competitive heterologous enzyme-linked immunosorbent assay (CD-ELISA) was optimised and characterised. The assay performance conditions were investigated in details. Enhanced chemiluminescence ELISA (ECL-ELISA) was also used in preliminary studies. RESULTS: The assay obtained an IC(50) value (the concentration causing 50% inhibition) of 2 microg kg(-1), which was 12-fold more sensitive than previous results of homologous CD-ELISA. In ECL-ELISA, the IC(50) was further decreased 10-fold to 0.2 microg kg(-1). The CD-ELISA developed was applicable for broad conditions, and could be applied on various food samples with a more convenient pre-treatment. Average recoveries were in a range of 88.3-101.7%. The results correlated well with those obtained using high-performance liquid chromatography (HPLC) analysis (R(2) = 0.989). CONCLUSION: The ELISA developed was a great improvement in the determination of carbaryl, showing that the immunoassay developed was a simple, rapid and efficient method that was reliable for the detection of carbaryl and suitable for rapid quantitative or qualitative determination in food samples.