A dopamine-imprinted polymer (MIP) was prepared in aqueous methanol solution at 60 o C by free-radical cross-linking polymerization of methacrylic acid in the presence of ethylene glycol dimethacrylate as the cross-linker and dopamine hydrochloride as the template molecule. Its ability to isolate dopamine was evaluated as the basis of a solid phase extraction procedure and compared with that of a non-imprinted polymer (NIP). The binding of dopamine was 84.1% and 29.1% for MIP and NIP, respectively. Various reported post-polymerization treatments to reduce template bleeding were examined. In our case the lowest bleeding was achieved after applying a combined procedure: continuous extraction in a Soxhlet apparatus (CE), followed by microwaveassisted extraction (ME) to a level of 0.061 μg/mL. A simplified model of the templatemonomer complexes allowed rationalization of monomer choice based on the heats of complex formation at a PM3 level of theory.

Higenamine (Norcoclaurine) is a very popular substance in Chinese medicine and is present in many plants. The substance may be also found in supplements or nutrients, consumption of which may result in violation of anti-doping rules. Higenamine is prohibited in sport at all times and included in Class S3 (β-2-agonists) of the World Anti-Doping Agency (WADA) 2017 Prohibited List. The presence of higenamine in urine samples at concentrations greater than or equal to 10 ng/mL constitutes an adverse analytical finding (AAF). This work presents a new metabolite of higenamine in urine sample which was identified by means of ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Samples were prepared according to 2 protocols - a Dilute and Shoot (DaS) approach and a method involving acid hydrolysis and double liquid-liquid extraction (LLE). To meet the requirements typical for a confirmatory analysis, the screening procedure was further developed. In samples prepared by the DaS method, 2 peaks were observed; the earlier one was specific for higenamine and the later one unknown. MS scan analysis showed mass about 80 Da higher than that of higenamine. In turn, in samples prepared in accordance with the protocol involving hydrolysis, an increase in the area under peak for higenamine was observed, while the second peak was absent. It seems that the described strategy of detection of higenamine in urine avoids false negative results.

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An efficient molecularly imprinted solid-phase extraction protocol was developed for the separation of dopamine (DA) from human urine. After successful validation of the analytical method using high-performance liquid chromatography coupled with fluorescence detection, a new strategy for the selective determination of DA in the presence of norepinephrine and epinephrine in human urine was presented. In the proposed protocol, the LODs and quantification for DA were 166 ± 36 and 500 ± 110 nmol/L, respectively, and the total recoveries of DA in the range of 1-15 μmol/L varied between 98.3 and 101.1%. DA was detected in the real urine samples at the level of 47-167 μg/L (0.250-0.895 μmol/L). The superiority of the novel analytical strategy was shown by comparison with the results obtained for a commercially available imprinted sorbent.