Combining the Katritzky Reaction and Paper Spray Ionization
Mass Spectrometry for Enhanced Detection of Amino Acid Neurotransmitters
in Mouse Brain Sections
posted on 2021-08-31, 19:04authored byLanaia
Ítala Louzeiro Maciel, Ruver Rodrigues Feitosa Ramalho, Raul Izidoro Ribeiro, Mauro Cunha Xavier Pinto, Igor Pereira, Boniek Gontijo Vaz
This work describes
the development of a system that combines a
derivatization protocol based on the Katritzky reaction with paper
spray ionization mass spectrometry (PSI-MS) for the analysis of amino
acid neurotransmitters in mouse brain tissues. The system is relatively
simple, consisting of spraying the derivatization solution onto a
mouse brain section mounted on a glass slide, applying a small volume
of solvent to moisten the sample, pressing a triangular paper onto
the sample surface to transfer the sample constituents to the paper
surface, and using the paper as a substrate for PSI-MS analysis. The
Katritzky reaction facilitated the ionization of the amino acids by
reacting a pyrylium salt with the amino group of the analytes, forming
very stable pyridinium cations, which greatly increased the sensitivity
of the PSI-MS analysis. Most of the intensities of the amino acids
modified by the Katritzky reaction were more than 10 times greater
than the nonderivatized ones. The system was applied for the analysis
of brain sections obtained from mice with Parkinson’s disease,
and the amino acids gamma-aminobutyric acid (GABA) and glycine (Gly),
two compounds very well-known in studies of Parkinson’s disease,
were readily detected. The results suggest that the Katritzky reaction
combined with PSI-MS might offer a significant advance in the knowledge
on protocols that improve the sensitivity of detection of crucial
biological compounds.