Study On The Analysis Of Monoamine Neurotransmitters In Urine Based On The Separation And Enrichment With Functionalized Magnetic Nanoparticles

Monoamine neurotransmitters, including norepinephrine(NE), epinephrine(E), dopamine(DA) and 5-hydroxytryptamine(5-HT), which play an very important role in the body. The monoamine neurotransmitters were directly involved in many physiological activities. The concentration of monoamine neurotransmitters in the body was closely associated with many human diseases. Therefore, studying on the changes of the monoamine neurotransmitters content of the body has great important significance. Human urine has become the preferred biological fluid samples because of its advantages of easy acquisition, large amount and sampling painless. The human urine has complex matrix, and the level of the monoamine neurotransmitters is very low. Therefore, it is often unable to detect the analytes directly. As a consequence, it is necessary to develop an effective sample preparation method for the sample separation and enrichment, and then detect by the instrument. In recent years, magnetic solid phase extraction has been widely used in complex substrate pretreatment because the magnetic solid phase extraction has an advantage of simple operation, easy separation, safety and so on.This paper aims to develop functionalized magnetic nanoparticles to separate and enrich the monoamine neurotransmitters in human urine. In this study, three types of functionalized magnetic nanoparticles were prepared and characterized by a variety of characterization methods. The monoamine neurotransmitters were analyzed with separation and enrichment of the as-synthesized magnetic particles in urine coupled with high performance liquid chromatography with electrochemical(HPLC-ECD) or mass spectrometry(MS). Several high sensitivity analysis methods were established to analyze the monoamine neurotransmitters in urine.The main contents are as follows:1. The overview of physiological effect, detection methods and pretreatment methods of the monoamine neurotransmitters. In addition, the preparation of the functionalized magnetic nanoparticles was further expounded.2. SnO2 modified magnetic nanoparticles(Fe3O4@mSiO2@nSnO2 NPs) was synthesized and characterized by Fourier transform infrared spectrometer(FT-IR), X-ray diffractometer(XRD), vibrating sample magnetometer(VSM), scanning electron microscope(SEM) and dynamic light scattering(DLS). NE, E, DA and 5-HT were separated and enriched by the prepared Fe3O4@mSiO2@nSnO2 NPs, and then detected by high performance liquid chromatography-electrochemical detection(HPLC-ECD). The high sensitivity analysis method was established to separate and analyze the monoamine neurotransmitters in urine. The Fe3O4@mSi O2@n SnO2 NPs showed strong adsorption capacity for NE, E and DA, but a bit poor for 5-HT. It is demonstrated that the as-synthesized magnetic particles have good selectivity for the compounds containing ortho phenolic hydroxyl groups. The established method showed a good linearity with R between 0.9975 and 0.9993 while the linear ranges were 0.01~5 μg/mL, the limit of detection of NE, E and DA were 6.7, 5.8, 7.3 ng/mL respectively. The relative standard deviations were less than 8 %. The extraction recoveries in urine samples ranged from 91 % to 105 %. The method was proved to be accuracy and sensitivity.3. La2O3 modified magnetic nanoparticles(Fe3O4@mSiO2@nLa2O3 NPs) was synthesized and characterized by FT-IR, XRD, VSM, SEM and DLS. NE, E and DA were separated and enriched by the prepared Fe3O4@mSi O2@n La2O3 NPs, and then detected by ambient mass spectrometry. The Fe3O4@mSiO2@nLa2O3 NPs-MS separation and analysis method of urine catecholamine neurotransmitters was established. Parameters that influence the extraction efficiency, including pH of sample solution, time for adsorption and desorption, concentrations of desorption solvent were investigated. The results showed that the Fe3O4@mSi O2@n La2O3 NPs exhibited good extraction efficiency on NE, E and DA. The results showed a good linearity with R between 0.9926 and 0.9959 while the linear ranges were 0.01~1 μg/mL, the limit of detection of NE, E and DA were 4.5 ng/mL, 5.3 ng/mL and 6.8 ng/mL, respectively. The relative standard deviations were less than 20 %. The extraction recoveries in urine samples ranged from 85 % to 105 %. The established method was proved to be simple, rapid, sensitive and accurate.4. Nb2O5 modified magnetic nanoparticles(Fe3O4@mSiO2@n Nb2O5 NPs) was prepared and characterized by FT-IR, XRD, VSM and DLS. NE, E and DA were separated and enriched by the prepared Fe3O4@mSi O2@n Nb2O5 NPs, and then detected by ambient mass spectrometry. The Fe3O4@mSi O2@nNb2O5 NPs-MS separation and analysis method of urine catecholamine neurotransmitters was established. Parameters that influence the extraction efficiency, including pH of sample solution, time for adsorption and desorption, concentrations of desorption solvent were investigated. The results showed a good linearity with R between 0.9908 and 0.9924 while the linear ranges were 0.01~1 μg/mL, the limit of detection of NE, E and DA were 3.4 ng/mL, 8.2 ng/mL, 7.5 ng/mL, respectively. The relative standard deviations were less than 20 %. The extraction recoveries in urine samples ranged from 85 % to 105 %. The method was proved to be simple, rapid and sensitive.