Electrospray Ionization Mass Spectrometry of Surfactant-Metal Ions Attachment: Sensitivity and in-Source Fragmentation (original) (raw)
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2009
Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) is used to investigate the reaction of non-ionic ethylene oxide based surfactants, with divalent metal ions. The effect of capillary-skimmer potential difference and the ion residence time in the hexapole ion trap in the external ion optic of the FT mass spectrometer were systematically investigated for the single oligomer systems, hexaethylene glycol monodecyl ether (HEGMDE) interacting with the nitrate salts of Cd(II) in methanol. It is observed that these variables impact significantly on the type of ions observed in the ESI experiment and hence the mass spectra and so it is essential to identify their contribution prior to undertaking any binding efficiency experiments. Collision induced dissociation in the capillary skimmer region and by on resonance irradiation is used to investigate structures and fragmentation pathways. In particular the loss of HNO3 in the nitrate salts is a f...
Negative ion field desorption mass spectrometry of anionic surfactants
Fresenius Journal of Analytical Chemistry, 1982
Die Felddesorptions-Massenspektrometrie negativer Ionen wurde zur direkten Mischungsanalyse von Detergentien, die anionaktive Tenside enthalten, angewendet. Die Massenspektren zeigen eine hohe Selektivität der Methode für den Nachweis der Sulfonate (Konzentrationsgrenze 10−5 mol/l). Die Spektren enthalten weder Fragmentionen noch Ionisierungsprodukte nichtionischer Komponenten der Mischung. Negative ion field desorption mass spectrometry has been applied to detergents containing anionic surfactants. The mass spectra demonstrate a high selectivity for the detection of the sulphonates (concentration limit 10−5 mol/l). The spectra do not contain fragment ions nor ionization products from non-ionic components of the mixture.
The analytical potential of the complexation of non ionic surfactants such as 1-octyl-β-D-glucopyranoside and Tween-20 with Zn(II), Cd(II), and Cu(II) was investigated by positive-ion electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. The most favorable M(II)/ 1-octyl-β-D-glucopyranoside association involves the metal attached to the deprotonated hydroxymethyl group and the hemiacetal oxygen. The binding efficiencies for 1-octyl-β-D-glucopyranoside and Tween-20 with Zn(II), Cd(II), and Cu(II) are studied.The metal binding order for 1-octyl-β-1-octyl-β-D-glucopyranosideis Cu(II) > Zn(II) > Cd(II).
Journal of Chromatography A, 2008
Non-derivatized Brij 58 oligomers were analyzed by using non-aqueous capillary electrophoresis (NACE) hyphenated to mass spectrometry (ion trap). The separation of this neutral polyethylene oxide surfactant was based on its complexation with ammonium cation in methanolic medium. Cationic complexes were formed within the capillary and migrated against the anodic electroosmotic flow. The latter was obtained by using a pre-treatment of the capillary with hexadimethrine bromide. By optimizing mass detection and the separation conditions separately, it was demonstrated that two different salts had to be used. Ammonium acetate was used in the sheath liquid to optimize detection sensitivity whereas ammonium iodide was used in the running electrolyte in order to obtain the more appropriate electroosmotic flow for the separation. Despite an aspiration effect due to the hyphenation with MS. that did not allow us to obtain a baseline resolution for the entire mixture, we were able to visualize and characterize more than 25 oligomers of Brij 58. As regards detection sensitivity, the limits of detection (LOD) were estimated at about 7.5 ng for the entire distribution of Brij 58 and 15 pg for C 16 E 5 or C 16 E 6 used as standards.
Selective enhancement of ion signal of charged surfactant in fast atom bombardment mass spectrometry
Journal of Mass Spectrometry, 1995
The addition of sodium dodecylsulfate (SDS) to a glycerol solution containing equal concentrations of a series of quaternary amines has been found to have a significant effect on the relative fast atom bombardment (FAB) response factors for each analyte. The relative FAB signals of quaternary amines with different alkyl chain length were found to be either enhanced or degraded under different SDS concentrations. The effect observed can be correlated with the difference in the rate of ion-pair precipitate formation between negatively charged dodecylsulfate and positively charged quaternary amine. It is also demonstrated that, in much the same way, SDS can be used to enhance the response of the less surface-active component in an industrial dye by FAB analysis.
Review: Mass spectrometry of surfactant aggregates
European Journal of Mass Spectrometry, 2011
In contrast with the enormous amount of literature produced during many decades in the field of surfactant aggregation in liquid, liquid crystalline and solid phases, only a few investigations concerning surfactant self-assembling in the gas phase as charged aggregates have been carried out until now. This lack of interest is disappointing in view of the remarkable theoretical and practical importance of the inherent knowledge. The absence of surfactant–solvent interactions makes it easier to study the role of surfactant–surfactant forces in determining their peculiar self-assembling features as well as the ability of these assemblies to incorporate selected solubilizate molecules. Thus, the study of gas-phase surfactant and surfactant–solubilizate aggregates is a research subject which has exciting potential, including mass and energy transport in the atmosphere, origin of life and simulation of supramolecular aggregation in interstellar space. On the other hand, the structural and...
Capillary Electrochromatography−Mass Spectrometry of Nonionic Surfactants
Analytical Chemistry, 2007
The Triton X (TX)-series are alkylphenol polyethoxylates -type nonionic surfactants of varying numbers of ethylene oxide units. Applications include industrial and household detergent formulations as well as emulsifying agents. For analysis of these surfactants, capillary electrochromatography-electrospray ionization-mass spectrometry (CEC-ESI-MS) offers several unique advantages over the traditional hyphenation methods based on HPLC-MS. These include higher plate numbers attainable in CEC-MS, as well as more compatible flow rate (submicroliter) when coupled to ESI-MS and, perhaps most importantly, less consumption of toxic and costly organic solvents. In this work, different CEC-ESI-MS parameters such as mobile-phase composition, sheath liquid, and spray chamber parameters were optimized to provide suitable and sensitive analysis of short-, medium-, and long-chain length (e.g., n ) 1-16) TX-series nonionic surfactants. The optimized CEC-ESI-MS conditions were mobile phase containing 90/10 ACN/2.5 mM Tris, pH 8, sheath liquid containing 50/50 MeOH/10 mM HCO 2 NH 4 delivered at 5 µL/min, spray chamber set to drying gas flow of 6 mL/ min, nebulizer pressure of 5 psi, and drying gas temperature set to 200°C. This optimization is followed by the more challenging separation of very long chain TX-series with a large number (n ) 30-70) of ethoxy units, which were initially found to exhibit extreme retention using the developed method. It was observed that through the addition of small volume fraction of polar-aprotic tetrahydrofuran solvent to the running buffer, the retention time could be significantly reduced thus enhancing the feasibility for CEC-ESI-MS analysis of these very long chain nonionic surfactants for the first time. The detection limit was ∼37 µg/mL total octylphenol ethoxylate for TX-45; acceptable precision of migration time (<1% RSD, n ) 3) and peak area (∼4% RSD, n ) 3) were achieved.