Synthesis and characterization of hapten-quantum dots bioconjugates: Application to development of a melamine fluorescentimmunoassay

► Novel characterization of hapten-BSA conjugates by optical and mass spectrometry. ► QD-based competitive immunoassay for melamine in infant formula milk. ► Direct analysis of melamine without any sample pretreatment. ► Detection limit one order of magnitude lower than the established by legislation.