Matrix compounds for fast atom bombardment mass spectrometry

Gower, John L.

doi:10.1002/bms.1200120502

Cited by 139 publications

(16 citation statements)

References 53 publications

(1 reference statement)

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“…The program then initializes the appropriate variables (Step 3) and starts the iteration by fixing the value of the reduction extent (BestRedox) to zero (Step 3a). Using this value of BestRedox and with the aid of a random generator that provides values for the background (BestBack), SRBC calculates values for the peak intensities Ik according to Eqns (1) to (4). SRBC does this 10000 times and for each value of BestBack (B) it simulates the experimental isotopic peak ratios, A$, (5) which are then compared to the experimentally measured isotopic peak ratios A : ; .…”

Section: Resultsmentioning

confidence: 99%

An approach to the quantiative study of reduction processes occurring in fast‐atom bombardment/liquid‐assisted secondary‐ion mass spectrometry

Bertrand

Visentini

Paul

et al. 1992

Rapid Comm Mass Spectrometry

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An approach which allows the determination of the specific effects of experimental parameters on the extent of reduction observed in fast-atom bombardmenthiquid-assisted secondary-ion mass spectrometry (FAB/LSIMS) has been developed. The methodology is based on the isolation of the different components-background, reduction extent, and isotopic abundances-which contribute to peak intensities in the molecular-ion cluster. The individual contributions of reduction and background are calculated by an algorithm SRBC (simulated reduction and background calculations) which utilizes a Monte-Carlo method to optimize the values obtained for these variables. This approach has been used to examine the effects of analyte concentration, primary-beam energy and beam density on the extent of reduction in FAB/LSIMS experiments. The results obtained indicate that the beam energy has no significant effect on the apparent reduction, as measured by the experimental (A + 2)IA isotopic peak ratio, while analyte concentration and beam density effects are observed. However, background and reduction data generated by SRBC demonstrate that in some cases there is little effect of these parameters on the true reduction of the analyte and that the increase in apparent reduction with the variation in these parameters results mainly from an artefact created by an increase in the background signal at lower concentrations and higher beam densities.The use of desorption-ionization techniques such as fast-atom bombardment (FAB) and liquid-assisted secondary-ion mass spectrometry (LSIMS) has, over the last decade, expanded the scope of mass spectral analysis. The most unique feature of FAB/LSIMS is the use of a liquid matrix in which the analyte is dissolved.',' Initially, glycerol was employed as the liquid matrix'.' but other materials have since been utilized and these have been the subject of excellent reviews.s5 Several physical and chemical phenomena related, to the use of a li uid matrix have been observed in FAB/LSIMS analysis%7 and although numerous studies have been directed at the investigation of fundamental processes occurring in FAB/LSIMS&" our knowledge of the mechanisms involved is still deficient. One of the phenomena which has been observed under FAB conditions and that has attracted considerable interest is the occurrence of reduction processes in the matrix under bombardment .lLZ9 These reduction processes, which cause the intensities of A + n peaks (A = (M+ H), n 3 1) to be higher than the theoretical values calculated using the natural abundances, have been shown to involve electrons and/or hydrogen 14,21 and have been observed in several chemical systems.The extent of reduction observed in FABILSIMS depends on the nature of the analyt~,'"'6~2~''~3~32 the nature of the r n a t r i~, '~~'~~'~~'~~~~~~~ the presence of matrix additive^'^^'^^'^ and other experimental parameters. Matrices that have electrodradical scavenging properties such as 3-nitrobenzylalcohol (NBA), 2-hydroxyethyl disulfide (HEDS) and 4-hydroxybenzenesulfonic ...

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Section: Resultsmentioning

confidence: 99%

An approach to the quantiative study of reduction processes occurring in fast‐atom bombardment/liquid‐assisted secondary‐ion mass spectrometry

Bertrand

Visentini

Paul

et al. 1992

Rapid Comm Mass Spectrometry

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“…The influence of various properties of liquid matrices on the FAB mass spectrometry of involatile molecules has been reviewed previously. [10][11][12] In addition, the physical and chemical properties of the more common liquid matrices have been tabulated by Cook et al 13 with the specific intention of assisting rational matrix selection in FAB-MS.…”

Section: Choice Of Matrix Componentsmentioning

confidence: 99%

Two‐phase Matrix‐assisted Laser Desorption/Ionization: Matrix Selection and Sample Pretreatment for Complex Anionic Analytes

Dale¹,

Knochenmuss²,

Zenobi³

1997

Rapid Commun. Mass Spectrom.

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Two-phase matrices, consisting of a binary mixture of solid particulates and a low vapour pressure liquid, are shown to be effective for the production of both positive-ion and negative-ion laser desorption/ionization mass spectra (LDI-MS). It was found that matrix selection can be guided by criteria developed previously for fast-atom bombardment mass spectrometry. Two-phase matrix-assisted (MA)LDI-MS of a variety of complex anionic analytes is presented. Sample pre-treatment using 'drop dialysis', or exposure to an acid-activated Nafion® cation-exchange membrane, substantially enhances the quality of negative-ion mass spectra. © 1997 by John Wiley & Sons, Ltd. Received 21 November 1996; Accepted 30 November 1996 Rapid Commun. Mass Spectrom. 11, 136-142 (1997 1-3 It is thought that laser radiation is absorbed by the solid particulates, causing desorption/ionization via rapid thermal evaporation of the liquid matrix. The binary mixtures have a number of advantages over their solid counterparts for matrixassisted laser desorption/ionization mass spectrometry (MALDI-MS). Most significantly, no co-crystallization of the matrix and analyte is required, and analyte diffusion through the liquid component can result in thorough mixing and homogenization of the sample. In addition, the liquid matrix is not required to have a UV chromophore. It has been shown previously 3 that, in two-phase matrices, the liquid provides protons and cations to the analyte, enhances analyte ion yields, improves resolution and increases signal stability and uniformity.The separation of the energy absorption (solid particulates) and solvent (liquid matrix) functions adds a new degree of flexibility which we use here to extend the application of two-phase MALDI to include the negative-ion mass spectrometry of involatile, intermediate-molecular-weight analytes. The choice of liquid matrices and solid particulates is discussed in this context. It is noted that liquid matrix selection can be guided by similar criteria to those previously determined in fast-atom bombardment mass spectrometry (FAB-MS). It is demonstrated that a two-phase matrix, consisting of diethanolamine and silicon particulates, can be used to obtain the mass spectra of complex organic phosphates and sulphonates, which are most readily analysed in the negative-ion mode. Sample pretreatment by dialysis and cation exchange is demonstrated to significantly improve mass spectral quality for these analytes. The use of both membrane drop dialysis and Nafion® cation exchange membranes is also discussed. EXPERIMENTALThe experiments were performed on a home-built 2 m linear time-of-flight mass spectrometer. Ions were extracted from the source region using a static 25 kV acceleration potential. Desorption was performed using the 337 nm output from a nitrogen laser (Laser Science Inc. VSL-337ND-T), incident at ca. 30° to the sample surface. Laser attenuation was achieved using glass slides and an adjustable iris. The laser spot size was estimated to be an ellipse of axes ca. 0.1 × 0.2 mm...

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“…Initially, glycerol was the only matrix used 5 but before long other organic solvents of low volatility were found to yield improved spectra; among them 3-nitrobenzyl alcohol (3-NBA) 6-8 2-nitrophenyl octyl ether (2-NPOE), 6,9 paraffin, [10][11][12] sulpholane, [13][14][15] concentrated sulfuric acid 16 and others. 9,17,18 Since that time several reviews on the matrix aspect [19][20][21][22][23] and on the processes of desorption and ion formation [24][25][26] under FAB conditions have appeared. It is commonly accepted that a good matrix for FAB-MS has to meet the following requirements: 19,22 1) The samples must be soluble in the matrix, otherwise addition of co-solvents like dimethyl formamide (DMF) or dimethyl sulphoxide (DMSO) becomes necessary.…”

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confidence: 99%

Use of protic and aprotic solvents of high volatility as matrices in analytical low-temperature fast-atom bombardment mass spectrometry

Gross¹

1998

Rapid Commun. Mass Spectrom.

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Matrix compounds for fast atom bombardment mass spectrometry

Cited by 139 publications

References 53 publications

An approach to the quantiative study of reduction processes occurring in fast‐atom bombardment/liquid‐assisted secondary‐ion mass spectrometry

An approach to the quantiative study of reduction processes occurring in fast‐atom bombardment/liquid‐assisted secondary‐ion mass spectrometry

Two‐phase Matrix‐assisted Laser Desorption/Ionization: Matrix Selection and Sample Pretreatment for Complex Anionic Analytes

Use of protic and aprotic solvents of high volatility as matrices in analytical low-temperature fast-atom bombardment mass spectrometry

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