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The role of fast atom bombardment mass spectroscopy (FABMS) in cluster characterization

Sotelo,Adriana F.; Felicissimo,Anna Maria P.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2005 EN
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66.26%
Fast atom bombardment mass spectroscopy has been used to study a large number of cationic phosphine-containing transition-metal-gold clusters, which ranged in mass from 1000 to 4000. Many of these clusters have been previously characterized and were examined in order to test the usefulness of the FABMS technique. Results showed that FABMS is excellent in giving the correct molecular formula and when combined with NMR, IR, and microanalysis gave a reliable characterization for cationic clusters¹. Recently FABMS has become one of the techniques employed as routine in cluster characterization2,3 and also is an effective tool for the structure analysis of large biomolecules4. Some results in the present work reinforce the importance of these data in the characterization of clusters in the absence of crystals with quality for X-ray analysis.

Glycosphingolipid antigens from Leishmania (L.) amazonensis amastigotes: Binding of anti-glycosphingolipid monoclonal antibodies in vitro and in vivo

Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/1997 EN
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66.26%
Specific glycosphingolipid antigens of Leishmania (L.) amazonensis amastigotes reactive with the monoclonal antibodies (MoAbs) ST-3, ST-4 and ST-5 were isolated, and their structure was partially elucidated by negative ion fast atom bombardment mass spectrometry. The glycan moieties of five antigens presented linear sequences of hexoses and N-acetylhexosamines ranging from four to six sugar residues, and the ceramide moieties were found to be composed by a sphingosine d18:1 and fatty acids 24:1 or 16:0. Affinities of the three monoclonal antibodies to amastigote glycosphingolipid antigens were also analyzed by ELISA. MoAb ST-3 reacted equally well with all glycosphingolipid antigens tested, whereas ST-4 and ST-5 presented higher affinities to glycosphingolipids with longer carbohydrate chains, with five or more sugar units (slow migrating bands on HPTLC). Macrophages isolated from footpad lesions of BALB/c mice infected with Leishmania (L.) amazonensis were incubated with MoAb ST-3 and, by indirect immunofluorescence, labeling was only detected on the parasite, whereas no fluorescence was observed on the surface of the infected macrophages, indicating that these glycosphingolipid antigens are not acquired from the host cell but synthesized by the amastigote. Intravenous administration of 125I-labeled ST-3 antibody to infected BALB/c mice showed that MoAb ST-3 accumulated significantly in the footpad lesions in comparison to blood and other tissues

Disulfide linkages in the in vitro refolded intermediates of recombinant human macrophage-colony-stimulating factor: analysis of the sulfhydryl alkylation of free cysteine residues by fast-atom bombardment mass spectrometry.

Glocker, M O; Arbogast, B; Milley, R; Cowgill, C; Deinzer, M L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 21/06/1994 EN
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66.44%
Fast-atom bombardment mass spectrometry was used to follow the time course of disulfide bond formation during in vitro refolding of recombinant human macrophage-colony-stimulating factor. The content of iodoacetamide-alkylated half-cystines in proteolytic peptides of trapped refolding intermediates collected at 0, 6, 17, 24, and 72 hr was determined under reducing conditions. Size-exclusion high-performance liquid chromatography analyses of the collected alkylated samples indicate that aggregated monomer proceeded through a nonaggregated monomer to an intermediate dimer and finally to the fully folded and active dimer. Underalkylation was first detected by fast-atom bombardment mass spectrometry in 17-hr samples at Cys157 and Cys159 and this corresponded to the first sample containing dimer. Analyses of intermediates from subsequent time points indicated a decrease in alkylated sulfhydryls, and at 72 hr no alkylated peptide was detected. Early samples containing only monomer showed no evidence of disulfide bonds, and the occurrence of disulfide shuffling at the monomer stage could be ruled out under the highly reducing conditions used for refolding. Biological activity was not detectable in early samples but increased to 3.6% after 24 hr of refolding and to 86% of maximum at the 72-hr time point.

On-line analysis of penicillin blood levels in the live rat by combined microdialysis/fast-atom bombardment mass spectrometry.

Caprioli, R M; Lin, S N
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1990 EN
Relevância na Pesquisa
66.44%
The combination of microdialysis and fast-atom bombardment mass spectrometry has been used to follow the pharmacokinetics of penicillin G directly in the blood-stream of a live rat. After the intramuscular injection of the antibiotic, the blood dialysate was allowed to flow into the mass spectrometer via the continuous-flow/fast-atom bombardment interface. Tandem mass spectrometry provided the means for isolating and recording the ion fragments produced from the drug as the dialysate was exposed to the ionization process. The pharmacokinetic results obtained are compared with those previously reported in the literature, and this on-line method is discussed in terms of its particular advantages.

Characterization of acetylated and acetolyzed glycoprotein high-mannose core oligosaccharides by fast-atom-bombardment mass spectrometry.

Tsai, P K; Dell, A; Ballou, C E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1986 EN
Relevância na Pesquisa
66.26%
Fast-atom-bombardment mass spectrometry has been applied to acetylated neutral and phosphorylated oligosaccharides from yeast glycoproteins and to their acetolysis products. Although acetylation increases the sample molecular weight and the complexity of the spectra, it also enhances the sensitivity of detection, is applicable to samples that contain salt, and is especially useful for analysis of phosphorylated derivatives. Acetylation by trifluoroacetic anhydride/glacial acetic acid is particularly convenient and can be done rapidly on a small amount of material. Acetolysis by acetic anhydride/glacial acetic acid/H2SO4 is done on the acetylated oligosaccharides, and the acetylated fragments are recovered by solvent extraction and immediately subjected to mass spectrometry. The methodology allows molecular weight determinations and sequence analysis by acetolysis to be carried out on a few micrograms of isolated oligosaccharide in a few hours.

Isolation of a human myocardial cytosolic phospholipase A2 isoform. Fast atom bombardment mass spectroscopic and reverse-phase high pressure liquid chromatography identification of choline and ethanolamine glycerophospholipid substrates.

Hazen, S L; Hall, C R; Ford, D A; Gross, R W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1993 EN
Relevância na Pesquisa
66.26%
Recent studies have demonstrated the existence of a novel family of calcium-independent plasmalogen-selective phospholipases A2 in canine myocardium that have been implicated as enzymic mediators of ischemic membrane damage. We now report that human myocardium contains two functionally distinct isoforms of cytosolic calcium-independent phospholipase A2. The major cytosolic phospholipase A2 isoform preferentially hydrolyzes plasmalogen substrate, possesses a pH optimum of 7.0, and is chromatographically resolvable from a minor cytosolic calcium-independent phospholipase A2 isoform that hydrolyzes plasmenylcholine and phosphatidylcholine substrates at similar rates and possesses a pH optimum of 8.5. The major cytosolic calcium-independent phospholipase A2 isoform was identified as a 40-kD polypeptide after its 182,000-fold purification by sequential column chromatographies to a final specific activity of 67 mumol/mg.min. The purified 40-kD human myocardial phospholipase A2 preferentially hydrolyzes plasmalogens containing arachidonic acid at the sn-2 position. Both reverse-phase HPLC and fast atom bombardment mass spectroscopic analysis of human myocardial ethanolamine and choline glycerophospholipids demonstrated that plasmenylethanolamine and plasmenylcholine molecular species containing arachidonic acid at the sn-2 position are prominent constituents of human myocardium. Collectively...

Determination of Betaines by Fast Atom Bombardment Mass Spectrometry 1: Identification of Glycine Betaine Deficient Genotypes of Zea mays

Rhodes, David; Rich, Patrick J.; Myers, Ann C.; Reuter, Carol C.; Jamieson, Gene C.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1987 EN
Relevância na Pesquisa
66.26%
A rapid, sensitive, and selective method for the determination of betaines is described and discussed. The method entails derivatizing the quaternary ammonium compounds to increase their sensitivity to detection by fast atom bombardment mass spectrometry. Sensitivity of detection increases markedly as the length of the carbon chain of the alcohol used to esterify the betaine carboxylic acid group is increased (C4 > C3 > C2 > C1 > C0). The lower limit of detection of glycine betaine as the n-propyl ester is 0.05 nanomole per microliter of glycerol. Betaine aldehyde can be readily derivatized to the di-n-butyl or di-n-propyl acetal derivatives which exhibit lower limits of detection of about 5 picomoles and 10 picomoles per microliter of glycerol, respectively. Accurate quantification of these compounds is accomplished by the use of deuterium labeled internal standards or quaternary ammonium compound homologs of distinct mass. Methods for the synthesis of these internal standards are reported. Some applications of these methods are illustrated with stable isotope tracer studies on the kinetics of metabolism of choline to betaine aldehyde and glycine betaine in spinach leaf discs, and the identification of several Zea mays genotypes which appear deficient in glycine betaine. Tracer studies with deuterium labeled betaine aldehyde suggest that the deficiency of glycine betaine in one sweet corn hybrid is probably not due to a deficiency in the capacity to oxidize betaine aldehyde.

Betaines of Alfalfa 1: Characterization by Fast Atom Bombardment and Desorption Chemical Ionization Mass Spectrometry

Wood, Karl V.; Stringham, Kelly J.; Smith, David L.; Volenec, Jeffrey J.; Hendershot, Kerry L.; Jackson, Kimberly A.; Rich, Patrick J.; Yang, Wen-Ju; Rhodes, David
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1991 EN
Relevância na Pesquisa
66.26%
Leaf tissue of alfalfa (Medicago sativa L.) was found to contain prolinebetaine, pipecolatebetaine, hydroxyprolinebetaine, and glycinebetaine. As n-butyl esters, these chemical species exhibit molecular cations at mass/charge ratio (m/z) 200, 214, 216, and 174, respectively, when analyzed by fast atom bombardment mass spectrometry. The underivatized betaines exhibit protonated molecular ions at m/z 144, 158, 160, and 118, respectively, when analyzed by desorption chemical ionization mass spectrometry. Extensive (>45-fold) genotypic variation for hydroxyprolinebetaine level was identified in alfalfa. Because a significant inverse correlation between prolinebetaine and hydroxyprolinebetaine levels was observed among 15 alfalfa genotypes evaluated, it is possible that these compounds may be derived from a common intermediate. Birdsfoot trefoil (Lotus corniculatus L.) contained prolinebetaine, but only traces of glycinebetaine, pipecolatebetaine, and hydroxyprolinebetaine. Red clover (Trifolium pratense L.) lacked prolinebetaine, pipecolatebetaine, and hydroxyprolinebetaine, but contained appreciable levels of both glycinebetaine and trigonelline. Trigonelline was not detectable in the leaf tissue of any alfalfa genotype or cultivar evaluated.

Purification and characterization by fast-atom-bombardment mass spectrometry of the polymorphonuclear-leucocyte-elastase-generated A alpha (1-21) fragment of fibrinogen from human blood after incubation with calcium ionophore A23187.

Dewey, R S; Liesch, J M; Williams, H R; Sugg, E E; Dolan, C A; Davies, P; Mumford, R A; Albers-Schönberg, G
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/01/1992 EN
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66.26%
The stimulation of human blood with a Ca2+ ionophore, A23187, leads to activation of polymorphonuclear leucocytes (PMN) with release of small amounts of catalyticaly active elastase, as demonstrated by the formation of a characteristic product, the N-terminal A alpha (1-21) peptide of the Aa subunit of fibrinogen. The identity of the peptide was initially established by radioimmunoassay (r.i.a.) with an antibody raised to A alpha (1-21). We now provide independent confirmation of the formation of A alpha (1-21) by fast-atom-bombardment-m.s. analysis of the fractions separated chromatographically after spiking of plasma samples with peptide labelled with [2H8]Phe at position 8. Identity of the peptides was established on the basis of their chromatographic retention time and by the distinct peaks in the mass spectra of these fractions. The relative intensities of the molecular ions of natural and labelled peptides were measured. On the basis of a comparison of the peaks of similar intensities, the concentration of the natural peptide at the time of spiking was close (79%) to the amount obtained by r.i.a. An additional peptide, des-alanyl-A alpha (2-21), was also seen. The total amount of material measured by r.i.a. could be accounted for by the sum of these two provides. The addition of label and assay by m.s. has provided an independent physical-chemical method for identifying A alpha (1-21) as a characteristic product of PMN elastase release in whole blood...

Peptide sequencing by using a combination of partial acid hydrolysis and fast-atom-bombardment mass spectrometry.

De Angelis, F; Botta, M; Ceccarelli, S; Nicoletti, R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/06/1986 EN
Relevância na Pesquisa
66.26%
To overcome the limit of the intensity of ions carrying sequence information in structural determinations of peptides by fast-atom-bombardment m.s., we have developed a method that consists in taking spectra of the peptide acid hydrolysates at different hydrolysis times. Peaks correspond to the oligomers arising from the peptide partial hydrolysis. The sequence can then be identified from the structurally overlapping fragments.

Identification by fast atom bombardment mass spectrometry of insulin fragments produced by insulin proteinase.

Savoy, L A; Jones, R M; Pochon, S; Davies, J G; Muir, A V; Offord, R E; Rose, K
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/01/1988 EN
Relevância na Pesquisa
66.26%
We describe the isolation by reversed-phase h.p.l.c. of a number of products of the degradation of insulin by insulin proteinase and their direct analysis by fast atom bombardment mass spectrometry (f.a.b.-m.s.). Various semisynthetically labelled insulins were used, including [[2H2]GlyA1]insulin and [18O]LysB29]insulin. The results obtained confirm and extend the results obtained by non-mass-spectrometric methods [Davies, Muir, Rose & Offord (1988) Biochem. J. 249, 209-214, and papers cited therein]. Cleavage sites were identified between positions A13-A14, A14-A15, B9-B10, B13-B14, B24-B25 and B25-B26. The advantages and disadvantages of the application of f.a.b.-m.s. to such studies are discussed.

Formaldehyde adducts of glutathione. Structure elucidation by two-dimensional n.m.r. spectroscopy and fast-atom-bombardment tandem mass spectrometry.

Naylor, S; Mason, R P; Sanders, J K; Williams, D H; Moneti, G
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/01/1988 EN
Relevância na Pesquisa
66.26%
Aqueous mixtures of formaldehyde and glutathione react to form a variety of cyclized adducts in addition to S-hydroxymethylglutathione. The adducts are in labile equilibrium with each other and are not readily separated. The structures of two of the other major adducts were determined by concerted application of 13C-1H two-dimensional chemical-shift correlation, fast-atom-bombardment mass spectrometry and tandem mass spectrometry to the adduct mixtures in aqueous solution.

C-terminal peptide identification by fast atom bombardment mass spectrometry.

Rose, K; Savoy, L A; Simona, M G; Offord, R E; Wingfield, P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/02/1988 EN
Relevância na Pesquisa
66.26%
A previously described technique [Rose, Simona, Offord, Prior, Otto & Thatcher (1983) Biochem. J. 215, 273-277] permits the identification of the C-terminal peptide of a protein as the only peptide that does not incorporate any 18O upon partial enzymic hydrolysis in 18O-labelled water. Formation of chemical derivatives followed by combined g.l.c.-m.s. was used in this earlier work. We now describe the isolation from protein digests, by reversed-phase h.p.l.c., of labelled and unlabelled polypeptides and their direct analysis by fast atom bombardment mass spectrometry. Under the conditions used, the 18O label is retained throughout the separation and analysis, thus permitting assignments of C-terminal peptides to be made. Enzyme-catalysed exchange of label into the terminal carboxy group was found to occur in some cases without hydrolysis of a peptide bond. This effect, which may be exploited to prepare labelled peptides, does not prevent application of the method (two separate digests must then be used). We have applied our method to the analysis of enzymic partial hydrolysates of glucagon, insulin and of several proteins produced by expression of recombinant DNA.

Structure of two sulphated oligosaccharides from respiratory mucins of a patient suffering from cystic fibrosis. A fast-atom-bombardment m.s. and 1H-n.m.r. spectroscopic study.

Lamblin, G; Rahmoune, H; Wieruszeski, J M; Lhermitte, M; Strecker, G; Roussel, P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/04/1991 EN
Relevância na Pesquisa
66.26%
Human respiratory-mucin glycopeptides were isolated from the sputum of a patient suffering from cystic fibrosis. They were subjected to treatment with alkaline borohydride. Application of ion-exchange chromatography afforded carbohydrate fractions containing sulphate. One of these fractions containing a mixture of sulphated oligosaccharides was subsequently submitted to gel-filtration chromatography and h.p.l.c. Two sulphated oligosaccharide-alditols, A and B, were prepared; their structure was determined by means of 400 MHz 1H-n.m.r. spectroscopy and fast-atom-bombardment m.s. They had a core type 2 and the sulphate was 3-linked to a terminal galactose residue: (Formula; see text)

Fast-atom-bombardment mass spectrometry and electron-impact direct-probe mass spectrometry in the structural analysis of oligosaccharides with special reference to the poly(N-acetyl-lactosamine) series.

Hounsell, E F; Madigan, M J; Lawson, A M
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/05/1984 EN
Relevância na Pesquisa
66.26%
A comparison has been made of positive- and negative-ion fast-atom-bombardment (FAB) and electron-impact (EI) mass spectrometry for analysis of oligosaccharides and alditols containing alternating and consecutive sequences of neutral and acetamido sugars. Among these were novel chemically synthesized tetrasaccharides with Ii antigen activities. FAB ionization has the advantage that it is applicable to non-derivatized oligosaccharides and it can determine Mr. However, the abundance of fragment ions providing structural information and the amount of material required for analysis (1-50 nmol) varied from sample to sample. In contrast, EI mass spectrometry of 5 nmol of permethylated or peracetylated oligosaccharides reliably gives all the fragment ions formed by cleavage across the glycosidic bonds.

Fast-atom-bombardment mass spectra of enkephalins.

Barber, M; Bordoli, R S; Garner, G V; Gordon, D B; Sedgwick, R D; Tetler, L W; Tyler, A N
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/08/1981 EN
Relevância na Pesquisa
66.44%
The positive- and negative-ion mass spectra of [methionine]enkephalin and [leucine]enkephalin have been obtained by using a fast-atom-bombardment source described previously by Barber, Bordoli, Sedgwick & Tyler [(1981) J. Chem. Soc. Chem. Commun., in the press]. This technique has allowed the spectra to be obtained without conversion of the enkephalins into volatile derivatives. The fast-atom-bombardment spectra show good pseudo-molecular-ion sensitivity and fragmentation that can be interpreted on the basis of the known molecular structure.

Fast-atom-bombardment mass spectrometry. A new technique for the determination of molecular weights and amino acid sequences of peptides.

Williams, D H; Bradley, C V; Santikarn, S; Bojesen, G
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/01/1982 EN
Relevância na Pesquisa
66.26%
A detailed study of the mass spectra of peptides produced by the new technique of fast-atom bombardment is reported. Molecular weights of unmodified peptides containing up to 21 amino acids have been determined. In favourable cases, the molecular-weight determination may be made on as little as 0.1 nmol of sample. Positive-ion and negative-ion spectra are obtained with equal facility. With sample sizes in the range 2-50nmol, sequence information can be obtained in many cases. The technique represents an important contribution to structural studies on peptides, since (i) blocked peptides may be studied, (ii) no prior formation of chemical derivatives is necessary (except for distinction between lysine and glutamine), (iii) sensitivity is good, (iv) large peptides, and, in some cases, mixtures of peptides, can be studied, and (v) the technique is easy to operate, with ions being produced over a long period (5-30 min).

A fast atom bombardment mass spectrometry study of tris (3, 6-dioxaheptyl) amine-alkali metal halide complexes and hydrogen bonded complexes

Théberge, Roger.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
ENG
Relevância na Pesquisa
66.44%
The objective of this thesis was to demonstrate the potential of fast atom bombardment mass spectrometry (FABMS) as a probe of condensed phase systems and its possible uses for the study of hydrogen bonding. FABMS was used to study three different systems. The first study was aimed at investigating the selectivity of the ligand tris(3,6-dioxaheptyl) amine (tdoha) for the alkali metal cations. FABMS results correlated well with infrared and nmr data. Systems where a crown ether competed with tdoha for a given alkali metal cation were also investigated by fast atom bombardment. The results were found to correlate with the cation affinity of tdoha and the ability of the crown ether to bind the cation. In the second and third studies, H-bonded systems were investigated. The imidazole-electron donor complexes were investigated and FABMS results showed the expected H-bond strength of the respective complexes. The effects of concentration, liquid matrix, water content, deuterium exchange, and pre-ionization of the complex were also investigated. In the third system investigated, the abundance of the diphenyl sulfone-ammonium salt complexes (presumably H-bonded) in the FABMS spectrum were found to correlate with qualitative considerations such as steric hindrance and strength of ion pairs.

Comparative electron impact and fast atom bombardment mass spectrometric studies of some HMPA adducts of phenyltin and phenyllead halides and studies of strong hydrogen bonding by FAB-MS

Mondal, Humayun.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
ENG
Relevância na Pesquisa
66.26%
The fragmentation patterns and mass spectra of some phenyl tin and -lead halide adducts with hexamethylphosphoramide are compared by subjecting them t~ electron impact and fast atom bombardment ionization in a mass spectrometer. This comparison is restricted to the metal-containing ions. Ligand-exchange mechanisms of some of the metal-containing species are explored by FAB-MS. Several moisturesensitive organo-metallics and H-bonded systems have been examined by FAB for attempted characterization, but without any success. Scavenging and trapping of water molecules by complex aggregates in solutions of quaternary ammonium fluorides and hydroxides are investigated by FAB to complement previous NMR-studies.

Fast atom bombardment mass spectrometry studies of ruthenium (II) polypyridy coordination complexes and of group V Triptycenes and related complexes

Nye, Jeffrey W.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
ENG
Relevância na Pesquisa
66.31%
In order to investigate the use of Fast Atom Bombardment Mass Spectrometry (FAB-MS) as a tool for structural characterization, two groups of complexes are analyzed. The first group is a set of ruthenium(II) coordination complexes containing bidentate polypyridyl ligands. The positive and negative ion FAB-MS spectra are found to be sufficient to allow for an almost complete characterization of the central metal atom, the ligands and the counter anions contained in the intact complex. An unusual observation of mUltiply charged ions in the positive ion FAB-MS spectra (i.e. [RUL 3 ]2+) is explained to be as a result of the oxidative quenching of the excited state of the doubly charged ion by the matrix, 3-nitrobenzyl alcohol. An analysis of a mixture shows that the technique is a good one for identifying components therein. A group of triptycene and related complexes containing Group V elements is also analyzed by FAB-MS and the results. in terms of relative abundances of fragment ions, are found to be consistent with known metal-carbon bond strengths.