Diethylation labeling combined with UPLC/MS/MS for simultaneous determination of a panel of monoamine neurotransmitters in rat prefrontal cortex microdialysates.
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 (approximately 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.
Ji
Chengjie
C
Pfizer Global Research & Development, Groton Laboratories, Pfizer Inc., Groton, Connecticut 06340, USA. Chengjie.ji@pfizer.com
Li
Wenlin
W
Ren
Xiao-Dan
XD
El-Kattan
Ayman F
AF
Kozak
Rouba
R
Fountain
Scott
S
Lepsy
Christopher
C
D000586:Amination; D000818:Animals; D015306:Biogenic Monoamines / Q000032:analysis*; D002853:Chromatography, Liquid / Q000191:economics / Q000379:methods*; D004298:Dopamine / Q000032:analysis; D018377:Neurotransmitter Agents / Q000032:analysis*; D009638:Norepinephrine / Q000032:analysis; D009647:Normetanephrine / Q000032:analysis; D010084:Oxidation-Reduction; D017397:Prefrontal Cortex / Q000737:chemistry*; D051381:Rats; D012680:Sensitivity and Specificity; D012701:Serotonin / Q000032:analysis; D053719:Tandem Mass Spectrometry / Q000191:economics / Q000379:methods*; D013997:Time Factors
D015306:Biogenic Monoamines; D018377:Neurotransmitter Agents; D009647:Normetanephrine; D012701:Serotonin; D004298:Dopamine; D009638:Norepinephrine