| Summary: | In 2004, octopamine was added to the list of drugs banned by the world anti-doping agency (WADA) and prohibited in any sport competition. This work aims to develop a new analytical method to detect octopamine in water and human urine samples. We proposed a pseudo-enzyme-linked immunosorbent assay (pseudo-ELISA) by replacing traditional monoclonal antibodies with molecularly imprinted polymer nanoparticles (nanoMIPs). NanoMIPs were synthesised by a solid-phase approach using a persulfate initiated polymerisation in water. Their performance was analysed in pseudo competitive ELISA based on the competition between free octopamine and octopamine-HRP conjugated. The final assay was able to detect octopamine in water within the range 1 nmol·L<sup>−1</sup>−0.1 mol·L<sup>−1</sup> with a detection limit of 0.047 ± 0.00231 µg·mL<sup>−1</sup> and in human urine samples within the range 1 nmol·L<sup>−1</sup>−0.0001 mol·L<sup>−1</sup> with a detection limit of 0.059 ± 0.00281 µg·mL<sup>−1</sup>. In all experiments, nanoMIPs presented high affinity to the target molecules and almost no cross-reactivity with analogues of octopamine such as pseudophedrine or <span style="font-variant: small-caps;">l</span>-Tyrosine. Only slight interference was observed from the human urine matrix. The high affinity and specificity of nanoMIPs and no need to maintain a cold chain logistics makes the nanoMIPs a competitive alternative to antibodies. Furthermore, this work is the first attempt to use nanoMIPs in pseudo-ELISA assays to detect octopamine.
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