Diethylation Labeling Combined with UPLC/MS/MS for Simultaneous Determination of a Panel of Monoamine Neurotransmitters in Rat Prefrontal Cortex Microdialysates

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• 作者：Chengjie Ji ; Wenlin Li ; Xiao-dan Ren ; Ayman F. El-Kattan ; Rouba Kozak ; Scott Fountain ; Christopher Lepsy
• 刊名：Analytical Chemistry
• 出版年：2008
• 出版时间：December 1, 2008
• 年：2008
• 卷：80
• 期：23
• 页码：9195-9203
• 全文大小：239K
• 年卷期：v.80,no.23(December 1, 2008)
• ISSN：1520-6882

文摘

The primary challenge associated with the development of an LC/MS/MS-based assay for simultaneous determination of biogenic monoamine neurotransmitters such as norepinephrine (NE), dopamine (DA), serotonin (5-HT), and normetanephrine (NM) in rat brain microdialysates is to improve detection sensitivity. In this work, a UPLC/MS/MS-based method combined with a diethyl labeling technique was developed for simultaneous determination of a panel of monoamines in rat prefrontal cortex microdialysates. The chromatographic run time is 3.5 min/sample. The limits of detection of the UPLC/MS/MS-based method for NE, DA, 5-HT/ and NM, with/without diethyl labeling of monoamines, are 0.005/0.4 (30/2367 pM), 0.005/0.1 (33/653 pM), 0.005/0.2 (28/1136 pM), and 0.002/0.2 ng/mL (11/1092 pM), respectively. Diethyl labeling of amino groups of monoamines affords 20−100 times increased detection sensitivity of corresponding native monoamines during the UPLC/MS/MS analysis. This could result from the following: (1) improved fragmentation patterns; (2) increased hydrophobicity and concomitantly increased ionization efficiency in ESI MS and MS/MS analysis; (3) reduced matrix interference. This labeling reaction employs a commercially available reagent, acetaldehyde-d₄, to label the amine groups on the monoamines via reductive amination. It is also simple, fast (25-min reaction time), specific, and quantitative under mild reaction conditions. Data are also presented from the application of this assay to monitor the drug-induced changes of monoamine concentrations in rat prefrontal cortex microdialysate samples followed by administration of SKF 81297, a selective D₁ dopamine receptor agonist known to elevate the extracellular level of the neurotransmitters DA and NE in the central nervous system.