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Quantification of Isolated Methyl Groups in Aquatic Humic Substances by Means of 1H and 13C NMR Spectroscopy

✍ Scribed by J. Lambert; J. Buddrus

Publisher: John Wiley and Sons
Year: 1996
Tongue: English
Weight: 497 KB
Volume: 34
Category: Article
ISSN: 0749-1581
DOI: 10.1002/(sici)1097-458x(199604)34:4<276::aid-omr874>3.0.co;2-2

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✦ Synopsis

To determine the proportion of isolated methyl groups (i.e. methyl groups attached to hydrogen-free carbon) in a ground water humic substance (HS), four different techniques were applied: the standard proton spin-echo technique, the 'H-INADEQUATE method, a short version of the latter with a 4 4 pulse and the proton spin-echo DEPT technique. The standard spin-echo technique proved to be the most suitable. The proportion of isolated paraffinic methyl groups is as high as 60%. Polycyclic isoprenoid structures are considered to be responsible for the occurrence of isolated methyl groups in HS.

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