Atom Bombardment Mass Spectrometry Research Articles

Gd-Complexes of New Arylpiperazinyl Conjugates of DTPA-Bis(amides): Synthesis, Characterization and Magnetic Relaxation Properties.

Two new DTPA-bis(amide) based ligands conjugated with the arylpiperazinyl moiety were synthesized and subsequently transformed into their corresponding Gd(III) complexes 1 and 2 of the type [Gd(L)H2O] nH2O. The relaxivity (R1) of these complexes was measured, which turned out to be comparable with that of Omniscan®, a commercially available MRI contrast agent. The cytotoxicity studies of these complexes indicated that they are non-toxic, which reveals their potential and physiological suitability as MRI contrast agents. All the synthesized ligands and complexes were characterized with the aid of analytical and spectroscopic methods, including elemental analysis, 1H-NMR, FT-IR, XPS and fast atom bombardment (FAB) mass spectrometry.

Novel phosphorylation of aldrin-trans-diol by dieldrin-degrading fungus Mucor racemosus strain DDF

Dieldrin is one of the most persistent organic pollutants, and its oxidative degradation pathways by aerobic microorganisms to 6,7-trans-dihydroxydihydroaldrin (otherwise known as aldrin-trans-diol) and 9-hydroxydieldrin are well documented. The dieldrin-degrading fungus, Mucor racemosus strain DDF, can decrease dieldrin levels with simultaneous production of a small amount of aldrin-trans-diol. A reduction in the levels of aldrin-trans-diol by strain DDF has also been observed. Based on these results, it has been suggested that strain DDF transforms dieldrin to more polar compounds via aldrin-trans-diol. We have conducted a study to identify the metabolites arising from aldrin-trans-diol. The results showed that strain DDF gave reduced levels of aldrin-trans-diol and also produced unknown metabolites. Ultra performance liquid chromatography-electrospray ionization-mass spectroscopy (UPLC-ESI-MS) analysis indicated the metabolites to be either sulfated- or phosphorylated- derivatives of aldrin-trans-diol, but with the metabolites retaining six chlorine atoms. Therefore, the candidate derivatives were synthesized and the retention times of the natural metabolite and the synthetic phosphate were compared. As a result of a co-injection experiment, the metabolites were determined to be aldrin-trans-diol exo- and endo-phosphates. These results were also supported by high-resolution-fast atom bombardment-mass spectrometry (HR-FAB-MS) of the natural metabolite (Δ = 0.63 ppm). Phosphorylation of aldrin-trans-diol is the first reported example of phosphate conjugation in microorganisms.

Mass-spectrometric study of the formation of silver nanoclusters in polyether media: 2. Fast atom bombardment and modeling

Within the problem of the synthesis of silver nanoclusters and nanoparticles in polyether media, systems containing silver nitrate AgNO3 and low-molecular-weight polyethers, poly(ethylene glycol) PEG-400 or oxyethylated glycerol OEG-5, were studied by fast atom bombardment (FAB) mass spectrometry. The formation of stable clusters of polyether oligomers (M m ) with silver cations M m · Ag+ was shown, in agreement with the previous data of laser desorption/ionization. Quantum-chemical DFT calculations have shown that the M m · Ag+ clusters are stabilized by wrapping of the polyether chain around the silver cation with the cation coordinating ether oxygen atoms. Silver nanoclusters were not found in the FAB mass spectra of liquid systems, but Ag n + clusters were detected for silver nanoparticles separated from the reaction medium. No products of chemical transformations of PEG-400 or OEG-5 were observed by FAB. A plausible mechanism of the reduction of silver cations involving nitrate anions is discussed.

Gamakamide-E, a Strongly Bitter Tasting Cyclic Peptide with a Hydantoin Structure from Cultured Oysters Crassostrea gigas

A new cyclic peptide (six-membered amino acid), gamakamide-E (L-Leu-L-Met (SO)-L-Me-Phe-L-Leu-D-Lys-L-Phe), was isolated as a strongly bitter tasting compound from cultured oysters, Crassostrea gigas. The molecular formula of C 43 H 61 N 7 O 8 S was deduced from high resolution fast atom bom bardment mass spectrometry (HR FAB-MS) ([M + H] + m/z 836.4356 △= -2.4 mmu). Its unique structure including a hydantoin structure was firstly elucidated by nuclear magnetic resonance (NMR) analysis. Stereo chemistries of constituent amino acids were determined by chiral high performanced liquid chromatography analysis of natural and synthesized peptides.

Synthesis and Characterization of η3-Allyl Palladium(II) Complexes with Tetraalkyldiphosphine Disulfides, R2P(S)P(S)R2 (R=Me, Et, nPr, nBu, Ph)

New allyl-palladium tetraalkyl(phenyl)diphosphine disulfide complexes, [(η3-CH2CMeCH2)Pd(tmps)]Cl, [(η3-CH2CMeCH2) Pd(teps)]Cl, [(η3-CH2CMeCH2)Pd(tpps)]Cl, [(η3-CH2CMeCH2) Pd(tbps)]Cl, [(η3-CH2CMeCH2)Pd(tPhps)]Cl, and [(R2P(S)P(S) R2) R=Me, (tmps); Et, (teps); nPr, (tpps); nBu, (tbps); Ph, (tPhps)] have been prepared from the addition of tetraalkyl (phenyl)diphosphine disulfide to [(η3-CH2CMeCH2)Pd(μ-Cl)]2. All the complexes have been characterized by elemental analysis, Fourier-transform infrared (FT-IR), nuclear magnetic resonance (1H-NMR and 31P-{1H}-NMR) spectroscopy, and fast atom bombardment (FAB) mass spectrometry. The spectroscopic studies suggest that ligands are cis-chelate bidentate coordination, forming five-membered Pd-S=P-P=S palladacycles, with the η3-allyl group completing the coordination sphere.

Thermal Decomposition Kinetics of Labile Chromium Complex with Benzoic Acid

Complex [CrO2(C7H5O2) C2H5OH) (H2O)2] was prepared by using benzoic acid. Its spectral characterization was done by using Elemental analysis (C and H), Inductively coupled plasma optical emission spectroscopy (ICP - OES), Ultraviolet - visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and Fast Atomic Bombardment (FAB) Mass spectrometry. Whereas thermal decomposition was investigated by differential scanning calorimetric (DSC). The low value of activation energy of exothermic change indicated lability of complex.

ChemInform Abstract: Chemical Reactions in Fast Atom Bombardment Mass Spectrometry

Examples of various chemical reactions occurring in the matrix or in the selvedge region in fast atom bombardment (FAB) mass spectrometry are discussed. These are categorized as oxidations and reductions; substitutions; clusterings and additions; and sample decomposition or transformation. Some reactions observed showed significant time behaviour and in one case it was possible to determine rate constants. These data suggest that chemical reactions can be accelerated significantly by fast atom bombardment.

Spectroscopy, Electrochemistry, and Structure of 3d-Transition Metal Complexes of Thiosemicarbazones with Quinoline Core: Evaluation of Antimicrobial Property

ABSTRACT A series of Co(II), Ni(II), Cu(II), and Zn(II) complexes of quinoline-thiosemicarbazones was prepared. The Schiff base ligands that provide N, O, and S donor atoms for ligation are synthesized by the condensation of 2-hydroxy-3-formylquinoline with substituted thiosemicarbazides in ethanol. The ligands and complexes are characterized by elemental analysis, infrared, 1H NMR, UV-Vis, fast atom bombardment (FAB) mass spectroscopy, and electron spin resonance (ESR) spectral studies followed by magnetic susceptibility and conductivity measurements. The ligand-to-metal ratio is found to be 1:1 and 2:2 for the complexes of L1H2 and L2H2, respectively. All the complexes are found to have octahedral geometry except [CuL1H(H2O)Cl], which exhibits a square pyramidal structure. All the complexes are nonelectrolytic in nature and the electrochemical behavior of complexes is dealt with briefly. Further ligands and complexes were evaluated for their antimicrobial activity against bacteria Escherichia coli and Pseudomonas aeruginosa and fungi Aspergillus niger and Cladosporidium.

Negative ion fab mass spectroscopy of some Ribose Alkylated 5′-ump derivatives

Characteristic fragment ions obtained in Fast atom bombardment (FAB) mass spectroscopy of ribose alkylated Uridine 5′-monophosphate (5′-UMP) derivatives in negative ion mode are described. All the compounds examined exhibited either [M]− or quasimolecular ion [M − H]− the fragmentations can be used to characterize these nucleotides.

Isolation of Peptide Components of Bacitracin by Preparative HPLC and Solid Phase Extraction (SPE)

This paper describes isolation procedure of antimicrobially active components of bacitracin (Bc) and its main oxidative degradation products needed for further stability investigations. The procedure of isolation consisted of chromatographic separation of components and degradation products, purification of isolates using solid phase extraction (SPE), and lyophilisation of pure samples. A gradient preparative HPLC separation on Kromasil 5C8 (250 × 16 mm I.D.) column was based on our previously developed analytical method, increasing the ratio of methanol against acetonitrile in the mobile phase and adjusting the flow rate, gradient profile, Bc concentration, and injection volume to achieve an efficient separation of compounds of interest under scale‐up conditions. Eluates collected after chromatographic separations were concentrated and purified using SPE procedure, simultaneously removing buffer salts derived from the mobile phase. Pure substances eluted from the SPE cartridges were then dried by lyophilisation and used for identification purposes and for further stability experiments. Identity and purity of all substances were checked and confirmed chromatographically, using diode array detection on fast monolithic silica gel Chromolith RP‐18e (100 × 4.6 mm I.D.) column after each step of the isolation procedure. Finally, the lyophilisates of active Bc components (A, B1, B2, and B3) and their corresponding oxidative degradation products (F, H1, H2, and H3) were analysed, and their identity confirmed by fast atom bombardment (FAB) mass spectrometry.

Purification and Quantitative Analysis of Destruxins from Meterhizium anisopliae by HPLC

Destruxins are metabolic toxins secreted from a fungus, Metarhizium anisopliae, during growth. The structure of destruxins has been identified as a cyclic hexadepsipeptide. Destruxins exhibit insecticidal activities. More than 35 different destruxins have been characterized to have a wide range of activity and specificity. In this report, an extraction solvent, acetonitrile, was found to yield high extraction efficiency. The fermentation broth was mixed with equal volume of acetonitrile and 5% NaCl, which formed two layers. The upper organic solvent layer, containing 80–95% of destruxins, was easily crystallized by lyophilization. The crystal could be redissolved with acetonitrile and separated by semi‐preparative HPLC. Each fraction was analyzed and identified with fast atom bombardment mass (FAB) spectrometry. The method for destruxin separation was optimized by adjusting the acetonitrile/water ratio in the gradient elution buffer of the semi‐preparative HPLC. Flatter gradient slopes may result in longer retention time and allow for higher quantity of separation. The quantitative analysis of destruxin could be achieved by generating a linear regression curve between concentrations vs. peak areas.

The interaction of AgI, ZnII and PbII with a pyridinyl-derived n5-macrocycle

The interaction of AgI, ZnII and PbII with the macrocycle L1 containing an N5-donor set has been investigated. The 1H nuclear magnetic resonance spectra of the complexes showed broad peaks, suggesting a slow exchange of metal ions between complexed and uncomplexed sites. The 1 : 1 (metal : ligand) stoichiometry was confirmed by first atom bombardment mass spectrometry and elemental microanalysis, solvent molecules being included when suggested by the infrared spectra. The X-ray crystal structures of [AgL1]ClO4, [ZnL1](ClO4)2 and [PbL1(NO3)2] have been determined. The metal atoms in complexes are endomacrocyclic with the silver atom and zinc atom in a pentacoordinate environment comprising the ligand N5-donor set. The lead atom prefers seven coordination derived from the full donor set of the macrocycle and two oxygens from dinitrate anions.

Identification of new aromatic cytokinins in Arabidopsis thaliana and Populus x canadensis leaves by LC-(+)ESI-MS and capillary liquid chromatography/frit-fast atom bombardment mass spectrometry.

A search for naturally occurring aromatic cytokinins (ARCKs) in Arabidopsis thaliana plants and Populus x canadensis leaves led to the discovery of four new plant hormone substances: 6-(2-methoxybenzylamino)purine (ortho-methoxytopolin, MeoT), 6-(3-methoxybenzylamino)purine (meta-methoxytopolin, MemT) (Fig. 1) and their 9-beta-D-ribofuranosyl derivatives. These substances were identified by liquid chromatography electrospray ionization mass spectrometry [LC (+)ESI-MS] and capillary-liquid chromatography/frit-fast atom bombardment-mass spectrometry [CapLC/frit-FAB-MS] after pre-column derivatization. The chemical structures were subsequently confirmed by chemical synthesis. Because of lack of heavy labelled internal standards, the endogenous levels of methoxytopolins in A. thaliana plants, Populus x canadensis leaves and samples derived from cultures of Agrobacterium tumefaciens strain GV3101 were determined by enzyme-linked immunosorbent assay (ELISA) of HPLC-fractionated extracts. While the levels of MeoT, MemT and their ribosides in A. thaliana shoots and Populus x canadensis leaves were relatively low (approximately 0.25-10 pmol g-1 FW for MeoT and MemT, respectively), the A. tumefaciens strain produced up to 600 times more of the newly identified substances. Cytokinin activity of methoxytopolines was demonstrated in three bioassays testing their ability to stimulate tobacco callus growth, to delay chlorophyll degradation in excised wheat leaves, and to induce betacyanin synthesis in Amaranthus caudatus var. atropurpurea cotyledons. Notably, their anti-senescing activity in the wheat leaf assay exceeded that of BAP and Z by almost 200%. Methoxytopolins are proposed to be new members of the biologically active aromatic cytokinin family, which might have specific physiological functions.

Identification and characterization of 17 phenothiazine compounds by capillary high-performance liquid chromatography/fast atom bombardment mass spectrometry

Phenothiazines are widely prescribed as neuroleptics; some are used as antihistaminics. These compounds are important in clinical and forensic toxicology. Seventeen phenothiazine compounds with heavy side chain structures have been found to be detectable by high-performance liquid chromatography/fast atom bombardment-mass spectrometry (HPLC/FAB-MS) method. Authentic samples of the compounds were subjected to our HPLC/FAB-MS system; their mass spectra were obtained by positive and negative modes. Four typical phenothiazines, in the serum samples of two patients, were also analyzed. All 17 phenothiazines were sufficiently separated on the chromatogram. In the positive mode, all the base peaks were quasimolecular ions; their main fragment ions observed were [M−R 1+CH 2] +, [R 1] +, [M−R 1] + and [M+H+Gly] +. In the negative mode, the base peaks were [Cl] − for chlorpromazine, prochlorperazine and perphenazine, three compounds containing chloride. For the other compounds, they were [M−R 1−CH 3] −, [M−R 1−CH 2CH 3] − or [M−R 1−(CH 3) 2] − ions. We observed [M+H] − ions in all the compounds, however, the ir intensities were variable (3–74%). The spectra and mass chromatograms of four compounds and their metabolites in the extracted serum samples from two patients, were also obtained. The approximate detection limits for phenothiazines were less than 1 ng on-column in the positive mode, and about 1 μg on-column in the negative mode. We have succeeded in the identification and characterization of 17 phenothiazine compounds at therapeutic concentrations in body fluids using our HPLC/FAB-MS system. The present method would be useful in forensic toxicological practice.

Analyzing the physiological signature of anabolic steroids in cattle urine using pyrolysis/metastable atom bombardment mass spectrometry and pattern recognition.

Pyrolysis coupled to metastable atom bombardment (MAB) and time-of-flight mass spectrometry (TOFMS) is used for generating mass spectra from bovine urine samples obtained from cattle treated with anabolic steroids. These spectra constitute fingerprints, which can be discriminated by multivariate statistical analysis. Four main conclusions can be drawn from this work: (i) The use of different metastable gases, such as Xe*, Kr*, or N2*, as an energy-tunable ionization beamline allows control of the internal energy and the dissociation processes of the produced odd electron molecular ions, thus giving rise to complementary mass spectra fingerprints. (ii) A variable transformation depending on the biofluid matrix suitably contracts the frequency distribution of the generated data for low m/z ratios holding information related to endogenous metabolites encountered in urine. (iii) Coupling variable selection to statistical pattern recognition methods results in low error rates (< 1%) for predicting MAB mass fingerprints, especially using lineardiscriminant analysis (LDA). (iv) LDA discriminates controls from treated animals and also correlates to quantitative physiological responses induced by anabolic steroids. This work shows that Py-MAB-TOFMS could be a suitable method for complementary monitoring anabolic use in sports, medicine, and cattle breeding, as well as monitoring many other long-lasting although weak physiological disruptions.

Sensitive determination of midazolam and identification of its two metabolites in human body fluids by column-switching capillary high-performance liquid chromatography/fast atom bombardment–mass spectrometry

Midazolam is a benzodiazepine and is widely prescribed for preanesthesia or general anesthesia. Overdose or intoxication cases of midazolam have been reported. In Japan, smuggled midazolam tablets could be involved in some criminal cases. Midazolam and its two metabolites were extracted by the solid-phase extraction method using Bond Elut SCX cartridges. The compounds were analyzed by on-line capillary high-performance liquid chromatography/fast atom bombardment–mass spectrometry. Midazolam and its two metabolites were well separated on the chromatogram, and each mass spectra gave [M+H] + ion as a base peak. Deuterium-labeled midazolam was synthesized as an internal standard; it has enabled precise and reproducible quantitation of midazolam in blood samples. The calibration curve showed excellent linearity in the range of 2–200 ng/ml in spiked serum. The detection limit was 300 pg/ml (signal-to-noise ratio=3). The whole blood and urine samples from the victim of a homicide case were analyzed, and the midazolam concentration in the whole blood was estimated to be 163 ng/ml. The present method should be useful in clinical and forensic toxicology, because of its high sensitivity and specificity.

Deuterium in vivo labelling of cytokinins in Arabidopsis thaliana analysed by capillary liquid chromatography/frit-fast atom bombardment mass spectrometry.

A method was developed for analysing the biosynthetic rate of the cytokinin class of plant hormones. Transgenic, cytokinin-overproducing Arabidopsis thaliana plants were incubated in liquid culture media enriched with 30% deuterium oxide, and incorporation into the different parts of the cytokinin molecule was analysed by capillary liquid chromatography/frit-fast atom bombardment mass spectrometry after precolumn propionylation. The sugar moieties of the cytokinins generally showed a high and independent incorporation, so the analysis in this study focused on the cytokinin base moieties. It was observed that during a 24 h incubation period almost all labelling was incorporated into the side-chain, rather than the adenine moiety. The incorporation dynamics of isopentenyladenosine-5'-monophosphate, zeatinriboside-5'-monophosphate (ZRMP) and zeatin-9-glucoside were investigated through analysis of the cytokinin base fragments in high-resolution selective ion monitoring mode. Using a fractional synthetic rate approach, the biosynthetic rate of ZRMP was determined to be 18 ng h(-1) g(-1) fresh weight, giving a turnover time of 25 h. A method for the mass isotopomer abundance analysis of the cytokinins in the zeatin family, based on selective reaction monitoring, was also developed to gain further sensitivity. Use of this technique showed that there was a higher level of enrichment in zeatin nucleotide than in the corresponding nucleoside, in agreement with the hypothesis that cytokinin nucleotides are primary products in this pathway.

Mass spectra of aminoacyl adenylate pentacoordinated phosphorus compounds

Aminoacyl adenylate pentacoordinated phosphorus compounds were analyzed by field desorption (FD) and fast atom bombardment (FAB) mass spectrometries, together with the B/E linked scan technique, and their mass spectral fragmentation pathways were investigated. For the five bonds (one P-N bond, three P-O bonds and one mixed anhydride bond P-O-CO), the cleavage usually occurred more on the P-N bond, the mixed anhydride bond and the O-C bond adjacent to the P-O bond, and less on the P-O bond. Ion YH(+), corresponding to water loss from protonated 2',3'-O-isopropylidene-adenosine, was the base peak. The results reflect the structural characteristics of aminoacyl adenylate pentacoordinated phosphorus compounds. Copyright 1999 John Wiley & Sons, Ltd.

Analysis of thermolabile and polar pesticides in environmental water with capillary chromatography-frit-fast atom bombardment mass spectrometry

Capillary LC/Frit-FAB-MS was used for the determination of 24 thermolabile and polar pesticides including 9 neutral/basic and 15 acidic ones which are not amenable to routine GC/MS. The base ions of acidic pesticides in negative mode were a deprotonated molecular ion except for asulam, MCPB, 2,4-DB, and warfarin, and those for neutral/basic pesticides and asulam in positive mode were a protonated one. More than one diagnostic ion were obtained except for hymexazol and bentazone. High sensitivity was obtained for neutral/basic pesticides and asulam by adopting a mobile phase composed of CH3CN and 0.1% acetic acid, while for the other acidic pesticides, a mobile phase composed of CH3CN and 5 mM din-butylammonium acetate (pH=6.7) was effective. The detection limits of the pesticides were in the range of 10∼300 μg/l, except for benazolin whose limit was 1000 μg/l. Environmental samples (1 L) were taken from raw water for water supply and applied to analysis after concentration by using a solid phase extraction method. 0.2 μg/l dymron (in full-scan mode) and 0.05 μ/l 2,4-D (in selected ion monitoring mode) were detected in a sample, which indicated that the LC-frit-FAB-MS method could be used for determining thermolabile and polar pesticides in environmental water with relatively high sensitivity.

Analysis of thermolabile and polar pesticides in environmental water with capillary chromatography-frit-fast atom bombardment mass spectrometry

Capillary LC/Frit-FAB-MS was used for the determination of 24 thermolabile and polar pesticides including 9 neutral/basic and 15 acidic ones which are not amenable to routine GC/MS. The base ions of acidic pesticides in negative mode were a deprotonated molecular ion except for asulam, MCPB, 2,4-DB, and warfarin, and those for neutral/basic pesticides and asulam in positive mode were a protonated one. More than one diagnostic ion were obtained except for hymexazol and bentazone. High sensitivity was obtained for neutral/basic pesticides and asulam by adopting a mobile phase composed of CH3CN and 0.1% acetic acid, while for the other acidic pesticides, a mobile phase composed of CH3CN and 5 mM din-butylammonium acetate (pH=6.7) was effective. The detection limits of the pesticides were in the range of 10–300 μg/l, except for benazolin whose limit was 1000 μg/l. Environmental samples (1 L) were taken from raw water for water supply and applied to analysis after concentration by using a solid phase extraction method. 0.2 μg/l dymron (in full-scan mode) and 0.05 μ/l 2,4-D (in selected ion monitoring mode) were detected in a sample, which indicated that the LC-frit-FAB-MS method could be used for determining thermolabile and polar pesticides in environmental water with relatively high sensitivity.