Development of a capillary electrophoresis-based immunoassay with laser-induced fluorescence for the detection of carbaryl in rice samples.

A capillary electrophoresis-based competitive immunoassay (CEIA) with a laser-induced fluorescence (LIF) detector for the determination of carbaryl was developed. The method was based on the competitive reactions between fluorescently labeled carbaryl tracer (Ag*) and free carbaryl (Ag) with a limited amount of anticarbaryl antibody (Ab), and the relative amounts of each were separated and determined by capillary electrophoresis (CE) with an LIF detector. Using CEIA, equilibrium was reached in 30 min, and the analytical results were obtained within a further 8 min. The linear range and the detection limit for carbaryl were 0.16-50 ng/mL and 0.05 ng/mL, respectively. The sensitivity of this CEIA with an LIF detector was almost 14 times greater than that of ELISA, which used the same immuno-reagents. The method was also applied to the analysis of carbaryl in rice with rapid and simple sample pretreatment. The method is thus proposed as a fast and sensitive assay for the detection of carbaryl.