RESUMO
A novel derivatization method was developed for the simultaneous determination of six acidic metabolites of catecholamine and serotonin by gas chromatography-mass spectrometry (GC-MS). The metabolites were converted to O-ethoxycarbonyl/tert-butyldimethylsilyl (EOC/TBDMS) derivatives for the direct GC-MS analysis in selected ion monitoring mode. Their mass spectral pattern as EOC/TBDMS derivatives showed characteristic fragment ions of [M - 15](+) and [M - 57](+), which permitted rapid and accurate structural confirmation of acidic metabolites. The present method was linear (r ≥ 0.998), reproducible (percentage relative standard deviation = 1.0-10.0) and accurate (% relative error = -9.7-9.8) with detection limits of 0.001-4.7 ng/mL. When applied to human urine samples, the method allowed simultaneous determination of six acidic metabolites of catecholamine and serotonin.
Assuntos
Catecolaminas/urina , Cromatografia Gasosa-Espectrometria de Massas/métodos , Compostos de Organossilício/química , Serotonina/urina , Adulto , Fenômenos Bioquímicos , Catecolaminas/química , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Modelos Lineares , Masculino , Reprodutibilidade dos Testes , Serotonina/química , SilanosRESUMO
The altered amino acid (AA) levels as neurotransmitter closely correlate to neurodegenerative conditions including Alzheimer's disease (AD). Target profiling analysis of nineteen AAs in brain cortex samples from three Tg2576 mice as AD model and three littermate mice as control model was achieved as their N(O,S)-ethoxycarbonyl/tert-butyldimethylsilyl derivatives by gas chromatography. Subsequently, star pattern recognition analysis was performed on the brain AA levels of AD mice after normalization to the corresponding control median values. As compared to control mice, gamma-aminobutyric acid among ten AAs found in brain samples was significantly reduced (P 0.01) while leucine was significantly elevated (P 0.02) in AD mice. The normalized AA levels of the three AD mice were transformed into distorted star patterns which was different from the decagonal shape of control median. The present method allowed visual discrimination of the three AD mice from the controls based on the ten normalized AA levels.