4-Nitrocatechol as a novel matrix for low-molecular-weight compounds in situ detection and imaging in biological tissues by MALDI-MSI

Low-molecular-weight(LMW)compounds are ubiquitous in living organisms and play essential roles in biological processes.The direct analysis of LMW compounds in biological tissues by matrix-assisted laser desorption/ionization mass spectrometry imaging(MALDI-MSI)could provide a more comprehensive understanding of their essential functions.Here,we evaluated 4-nitrocatechol(4-NC)as a novel positive-ion matrix for enhancing in situ detection and imaging of LMW compounds from the rat liver,brain,and germinating Chinese-yew seed by MALDI-MS.Our results showed that the 4-NC possessed remarkable features,including strong ultraviolet absorption,uniform matrix crystal,excellent chemical stability,and fewer matrix-related background peaks.The use of 4-NC led to the successful detection of 232,218,and193 LMW compounds from the three abovementioned tissue sections,respectively.Also,the use of 4-NC improved the imaging quality of LMW compounds in tissue sections through MALDI-MSI and has the potential as a matrix for MALDI tissue imaging of LMW compounds.