Direct monitoring of chemical transformations by combining thin layer chromatography with nanoparticle-assisted laser desorption/ionization mass spectrometry

Abstract

A nanomaterial-assisted method that combines thin layer chromatography (TLC) with matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) was developed to directly monitor chemical transformations. A substrate-dependent extraction strategy was studied and successfully used to identify target molecules from the depths of a developed TLC plate. By using this strategy, a hydrophobic sample of interest was enriched on the surface of the TLC plate in the presence of acetonitrile, in contrast to using water and methanol to identify hydrophilic samples. The successful enrichment of samples by specific solvents provided stable desorption/ionization efficiencies of compounds of interest and led to very good sensitivity near the attomole scale. The method was then used to monitor 4-dimethylaminopyridine (DMAP)-catalyzed acylation in preparation of bifunctional sulfonamides. The labile DMAP-acyl intermediate and final sulfonamide product were clearly identified on TLC plates without external purification or sample preparation. Furthermore, in combination with collision-induced dissociation (CID) to provide structural information, the technique was successfully used in the natural product discovery of anti-inflammatory flavonoids from Helminthostachys zeylanica, a traditional Chinese herb. The newly proposed method provides a very low background from silica supports or organic matrices in the low molecular weight range (100-1000 Da). The technique may greatly accelerate studies of metabolomics, drug discovery, and organic synthesis.

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2013–2014

“…Polydimethylsiloxane‐coated stainless steel plates have been used to enhance the signal intensity of peptides, phosphopeptides, and carbohydrates without producing any increase in background signals. With DHB, the signals from carbohydrates were about three times more intense than with uncoated plates and more abundant ions were produced in MS/MS experiments (Chen et al, ).…”

“…DHB has been covalently conjugated onto the surface of iron oxide magnetic nanoparticles (MNPs) to improve performance of the matrix when used in conjunction with thin‐layer chromatographic (TLC) separation of small molecules, including carbohydrates and to monitor chemical transformations (Chen et al, ). After development of the TLC plates, the matrix was added to the surface and the plate was attached to the MALDI target with conductive adhesive tape.…”

Laser desorption-ion mobility spectrometry as a useful tool for imaging of thin layer chromatography surface

“…Mass spectrometry (MS) with different ionization sources is a powerful technique for detection and characterization of vast spectrum of chemical compounds. In TLC, the analyte is deposited on the plate, therefore, the analyte should be sampled from the TLC surface and gasified in order to be detected by MS. Coupling of TLC with MS has been carried out using different techniques and ionization sources such as laser desorption ionization (LDI) [6][7][8][9] secondary ion mass spectrometry (SIMS) [10] matrix-assisted laser desorption ionization (MALDI) [11][12][13][14][15] surface-assisted laser desorption ionization (SALDI) [16,17] electrospray ionization (EI) [18][19][20][21] electrospray laser desorption ionization (ELDI) [22,23] laser-induced acoustic desorption electrospray ionization (LIAD/ESI) [24] laser desorption/inductively coupled plasma (LD/ICP) [25,26] and so on. Also, different mass spectrometers including time of flight (TOF) ion trap and quadruple are used to detect and analyze the analytes sampled from the TLC surface.…”

Application of flowerlike MgO for highly sensitive determination of lead via matrix‐assisted laser desorption/ionization mass spectrometry

“…Nanomaterials have been applied in LDI‐MS‐based analysis to provide a promising approach to achieve high sensitivity and selectivity towards specific analytes due to their unique physical and chemical properties . They can largely absorb laser energy and transfer the energy to target molecules to facilitate their desorption and ionization .…”