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Evaluation of Fluorinated Indole Derivatives for Electron‐capture Negative Ionization Mass Spectrometry: Application to the Measurement of Endogenous 5‐Methoxyindole‐3‐Acetic Acid in Rat
Author(s) -
Li P.,
Wong K. L.,
Kwan Miranda C. Y.,
Tsang C. W.,
Pang S. F.
Publication year - 1996
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/(sici)1096-9888(199611)31:11<1228::aid-jms411>3.0.co;2-1
Subject(s) - chemistry , yield (engineering) , electron ionization , mass spectrometry , reagent , acetic acid , chemical ionization , mass spectrum , chromatography , ion , ionization , medicinal chemistry , organic chemistry , metallurgy , materials science
A series of N‐trifluoroacetyl/pentafluoropropionyl‐O‐trifluoroethyl/pentafluoropropyl/heptafluorobutyl ester derivatives of 5‐methoxyindole‐3‐acetic acid (5MIAA) were synthesized. Under electron‐capture negative ionization conditions, the N‐trifluoroacetyl derivatives were found to yield relatively abundant, analyte‐specific M ‐• molecular ions and [M−HF] ‐• , [M−HF−CF 2 CO] ‐• and [M−CF 3 CO] ‐ fragment ions, while the N‐pentafluoropropionyl derivatives yielded predominantly the reagent‐specific pentafluoroacylium C 2 F 5 CO ‐ ion. 5‐[ 2 H 3 ]Methoxyindole‐3‐acetic acid was prepared in high yield by a new synthetic procedure and used as the internal standard in subsequent gas chromatographic/mass spectrometric analysis. Using the N‐trifluoroacetyl‐O‐pentafluoropropyl ester derivative, femtomole to low picomole per gland/organ per g ml ‐1 levels of endogenous 5MIAA were identified and determined in the rat pineal gland, retina, whole brain and serum.