Structural analysis of alfa grass (Stipa tenacissima L.) lignin obtained by acetic acid/formic acid delignification.

Alfa grass lignin obtained by the acetic acid/formic acid/water CIMV pulping process was characterized by FTIR and (1)H, (13)C-(1)H 2D HSQC, and (31)P NMR spectroscopies. Lignin samples purified by further dissolution/precipitation or basic hydrolysis steps were also analyzed. The CIMV alfa lignin is a mixture of low molar mass compounds (M(n) = 1500 g/mol) of SGH type with β-O-4 ether bonds as the major interunit linkage.

Gas-phase fragmentation study of a novel series of synthetic 2-oxo-2H-benzopyrano[2,3-d]pyrimidine derivatives using electrospray ionization tandem mass spectroscopy measured with a quadrupole orthogonal time-of-flight hybrid instrument.

The fragmentation patterns of a series of six novel synthesized benzopyranopyrimidine derivatives 1-6, possessing the same 2-oxo-2H-benzopyrano[2,3-d]pyrimidine backbone structure, were investigated by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS) techniques using a quadrupole orthogonal time-of-flight (QqToF)-hybrid instrument. The series of six pure benzopyranopyrimidine compounds contained three constitutional isobaric isomers (compounds 4-6). A simple methodology, based on the use of ESI (positive ion mode) and increasing the declustering potential in the atmospheric pressure/vacuum interface resulting in collision-induced dissociation (CID), was used to enhance the formation of the product ions.