Preparation of a stir bar coated with molecularly imprinted polymer and its application in analysis of dopamine in urine

• A simple method to prepare MIP-SB for dopamine extraction was introduced.
• The MIP-SB was used to separate and enrich trace dopamine in human urine samples for the first time.
• No elimination of protein or organic solvent is needed when using the MIP-SB to prepare urine samples.

A molecularly imprinted polymer coated stir bar (MIP-SB) using dopamine as a template was fabricated. The adsorptive capacity of the MIP-SB was almost 4 times over that of non-imprinted stir bar. The MIP-SB showed good extracting selectivity for dopamine when used to adsorb dopamine and its analogs. An analytical method to determine dopamine in urine sample was established by combining MIP-SB sorptive extraction with HPLC-fluorescence detector. The linear range of dopamine concentration was 0.378–18.9 ng/ml with correlation coefficient of 0.9990, and the limit of quantification was about 0.0945 ng/ml (S/N = 10). The recoveries of dopamine with spiked urine samples at three different levels were between 92.3 and 106.9%, and the relative standard deviations were within 13.2% (n = 3). The method is simple and suitable for the determination of dopamine in human urine for clinical application.

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