*2.3. Preparation of mAb*

The preparation of mAb was performed according to that described in our laboratory by Peng et al. [17]. Briefly, sixteen female Balb/C mice were randomly divided into four groups for culture. Two immunogens (MQCA–PABA–BSA and DMEQ–AOAA–HSA) were immunized at a dose of 50 and 100 μg each. Then, serum titers and specificity were monitored by conventional ELISA procedures using MQCA–PABA–OVA and DMEQ– AOAA–OVA as homologous and heterologous coating antigens, respectively [18]. The mice with the best titer and specificity were selected to obtain splenocytes in vitro and fused with mouse myeloma cells. Under screening by the ELISA method, positive monoclonal cell lines were obtained after subcloning the fused cells using the limited dilution method 3–5 times. Finally, mAb was prepared by ascites induction, purified using protein A affinity chromatography, and stored at −20 ◦C until use.
