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
QI Weimei1, ZHAO Xian-en2, QI Yong1, SUN Zhiwei2, CHEN Guang2, YOU Jinmao2,3, SUO Yourui3
1. Chemical Department, Laiwu Vocational and Technical College, Laiwu 271100, China;
2. Shandong Provincial Key Laboratory of Life-organic Analysis, Key Laboratory of Pharmaceutical Intermediates and Analysis of Natural Medicine, College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, China;
3. Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China
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). d0-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 ℃ 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.
QI Weimei,ZHAO Xian-en,QI Yong et al. 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[J]. Chinese Journal of Chromatography, 2015, 33(9): 981-987.