Evaluation of a new matrix‐free laser desorption/ionization method through statistic studies: comparison of the DIAMS (desorption/ionization on self‐assembled monolayer surface) method with the MALDI and TGFA‐LDI techniques

Abstract

This work demonstrates that the desorption/ionization on self-assembled monolayer surface (DIAMS) mass spectrometry, a recent matrix-free laser desorption/ionization (LDI) method based on an organic target plate, is as statistically repeatable and reproducible as matrix assisted laser desorption ionization (MALDI) and thin gold film-assisted laser desorption/ionization (TGFA-LDI) mass spectrometries. On lipophilic DIAMS of target plates with a mixture of glycerides, repeatability/reproducibility has been estimated at 15 and 30% and the relative detection limit has been evaluated at 0.3 and 3 pmol, with and without NaI respectively. Salicylic acid and its d(6)-isomer analysis confirm the applicability of the DIAMS method in the detection of compounds of low molecular weight.

Free and immobilized matrix molecules: impairing ionization by quenching secondary ion formation in laser desorption MS

“…A general observation previously made for DIAMS was confirmed at an early stage of the experiments. Any compound that could be detected by DIAMS could also be observed by GF‐LDI, indicating that self‐ionization of analytes is essentially involved into both processes.…”

“…All SAMs, which were so far used for DIAMS experiments share one common structural feature: the bithiophenic chromophore, exhibiting an absorption maximum around 340 nm . This is very close to the emission wavelength of a standard nitrogen laser ( λ = 337 nm) commonly used in MALDI‐TOF instruments.…”

“…Over the last years, another matrix‐free method namely desorption/ionization on self‐assembled monolayers (DIAMS) has been developed . Unlike SALDI, DIAMS replaces classic matrix molecules with light absorbing self‐assembled monolayers (SAMs), which are covalently bound to a gold surface.…”

“…[5] Over the last years, another matrix-free method namely desorption/ionization on self-assembled monolayers (DIAMS) has been developed. [8][9][10] Unlike SALDI, DIAMS replaces classic matrix molecules with light absorbing self-assembled monolayers (SAMs), which are covalently bound to a gold surface. This is a very distinct difference to classic MALDI, where matrix molecules are never covalently attached to the sample plate.…”

Nitroxyl Radical Self‐Assembled Monolayers on Gold: Versatile Electroactive Centers in Aqueous and Organic Media

“…The kinetics for the formation of SAMs, prepared on Au substrate [19] from 1 mm solution of 1 a, 1 b or 1 c in CH 2 Cl 2 or CH 3 CN, were followed by using quartz crystal microbalance (QCM) measurements. By employing, the Langmuir adsorption isotherm model, [20] it is possible to establish that deposition ki- (Figure 1).…”