NH2NH-MOF: a reaction matrix for the specific determination of small aldehydes by MALDI-MS.

Efficient determination of aldehydes by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is hampered mainly by the low mass and unstable nature of analytes. In the present work, we propose a combined strategy of a reactive metal-organic framework (MOF) matrix for the derivatization and detection of aldehydes. A novel reactive MOF matrix (NH2NH-MOF) was synthesized in two steps. First, NR3+-MOF was synthesized via Cu2+ and the quaternary amine ligand 4,4'-bipyridinium, 1,1″-(1,2-ethanediyl)bis-, dibromide (PyEtBr). Then, -NHNH2 was introduced to NR3+-MOF through electrostatic adsorption between the -NR3+ and -HSO3- of 4-hydrazinylbenzenesulfonic acid to synthesize NH2NH-MOF. The acid-base chemistry of NH2NH-MOF led to uniform cocrystallization of the aldehyde-matrix mixtures and helped to achieve the detection of low-weight aldehydes with good relative standard deviations (RSDs = 0.07-12.35%). It was confirmed that this strategy can accurately quantify formaldehyde, valeraldehyde, and benzaldehyde with good linearity (r > 0.97). Furthermore, this strategy was applied to quantitatively detect benzaldehyde in wastewater, thus showing potential applications in environmental pollutant detection.