title: [Determination of L-dopa and dopamine in rat brain microdialysate by ultra high performance liquid chromatography-tandem mass spectrometry using stable isotope-coded derivatization coupled with dispersive liquid-liquid microextraction].
abstract: The sensitive detection method of levodopa (L-DOPA) and dopamine (DA) in rat brain microdialysate of Parkinson's disease (PD) is an essential tool for the clinical study and attenuated synergistic drug screening for L-DOPA from traditional Chinese medicines. Using d0/d3-10-methyl-acridone-2-sulfonyl chloride (d0/d3-MASC) as stable isotope derivatization reagent, a novel ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for L-DOPA and DA by stable isotope- coded derivatization coupled with ultrasonic-assisted dispersive liquid-liquid microextraction (UA-DLLME). d3-MASC (light) and d3-MASC (heavy) were used as derivatization reagents for microdialysate samples and standards, respectively. Mixtures of the two solutions were prepared by UA-DLLME for UHPLC-MS/MS analysis with multiple reaction monitoring (MRM) mode. With d3-MASC heavy derivatives as internal standards for corresponding light derivatives from samples, the stable isotope internal standard quantification for L-DOPA and DA was carried out. The stable derivatives were obtained in aqueous acetonitrile (pH 10.8 sodium carbonate-sodium bicarbonate buffer) at 37 °C for 3.0 min, and then were separated within 2.0 min using gradient elution. Linear range was 0.20-1500.0 nmol/L (R > 0.994). LODs were 0.005 and 0.009 nmol/L for DA and L-DOPA (S/N = 3), respectively. This method was validated, and it showed obvious advantages in comparing with the reported methods in terms of sensitivity, analysis speed and anti-matrix interference. This method has been successfully applied to the study of effect of Shouwu Fang on L-DOPA and DA concentration fluctuations in PD rat brain microdialysate.
authors.forename: Weimei
authors.initials: W
authors.lastname: Qi
authors.forename: Xian-en
authors.initials: XE
authors.lastname: Zhao
authors.forename: Yong
authors.initials: Y
authors.lastname: Qi
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Sun
authors.forename: Guang
authors.initials: G
authors.lastname: Chen
authors.forename: Jinmao
authors.initials: J
authors.lastname: You
authors.forename: Yourui
authors.initials: Y
authors.lastname: Suo
mesh_terms: D000097:Acetonitriles; D000818:Animals; D001921:Brain; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid; D004298:Dopamine / Q000737:chemistry*; D007554:Isotopes; D007980:Levodopa / Q000737:chemistry*; D057230:Limit of Detection; D059627:Liquid Phase Microextraction; D008516:Medicine, Chinese Traditional; D051381:Rats; D053719:Tandem Mass Spectrometry; D014867:Water
chemical_list: D000097:Acetonitriles; D007554:Isotopes; D014867:Water; D007980:Levodopa; D004298:Dopamine; C032159:acetonitrile