“…The residue was dissolved with ethyl acetate (30 mL) and then was washed 3 times with hydrochloric acid (0.1 M, 40 mL) followed by purified water (30 mL) for 2 times. The solvent was The haptens were coupled to BSA or HSA by the active eater method (Xu et al, 2005;Luo et al, 2009a) to prepare 4 immunogens (FF-SH-BSA, FF-SH-HSA, FF-MH-BSA, and FF-MH-HSA). Briefly, the hapten (50 mg, 0.11 mmol) dissolved in A^,A'^dimethylformamide (4 mL) was mixed with A''-hydroxysuccinamide (27 mg, 0.23 mmol) and Af,A''-dicyclohexylcarbodiimide (49 mg, 0.24 mmol).…”