Detection of Long Alkyl Esters of Succinic and Maleic Acid Using TLC-MALDI-MS

Abstract

Four esters of succinic and maleic acid were synthesized, separated by thin-layer chromatography (TLC), and identified using matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). A comparison of matrix materials showed that 2,6-dihydroxybenzoic acid (2,6-DHB) yielded a greater ionization efficiency than 2,5-DHB prior to TLC separation. The location of each ester sample on the TLC plate was estimated by comparing the developed plate with a duplicate plate that had been visualized by immersion in a KMnO4 solution. Generally, mass spectra obtained from the KMnO4-visualized plate were relatively poor. Reproducible mass spectra with high peak abundance were difficult to obtain using the 2,6-DHB matrix from crude synthetic esters extracted from the TLC plates. Significant improvements in both reproducibility and sensitivity were realized by using pencil lead as the MALDI matrix. The current methodology will be beneficial to organic chemists since it can provide a guideline for simple and rapid characterization of small organic compounds.

Diastereoselective photochemical radical addition of a cyclic ether to olefins: addition of THF radicals to dialkyl maleates

“…Olefins 1a, 1b, 1d, 1f, THF (2) and DTBP were purchased and used as bought. Olefins 1c 19 and 1e 20 were synthesized according to the reported procedures.…”

Recent Advances in Combinations of TLC With MALDI and Other Desorption/Ionization Mass-Spectrometry Techniques

“…The approach allowed the detection of anthocyanins in red wine, It is important to note, however, that the use of solutions of matrixes can cause secondary chromatographic processes on TLC plates and, hence, analyte spot blurring. This problem can be overcome by using solvent-free matrixes such as graphite-assisted laser desorption/ionization (GALDI) (Han et al, 2011). The sample preparation process in this case looks very simple and convenient because the matrix can be applied on TLC plates by denoting spots with a simple pencil lead.…”

Drawing a different picture with pencil lead as matrix-assisted laser desorption/ionization matrix for fullerene derivatives

“…For pencil lead-MALDI of long alkyl esters of succinic and maleic acid, significant improvements in both reproducibility and sensitivity have been reported. 18 Pencil lead-MALDI analysis of model peptides has been compared with other matrix-free targets and gave only moderate performance. 19 Also, the use of colloidal graphite led to improved results compared to the one of pencil lead for the analysis of low molecular weight analytes.…”