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Distinguishing between N ‐methylated imidazolinones using mass spectrometry
Author(s) -
Cardaciotto Stanley J.,
Mowery Patrick C.,
Thomson Michael L.,
Wayne Richard S.
Publication year - 1987
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210220607
Subject(s) - chemistry , mass spectrometry , amide , isopropyl , decomposition , nitrogen , spectroscopy , medicinal chemistry , chromatography , organic chemistry , physics , quantum mechanics
Imidazolin‐4‐ones are a new class of herbicides which contain both an amide and amino nitrogen in a five‐membered ring. During the manufacturing process, it is possible to methylate either nitrogen. This presented an interesting analytical problem in distinguishing between the two N ‐methylated derivatives of ASSERT® (a mixture of 6‐(4‐isopropyl‐4‐methyI‐5‐oxo‐2‐imidazolin‐2‐yl)‐ m ‐ and p ‐toluic acid methyl esters) at low levels in a complex mixture. After developing a high‐performance liquid chromatography method for separating and isolating components in the mixture, mass spectrometric techniques, which included electron impact (EI) and collisional activation decomposition (CAD), were used to distinguish between two isomeric N ‐methylated derivatives. The data from the El and CAD experiments enabled amidomethyl and aminomethyl structures to be assigned. Accurate mass measurements and proton nuclear magnetic resonance spectroscopy were used to support the assignments.