Simultaneous determination of β 2 -agonists clenbuterol and salbutamol in water and swine feed samples by dual-labeled time-resolved fluoroimmunoassay

Lanthanide ions, the excellent fluorescence markers, have the potential to simplify the performance of multi-analytes analysis. In this work, a powerful time-resolved fluoroimmunoassay (TRFIA) based on dual-labeled format were performed for detecting clenbuterol and salbutamol simultaneously in water and swine feed samples. Europium (Eu3+)-labeled goat anti-mouse IgG and Samarium (Sm3+)-labeled goat anti-rabbit IgG were prepared and used as fluorescent probes. Under optimal conditions, the half-maximal inhibition concentration (IC50) and the limit of detection (LOD, IC10) of the TRFIA were 0.263 and 0.007 ng/mL for clenbuterol, and 0.179 and 0.014 ng/mL for salbutamol, respectively. The cross-reactivities of the TRFIA between these two β2-agonists and with their analogues were negligible, thus indicated high specificity and promoted the simultaneous determination. The spiked recoveries were 72.2%–102.2% with relative standard deviations (RSDs) of 3.4–13.8% for clenbuterol and salbutamol in water and swine feed samples. Furthermore, the results of TRFIA correlated well with those obtained by HPLC. The proposed dual-labeled TRFIA was a satisfactory tool for simultaneous, sensitive, efficient and labour-saving detection of clenbuterol and salbutamol in water and swine feed samples.