Preparation of poly (methacrylic acid)/graphene oxide aerogel as solid-phase extraction adsorbent for extraction and determination of dopamine and tyrosine in urine of patients with depression

Dopamine (DA) and l-tyrosine (l-Tyr) are neurotransmitters involved in various neuropsychiatric disorders. Therefore, it is important to monitor their levels for diagnosis and treatment. In this study, we synthesized poly (methacrylic acid)/graphene oxide aerogels (p(MAA)/GOA) by in situ polymerization and freeze-drying using graphene oxide and methacrylic acid as substrates. Then, the p(MAA)/GOA were applied as solid-phase extraction adsorbents to extract DA and l-Tyr from urine samples, followed by quantification using high performance liquid chromatography (HPLC). The p(MAA)/GOA showed better adsorption performance for DA and l-Tyr than commercial adsorbents, likely as a result of the strong adsorption of the target analytes via π-π and hydrogen bonding interactions. Further, the developed method had good linearity (r > 0.9990) at concentrations of DA and l-Tyr of 0.075-2.0 and 0.75-20.0 μg mL-1, respectively, as well as a limit of detection of 0.018-0.048 μg mL-1, limit of quantitation of 0.059-0.161 μg mL-1, spiked recovery of 91.1-104.0%, and interday precision of 3.58-7.30%.The method was successfully applied to determine DA and l-Tyr in the urine samples of patients suffering from depression, demonstrating its potential for clinical applications.