New Use for a Compound as a Matrix in the Specific Detection, Identification and/or Quantification of Alkaloids by MALDI-TOF Mass Spectrometry

The present invention relates to (i) a method of analysing small molecules that may have a mass of < 800 Da, in particular alkaloids, said method being generally referred to as MALDI-TOF-MS (or MALDI Time-of-Flight MAss Spectrometry) which is an acronym for a method of analysis by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, to (ii) a molecule according to formula (I) and to the use thereof as a matrix in such an analysis method

JMS Letters

Desorption/ionization on self-assembled monolayer surfaces (DIAMS) In mass spectrometry, the laser desorption/ionization (LDI) method refers to an overall process by which the energy absorption of a laser beam by a localized region of an irradiated surface leads to the emission of gaseous charged particles. The most important steps involve the rapid dissipation of energy followed by the vaporization of the analyte, which acquires translational energy. Therefore, the direct irradiation of a sample, which induces a very rapid local heating and the absorption in the UV or IR region by the analyte, reduces the ionization efficiency and activates the dissociation of weak bonds during the energy transfer. This constitutes a limitation of the LDI technique, since only fragmented ions are detected even in the case of small-molecule analysis. To circumvent this problem, Karas and Hillenkamp 1 and Tanaka 2 have developed the matrix assisted laser desorption/ionization (MALDI) technique. This method uses a photonabsorbing mediator, i.e. an aromatic matrix molecule, which is co-crystallized with the analyte. The analyte dispersion into the matrix crystals and the structure of the irradiated matrix crystal surface play a key role in the energy dissipation process. In order to overcome these limitations, free-matrix laser ablation/ionization methods have been proposed in the literature. The LDI on porous silicon (DIOS) technique was developed because of the structure of the surface, which in this case provides a scaffold for retaining solvent and analyte molecules, and the UV absorptivity of the substrate, which affords a conversion mode for the transfer of the photon energy to the translational energy, leads to the sample vaporization process. 7 The 'surface-assisted laser desorption/ionization' (SALDI) method uses a thin layer of activated carbon particles immobilized on an aluminum support. 8 In this case, the sample can be directly deposited on the surface plate. An alternative technique uses a suspension of a fine graphite powder or functionalized nanoparticles 9 in a solution of the analyte in an organic solvent. Peptides and organic compounds were then detected in DIOS and SALDI mass spectrometry as protonated molecules and/or as alkali metal adducts. 10, By analogy with the surface properties of a UV-absorbing semiconductor (such as porous silicon), and with regard to the analytical flexibility offered by the possibility of functionalization of activated surfaces, we propose here the use of some organic surfaces in the LDI techniques. This new free-matrix laser desorption ionization method developed is termed desorption/ionization on self-assembled monolayer surfaces (DIAMS) and uses self-assembled monolayers (SAMs). SAMs are defined as two-dimensional films, one molecule thick, covalently assembled at an interface. These organic assemblies result, in most cases, from the reaction in solution between the headgroup function of a molecular constituent and a metal, oxide or semiconductor surface. The synthesis of the SAMs precursor compounds starts from the 2-bromothiophene and is described in Scheme 1. Because of the propensity of the thiol function to oxidation, all characterizations in solution were carried out on the protected alkane-thiol (1). As expected from previous results reported in the literature, the characteristic optical band of 1 is observed at 340 nm

Matrix for specific detection of alkaloids by MALDI-​TOF mass spectrometry

The présent invention relates to a novel bithiophenic matrix for spécifie détection of alkaloids by MALDI-TOF mass spectrometr

Desorption/Ionization on self-Assembled Monolayer Surface (DIAMS) Evaluation of a New Matrix-Free Laser Desorption/Ionization method

Date du colloque&nbsp;: 06/2008</p

Synthesis and evaluation of naphthoic acid derivatives as fluorescent probes to screen advanced glycation end-products breakers

Advanced glycation end-products, namely AGEs, are involved in the pathogenesis of numerous diseases. If AGEs inhibitors are well-known, only few products are described as compounds able to destroy those deleterious products. In this work, we describe naphthoic acid derivatives, particularly 1-(naphthalen-1-yl)propane-1,2-dione 9, allowing the simple and rapid detection of AGEs breakers using a 96-well microplate fluorescence assay. Since the inaugurate publication about AGEs breakers whose activity was demonstrated using HPLC analysis, this work proposes the first assay suitable for automated and high throughput screening of AGEs breakers

A promising method for efficient analysis of secondary metabolites in plant extracts by a matrix-free Desorption/Ionization on self-Assembled Monolayer Surfaces (DIAMS) technique

Plants are one of the major sources for the biologically active organic compounds and play a key role in medicinal chemistry for the treatment of various diseases [1]. DIAMS method is able to determine the secondary metabolites of complex vegetal extracts. The high throughput analyses of vegetal extracts are relatively difficult to perform in MALDI mass spectrometry, since the preparation of the sample involves the co-crystallization of the matrix with the analyte. Moreover irradiation of the matrix ion produces many low-m/z vs high-intensity ions preventing the detection of low molecular weight molecules such as secondary metabolites. We have developed a matrix-free alternative to MALDI analyses by the means of an original desorption/ionization on self-assembled monolayers surfaces (DIAMS) technique [2]. Monolayers were formed by using novel thiophene and coumarin-triazole analogues that absorbs the laser beam at 337nm. We herein disclose our findings with respect to the DIAMS method which is well suitable for the detection and quantification of the low molecular weight compounds that are present in plant extracts. Some of the isoquinoline alkaloids from the root extracts of Thalictrum flavum have been detected by the DIAMS method. Indeed, this technique would be promising suitable for the qualitative and quantitative analysis of polar and non-polar organic components that are widely distributed in the plants, without any preliminary chromatographic resolution [3]

Supramolecular chemistry of helical foldamers at the solid-liquid interface: self-assembled monolayers and anion recognition

The synthesis of a redox-active helical foldamer and its immobilization onto a gold electrode are described. These large molecular architectures are grafted in a reproducible manner and provide foldamer-based self-assembled monolayers displaying recognition properties

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

Within the last 25 years, matrix-assisted laser desorption ionization (MALDI) has become a powerful analytical tool in mass spectrometry (MS). While the method has been successfully applied to characterize large organic molecules such as proteins, sugars and polymers, its utilization for small molecules (≤ 600 Da) is significantly impaired by the coformation of matrix ions. Reducing or eliminating matrix-related signals has been subject of many studies. Some of which propose the enhancement of so-called matrix suppression effects, while others suggest the replacement of matrix molecules by materials such as microporous silicon. Alternatively, the immobilization of matrix molecules by utilizing them as self-assembled monolayers (SAMs) has been discussed. In continuation of this research, the current manuscript focuses on the elucidation of ion formation processes occurring on the surface of light absorbing SAMs. Ion yields obtained by free and immobilized matrix molecules as well as those generated by matrix-free gold film-assisted laser desorption ionization (GF-LDI) were compared. Experiments showed that the formation of strong analyte signals essentially required the presence of free matrix molecules, while the immobilization of the latter severely impaired ionization. The observed effect inversely correlated with the surface coverage of SAMs determined by cyclic voltammetry (CV). Based on these findings, the MS signal generated on light absorbing SAMs could be used supplementary to CV for determining the surface coverage of light absorbing SAMs