ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The goal of this study was to establish
a relationship between
the optical properties of soil dissolved organic matter (DOM) and
acidic functions carried out by its individual constituents. We obtained
12 fractions of DOM samples using sequential solid phase extraction
on nonionic sorbent at steadily lowered pH values: 7, 5, 3, 2, which
correspond to low bounds of pK
a values
of phenols, aliphatic, and aromatic carboxylic acids, and ketoacids.
The structural studies were conducted with the use of NMR and selective
deuteromethylation of isolated fractions coupled to ultrahigh resolution
mass spectrometry. First, a gradual shift of molecular compositions
was observed from reduced components to aromatic oxidized compounds
isolated at pH 7 and 2, respectively. Changes in molecular compositions
were accompanied by a red shift of fluorescence spectra. Further application
of deuteromethylation enabled us to distinguish DOM constituents with
different amounts of carboxylic groups. Moreover, identification of
structural isomers in a single DOM sample was achieved. Statistical
analysis revealed that red shift of fluorescence is facilitated by
the increase of a contribution of aromatic poly(carboxylic acid)s
with high conjugation lengths. Additionally, analysis of the labeled
fractionated permafrost thaw DOM directly showed carboxyl-rich alicyclic
molecules, while the same components from lower-latitude DOM were
assigned to lignin-like species.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.