Continuous-flow Fast Atom Bombardment Research Articles

A Brief Review on Liquid Chromatography-Mass Spectrometry/LCMS and its Application

Liquid Chromatography- Mass Spectrometry is a powerful analytical technique having high Sensitivity and Specificity. LC-MS combines the separation capabilities of Liquid Chromatography with the mass analysis capabilities of Mass Spectrometry. Liquid Chromatography separates the mixture, which is having multiple components, and then Mass Spectrometry provides the Spectral information which is used to identify each separated component. Interfaces are used in LC-MS system to transfer the maximum amount of analyte, remove a significant portion of the mobile phase, and preserves the chemical identity. Different types of Interfaces are used which include Atmospheric-Pressure Ionization, Electrospray Ionization, Atmospheric Pressure Chemical Ionization, Thermospray and Plasma Spray Ionization, Particle Beam Ionization, Continuous Flow Fast Atom Bombardment. LC-MS having a wide range of application in various field which include Pharmaceutical, Drug Development, Forensic Science, Cosmetic, Petrochemistry, Environment, Food Analysis, Biochemical Application. In this article Principle, Instrument and Application are discussed briefly.

Ionization techniques in capillary electrophoresis‐mass spectrometry: Principles, design, and application

A major step forward in the development and application of capillary electrophoresis (CE) was its coupling to ESI-MS, first reported in 1987. More than two decades later, ESI has remained the principal ionization technique in CE-MS, but a number of other ionization techniques have also been implemented. In this review the state-of-the-art in the employment of soft ionization techniques for CE-MS is presented. First the fundamentals and general challenges of hyphenating conventional CE and microchip electrophoresis with MS are outlined. After elaborating on the characteristics and role of ESI, emphasis is put on alternative ionization techniques including sonic spray ionization (SSI), thermospray ionization (TSI), atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), matrix-assisted laser desorption ionization (MALDI) and continuous-flow fast atom bombardment (CF-FAB). The principle of each ionization technique is outlined and the experimental set-ups of the CE-MS couplings are described. The strengths and limitations of each ionization technique with respect to CE-MS are discussed and the applicability of the various systems is illustrated by a number of typical examples.

Applicability of fast-atom bombardment mass spectrometry to the characterization of fulvic acid

A variety of experimental parameters have been evaluated for their effect on the fast-atom bombardment (FAB) mass spectrum of five fulvic acids. Eleven common FAB matrices were evaluated. Only glycerol gave any indication of a fulvic acid spectrum, and this was a very weak signal increase superimposed onto the glycerol spectrum. Continuous-flow FAB was also evaluated using a glycerol matrix and no significant signal was observed in the FAB mass spectrum. Five techniques used to modify the matrix or the sample to enhance a spectrum's signal-to-noise ratio were also studied. Surfactants were added to modify the matrix surface tension, removal of sodium from the fulvic acid samples (to minimize the formation of ([M + Na] +) was accomplished using complexation and ultra-centrifugation, fulvic acid `ions' were preformed in the matrix by the addition of acid or base, and fulvic acid was methylated to increase its hydrophobicity. None of these techniques enhanced the FAB mass spectrum of fulvic acid. The lack of a significant ion intensity attributable to fulvic acid is probably due to its heterogeneous, multi-component nature. Despite some reports in the literature to the contrary, it does not appear that it is possible to characterize fulvic acid by FAB mass spectrometry.

Mycotoxin production by Fusarium proliferatum isolates from rice with Fusarium sheath rot disease.

Twenty samples of unpolished (rough) rice collected in Arkansas and Texas during the 1995 harvesting season from fields exhibiting Fusarium sheath rot disease or panicle blight were previously shown to include 8 samples positive for fumonisin B1 (FB1) in the range 2.2-5.2 ppm, and moniliformin (MON), but no beauvericin (BEA), deoxynivalenol, its derivatives or zearalenone were detected. Fifteen cultures of F. proliferatum were established from the 20 rough rice samples. Single spore isolates of each culture were grown on rice and tested for the production of fumonisins (FB1, FB2, FB3, etc.), MON and BEA. All 15 isolates produced FB1, FB2, MON and BEA in culture on rice. No deoxynivalenol, its derivatives or zearalenone were detected. Seven cultures produced FB1 at > 50 ppm (range 80-230 ppm), with the rest producing FB1 in the range 14-43 ppm. FB2 was produced in the range 5-47 ppm, and those cultures which produced the most FB1 also produced the most FB2. Of the 15 cultures producing MON, 11 produced it at > 100 ppm in the range 188-6018 ppm, with the rest producing in the range 7-64 ppm. BEA was produced in the range 109-1350 ppm. Other derivatives of fumonisins, including FA1, FA2 and partially hydrolyzed FB1, as well as several unknown metabolites including a compound with MW 414, were identified in culture extracts by continuous flow fast atom bombardment with ion spray mass spectrometry (CF/FAB/MS). Further study is needed to identify the factors that control production of FB1, MON and BEA by F. proliferatum in culture and in field samples.

Capillary electrophoresis/tandem mass spectrometry with array detection

Mixtures of standard compounds of biological interest were analyzed by capillary electrophoresis in conjunction with tandem foursector mass spectrometry (MS/MS) using an array detector. Capillary electrophoresis offers extremely high separation efficiencies while array detection allows for the simultaneous acquisition of a large fraction of a tandem mass spectrum and high utilization of the sample ions produced. Consequently, improvements in sensitivity and structural information were observed for the combined techniques in comparison to similar measurements with a four-sector and a single-point detector. Coaxial continuous-flow fast atom bombardment was used to create (M + H) + precursor ions of the separated analytes and their product ion spectra were acquired from femtomole levels in electrophoretic real-time. The limit-of-detection for the acquisition of MS/MS data from electrophoreticallyseparated peptides was 35‐100 fmol. The MS/MS data acquired at these levels showed cleavages of the peptide backbone (i.e. to give a and y ions) and production of immonium ions from the constituent amino acids. Acquisition of the spectra via the array detector is more routine and, at the 100 femtomole level, provides more structurally informative ions and yields better ion statistics than comparable spectra acquired with a point detector.

A comparative evaluation of continuous flow fast atom bombardment and ion spray ionization techniques for the simultaneous determination of alkyltrimethylammonium surfactants by mass spectrometry

A comparative evaluation of continuous flow fast atom bombardment and ion spray ionization techniques for the simultaneous determination of alkyltrimethylammonium surfactants by mass spectrometry

Chromatographic behaviour of the chromium(III) complex of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone

The separation of the two geometrical isomers of the chromium(III) complex of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone was carried out using acetonitrile–water (90:10, v/v) and n-hexane–tetrahydrofuran (70:30, v/v) as the mobile phases for an ODS column and a silica gel column, respectively. Identification of the isomers was performed using a high-performance liquid chromatography–continuous-flow fast atom bombardment–mass spectrometry system. It was found that the fac complex eluted first, followed by the mer complex on the ODS column.

Laser Vaporization/Ionization Interface for Capillary Electrophoresis−Time-of-Flight Mass Spectrometry

Mass spectrometry (MS) is usually coupled on-line with capillary electrophoresis (CE) to analyze biomolecules by using electrospray ionization or continuous-flow fast-atom bombardment. We present a new design for laser vaporization/ionization time-of-flight mass spectrometry. CE, with its low flow rate (<1 μL/min), is highly compatible with MS, even if the total column effluent is introduced directly. A UV laser is used to vaporize and ionize the solution eluting from the column. There is no need to have a makeup solvent. Using this system, we have analyzed a group of amines and peptides. The concentration detection limit of serotonin is in the 10(-)(7) M level. The separation and identification of an amine mixture by CE/MS demonstrates the complementary nature of the information.

Analytical Study of Free and Ester Bound Benzoic and Cinnamic Acids of Gum Benzoin Resins by GC-MS and HPLC-frit FAB-MS

Sumatra benzoin resins originating from two species of Styrax were studied using modern analytical techniques. Analysis of these types of resins usually involves several steps including alkaline hydrolysis, derivatization of the polar groups and chromatography. Two different resins, and three different qualities from each resin, were investigated using a fast analytical method which omits the hydrolysis step and makes it possible to identify all of the individual components of the resin in one gas-chromatography–mass spectrometry measurement. Resins from both Styrax benzoin Dryand and S. paralleloneurum Perk contain free cinnamic and benzoic acids and their corresponding esters with p-coumaryl and coniferyl alcohols, although in different relative amounts. Pinoresinol and some higher molecular weight esters of cinnamic and benzoic acids were also found. The structure of these compounds was verified by high performance liquid chromatography–continuous flow fast atom bombardment mass spectrometry. For quantitation, gas chromatography with flame ionization detection was performed. Molecular response factors of the identified compounds were calculated as correction factors of the peak areas. © 1997 by John Wiley & Sons, Ltd.

Liquid chromatography/mass spectrometry of carotenoids

Abstract

Characterization of neuropeptide processing by fast atom bombardment mass spectrometry.

Fast atom bombardment (FAB) was introduced as a new ionization technique () in 1981 by M. Barber and his coworkers. This was a breakthrough in the analysis of unstable and involatile compounds such as peptides, which were difficult to study by other ionization methods. FAB employs a particle beam consisting of the neutral atoms of xenon or argon. The gas atoms are first ionized and accelerated in the FAB gun and then neutralized on the counter-electrode. The beam, directed toward the sample that is deposited on the probe tip, ionizes and sputters charged particles that are then accelerated in the ion source and analyzed. The sample needs to be added to a viscous, chemically inert, and relatively involatile matrix, which allows a long-term analysis of a target compound. The most commonly used matrix remains glycerol. However, other substances have also been applied for the same purpose (see Section 3.5.). In contrast to electrospray-ionization mass spectrometry (ES1 MS, see Chapter 13), the FAB technique produces molecular ions, corresponding to the mass of intact, charged molecules and designated as [M+H]+ or [M-H]− (positive- or negative-ion mode, respectively). Interpretation of the data obtained is simpler than in ES1 because transformation of the spectra is not necessary, and often fragment ions appear along the spectrum, providing sequence information sufficient to reveal the primary structure of the peptide. Compared to other ionization techniques such as ES1 MS or matrix-assisted laser desorption ionization time-of-flight MS (MALDI TOF) (see Chapter 14), the major disadvantages of the FAB technique are: limited measuring range at a full accelerating voltage (see Note 1); and sensitivity (see Notes 1 and 2). Moreover, strong signals belonging to the matrix clusters may obscure analysis. Problems concerning sensitivity and possible connection to liquid chromatography/capillary electrophoresis systems have successfully been overcome by application of continuous-flow FAB (CF FAB, dynamic FAB) where the sample solution is loaded into the instrument via a fused silica capillary ().

A Comparison of Fast-atom Bombardment and Electrospray as Methods of Ionization in the Study of Sulphated- and Sulphonated-lipids by Tandem Mass Spectrometry

In recent years electrospray has become the most popular ionization technique for the analysis of biomolecules. In the present study, we have compared the electrospray and continuous-flow fast-atom bombardment methods of sample introduction and ionization for the analysis of sulphated and sulphonated lipids by tandem mass spectroscopy. The tandem mass spectra obtained when using the two ionization techniques were similar; however, small differences were evident. These differences indicate that the precursor ions generated by fast-atom bombardment and electrospray have different internal energies. The two ionization techniques give similar sensitivities for the recording of collision-induced dissociation spectra. Complete structural information can be obtained from 5 to 50 ng of lipid

Urinary bile acids and peroxisomal bifunctional enzyme deficiency

The biosynthesis of normal bile acids involves beta-oxidation of the 8-carbon side-chain of cholesterol, in addition to numerous modifications of the sterol nucleus. Because beta-oxidation of the sterol side-chain has been localized to the peroxisome, bile acid analysis has been suggested to be useful in the diagnostic evaluation of individuals suspected of having peroxisomal disorders. Although data from subjects with generalized peroxisomal disorders support this, few data exist regarding the bile acids in individuals having single peroxisomal beta-oxidation enzyme disorders. In this study, we analyzed the urinary bile acids from 12 patients with peroxisomal bifunctional protein deficiency using continuous flow fast atom bombardment mass spectrometry. All 12 patients had abnormal spectra, although their ion profiles and rank order of intensity of ions varied considerably. Ten of 12 individuals had abnormal spectra with presence of taurine-conjugated tetrahydroxycholestenoates, allowing a definite diagnosis of a peroxisomal beta-oxidation defect and a presumptive diagnosis of bifunctional protein deficiency; the other two cases were nondiagnostically abnormal. The strengths and limitations of urinary bile acid analysis for the diagnosis of peroxisomal beta-oxidation disorders are discussed.

Urinary bile acids and peroxisomal bifunctional enzyme deficiency

The biosynthesis of normal bile acids involves beta-oxidation of the 8-carbon side-chain of cholesterol, in addition to numerous modifications of the sterol nucleus. Because beta-oxidation of the sterol side-chain has been localized to the peroxisome, bile acid analysis has been suggested to be useful in the diagnostic evaluation of individuals suspected of having peroxisomal disorders. Although data from subjects with generalized peroxisomal disorders support this, few data exist regarding the bile acids in individuals having single peroxisomal beta-oxidation enzyme disorders. In this study, we analyzed the urinary bile acids from 12 patients with peroxisomal bifunctional protein deficiency using continuous flow fast atom bombardment mass spectrometry. All 12 patients had abnormal spectral, although their iron profiles and rank order of intensity of ions varied considerably. Ten of 12 individuals had abnormal spectra with presence of taurine-conjugated tetrahydroxycholestenoates, allowing a definite diagnosis of a peroxisomal beta-oxidation defect and a presumptive diagnosis of bifunctional protein deficiency; the other two cases were nondiagnostically abnormal. The strengths and limitations of urinary bile acid analysis for the diagnosis of peroxisomal beta-oxidation disorders are discussed. © 1996 Wiley-Liss, Inc.

Identification of radical adducts formed in the reactions of unsaturated fatty acids with soybean lipoxygenase using continuous flow fast atom bombardment with tandem mass spectrometry.

Structures of alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) radical adducts formed in the reactions of soybean lipoxygenase with linoleic acid, linolenic acid, and arachidonic acid were determined using continuous flow fast atom bombardment (CF-FAB) combined with tandem mass spectrometry. The radical adducts of these lipoxygenase-dependent reactions were: n-octanoic acid radical, 12,13-dihydroxylinoleic acid radical, 12,13-epoxylinoleic acid radical, and n-pentyl radical from linoleic acid; n-octanoic acid radical, ethyl radical, and cis/trans and/or positional isomers (1- and 3-pentenyl) of pentenyl radical from linolenic acid; and 14,15-epoxyarachidonic acid radical and n-pentyl radical from arachidonic acid. Of these radical adducts, the n-octanoic acid radical from linoleic and linolenic acid, the ethyl radical from linolenic acid, and the 12,13-dihydroxylinoleic acid radical are identified for the first time in the reactions of soybean lipoxygenase. Thus the CF-FAB combined with tandem mass spectrometry employed here, by which both radical adducts and their fragment ions can be detected, is shown to be a powerful tool in the structural identification of free radicals.

Biosynthesis of fumonisin and aal derivatives by Alternaria and Fusarium in laboratory culture.

Cultures of Fusarium moniliforme and Alternaria alternata f. sp. lycopersici were grown in the laboratory and analyzed for various fumonisin derivatives. Analyses were made by continuous flow fast atom bombardment and ionspray mass spectrometry interfaced to microcapillary HPLC. Besides FB1, FB2 and FB3 derivatives, two isomers of the one-armed FB1 (protonated molecular ion at m/z 564) and two isomers of the one-armed FB2 (m/z 548) were found. Two different isolates of A. alternata when grown in culture yielded FB1, FB2 and FB3. One of them also yielded the one-armed FB1 which was identical to that metabolite found in Fusarium and naturally infected corn. FB1, FB2 and FB3 have been found in 2 different isolates of Alternaria alternata, both obtained from tomato.

γ‐Glutamylglutamine and Taurine Concentrations Are Decreased in the Cerebrospinal Fluid of Drug‐Naive Patients with Schizophrenic Disorders

HPLC and gas chromatography-mass spectrometry analyses of 18 amino acids, N-acetylaspartate, N-acetylaspartylglutamate, and 5-hydroxyindoleacetic acid, derived from serotonin, and homovanillic acid, derived from dopamine, were performed in CSF collected from a group of patients with schizophrenia who either had been drug free for at least 1 year (n = 5) or were drug naive for psychotropic drugs (n = 21) and in 15 control subjects. Significant differences were found only for taurine (15% lower in the patients) and isoleucine (7% higher). A number of unidentified substances were detected, one of which proved to be markedly reduced (16%) among the schizophrenic patients. Liquid chromatography-mass spectrometry with continuous flow-fast atom bombardment interface allowed us to identify this substance as gamma-glutamylglutamine. The decreased level of gamma-glutamylglutamine may reflect a deficiency in the gamma-glutamyltransferase system, a system probably involved in glutamate uptake, or a deficiency in glutamine, an important precursor of releasable glutamate. Although glutamate was nonsignificantly reduced in the patients, it was one of the five substances (including gamma-glutamylglutamine) that were necessary for the best discrimination between the schizophrenic patients and the controls. These findings support the notion that the glutamatergic system is affected in schizophrenic disorders. In addition, they underscore the need to apply rigid bioanalytical techniques and use drug-naive patients to gain in-depth information on the pathophysiology of brain disorders such as schizophrenia.

Liquid chromatography combined with thermospray and continuous-flow fast atom bombardment mass spectrometry of glycosides in crude plant extracts

In crude plant extracts, constituents of biological or pharmaceutical interest often exist in the form of glycosides. Off-line mass spectral investigations of these metabolites require soft ionisation techniques such as desorption chemical ionisation (DCI) or fast atom bombardment (FAB) if information on molecular mass or sugar sequence is desired. In LC-MS, glycosides can be ionised by using thermospray (TSP), continuous-flow fast atom bombardment (CF-FAB) or other interfaces. These techniques are thus potentially applicable to the on-line analysis of glycosides and can be applied to plant extract analysis. Thermospray (TSP) used with ammonium acetate as buffer provides mass spectra similar to those obtained with DCI-MS using NH 3 and is potentially applicable to the on-line analysis of relatively small glycosides bearing no more than three sugar units. CF-FAB provides cleaner MS spectra than static FAB due to the lower concentration of the matrix used and can be applied to more polar compounds such as glycosides with a larger number of sugars. The use of a special setup involving post-column addition of the buffer or the matrix and splitting allows LC-UV, TSP LC-MS and CF-FAB LC-MS to be performed with the same standard HPLC conditions. Different crude plant extracts containing various types of glycosides with one to eight sugar units have been analysed by both TSP and CF-FAB. Cardenolides from Nerium odorum (Apocynaceae) and saponins from Swarzia madagascariensis (Leguminosae), Aster scaber and Aster tataricus (Asteraceae) have been studied by LC-MS. The combination of these two interfaces for the HPLC screening of crude plant extracts is discussed.

HPLC-continuous-flow fast atom bombardment mass spectrometry (HPLC-CFFAB) — a convenient method for the analysis of bile acids in bile and serum

In order to analyse bile acids in biological matrices, e.g. rat bile and human serum, high performance liquid chromatography (HPLC) was coupled to continuous-flow fast atom bombardment mass spectrometry (CFFAB-MS). A gradient elution system which had already proved to be well suited for the quantitative determination of conjugated bile acids in bile was modified to allow HPLC-CFFAB-MS-coupling. Due to the sensitivity of this coupling method it is possible to obtain more information about the biliary bile acid pattern and species-specific secondary bile acids. Furthermore, we were able to identify obviously unknown bile acid species in rat bile which most likely classify as mono-oxo and di-oxo-taurocholates (MW 513 Da, 511 Da) and mono-oxo-glycocholates (MW 463 Da). In the present study we show that using this system it is possible to determine both conjugated and unconjugated as well as sulfated bile acids, without time consuming group separation and derivatization, from rat bile and human serum. In addition, it is suggested that the method presented here should be considered for use in routine analysis.

Incorporation of sample stacking techniques into the capillary electrophoresis CF-FAB mass spectrometric analysis of DNA adducts.

Sample stacking is used to improve the detection limits of capillary zone electrophoresis coupled to continuous flow fast atom bombardment mass spectrometry for the analysis of DNA adducts. It was found that, with stacking, the concentration detection limit of deoxynucleotide adducts could be improved by as much as 3 orders of magnitude, thereby bringing it into the 10(-8) M range. In addition, the mass spectrometric mass detection limits of a model acetylaminofluorene deoxyguanosine 5'-monophosphate adduct were found to be in the low picomole range for full scanning and the low femtomole range for multiple reaction monitoring of a selected fragmentation. The techniques have been applied to the analysis of adducts formed in the in vitro reaction of N-acetoxy-N-acetyl-2-aminofluorene with DNA.