posted on 2014-11-18, 00:00authored byDébora Tomasini, Francesco Cacciola, Francesca Rigano, Danilo Sciarrone, Paola Donato, Marco Beccaria, Elina B. Caramão, Paola Dugo, Luigi Mondello
In this work, two analytical liquid
chromatography methods were developed and compared for the characterization
of aqueous phases from pyrolysis of lignocellulosic biomasses. NanoLC
electron ionization-mass spectrometry (EI-MS) represents a novel and
useful tool for both separation and identification of semi/nonvolatile
and thermolabile molecules. The use of nanoscale flow rates, the highly
reproducibility, and high detailed information on EI spectra are the
principal advantages of this technique. On the other hand, comprehensive
2D-LC, providing a two-dimensional separation, increases the overall
peak capacity lowering the occurrence of peak coelutions. Despite
the use of reversed phase modes in both dimensions, a satisfactory
degree of orthogonality was achieved by the employment of a smart
design of gradient elution strategies in the second dimension in combination
with photodiode array detection (PDA) and atmospheric pressure chemical
ionization-mass spectrometry (APCI-MS). Because of the absence of
the preliminary extraction procedure, the fingerprint obtained for
these samples results is independent of the extraction yield or contamination
contrary to the gas chromatography-mass spectrometry (GC-MS) approach
where a liquid–liquid extraction of the water phase is necessary.
The main classes of identified compounds were phenols, ketones, furans,
and alcohols. The synergistic information on the two powerful analytical
approaches, e.g., NanoLC EI-MS and LC × LC, in the identification
of such complex samples has never been investigated and fully benefit
on the one hand from the superior degree of mass spectral information
from EI-MS and on the other hand from enhanced LC × LC compound
separation.