Rapid Communications in Mass Spectrometry

doi: 10.1002/rcm.1290061010pmid: N/A

doi: 10.1002/rcm.1290061001pmid: N/A

Pucci, Sergio; Raffaeli, Andrea; Lazzaroni, Raffaello; Salvadori, Piero

doi: 10.1002/rcm.1290061002pmid: N/A

This paper describes a simple and cheap home‐made cryofocusing device useful in thermal desorption/gas chromatography/mass spectrometry (GC/MS) to achive the refocusing of the substances desorbed, in order to us use different flow rates during the desorption time (higher flow rate) and the GC/MC analysis (lower flow rate). Some preliminary results of the qualitative and quantitave determinatino of organic pollutants present in air are also presented. The combinatin used, comprising dynamic adsorption/thermal desorption/cryofocusing/GC/MS, allowed us to reach detection limits in the upper ng/m3 (that is, the upper part‐per‐trillion range) per single component.

Curcuruto, O.; Tarzia, G.; Hamdan, M.

doi: 10.1002/rcm.1290061003pmid: N/A

A number of commercially available purine derivatives were investigated by means of chemical ionization in ammonia and methane reagent gases. The protonated molecules of the compounds investigated were mass selected and their collision‐induced dissociated (CID) spectra monitored using 100 eV collision energy. Competition between the protonation and addition reaction channels which yield MH+ and [M + NH4]+ ions and the major fragment ions observed in the CID spectra reflect certain stereochemical differences between the isomeric precusors investigated. The present work is an attempt to contribute to the continuous search for first and effective means of distinguishing between the various isomers of biomedically important classes of compounds.

Newton, Russell P.; Khan, Jalal A.; Brenton, A. Gareth; Langridge, James I.; Harris, Frank M.; Walton, Terence J.

doi: 10.1002/rcm.1290061004pmid: 1330090

A protein kinase, stimulated by cytidine 3′, 5′ ‐cyclic monophosphate, is conventionally assayed by monitoring the incorporation of radiolabelled phosphate from adenosine triphosphate into a histone substrate. Here the assay of the protein kinase is carried out by positive‐ion fast‐atom bombardment mass spectrometric analysis of the enzyme incubation mixture after the reaction has been terminated. The data so obtained show good agreement with data obtained by the conventional radiometric assay: the intrinsic advantage of the mass spectrometric assay is the capacity for multiple component monitoring; the ability of the kinase to bind competing cyclic nucleotides togeter with integral adenosine triphosphatase (ATPase) and phosphodiesterase activity can also be assessed.

Monaghan, J. J.; Morden, W. E.; Johnson, T.; Wilson, I. D.; Martin, P.

doi: 10.1002/rcm.1290061005pmid: N/A

The results of thin layer chromatography/mass spectrometry (TLC/MS) and thin layer chromatography/tandem mass spectrometry (TLC/MS/MS) experiments are described. Spectra from the analytes were obtained directly from the absorbent without the need for extraction prior to analysis by mass spectrometry. These results illustrate the added specificity that the tandem mass spectrometer can afford in the detection and characterization of a range of compounds separated by TLC.

Cole, Richard B.; Domelsmith, Linda N.; David, Connie M.; Laine, Roger A.; DeLucca, Anthony J.; Promé, J. C.

doi: 10.1002/rcm.1290061006pmid: 1421514

Endotoxins from gram‐negative bacteria are believed to be causative agents of byssinosis, an occupational pulmonary disease associated with exposure to cotton dust in textile mills. Lipid A preparations from Enerobacter agglomerans, a gram‐negative bacterium commonly found in cotton and cotton dust, have been analyzed using plasma‐desorption mass spectrometry. Results indicate the existence of at least two lipid A types which differ only by the presence of an additional oxygen atom whose position has been localized to the acyloxyacyl ester‐linked side‐chain of the distal portion of the molecule. The lower molecular weight compound of the two structures has the same molecular weight and presumably the same empirical formula as a well‐characterized lipid A from Salmonella minnesota. The mass spectra of lipid A compounds obtained from S. minnesota and E. agglomerans show strong similarities. Palmitoyl, hydroxymyristoyl, myristoyl, and lauroyl side‐chains which are known to be prest in the former are inferred from spectral evidence to be present in the latter.

Tu, Ya‐Ping; Chen, Yao‐Zu

doi: 10.1002/rcm.1290061007pmid: N/A

The reactions between aliphatic acids and alcohols in the gas phase were investigated by chemical ionization (CL) mass spectrometry. The association of the acylium ion of acids with alcohols is suggested as an esterificaion mechanism under CI conditions in addition to the classical nucleophilic addition—elimination pathway.

Dinya, Zoltán; Lipták, Miklós; Lévai, Albert; Tóth, Gábor; Vékey, Károly

doi: 10.1002/rcm.1290061008pmid: N/A

The positive‐ion electron impact mass spectra of twelve spiro‐1‐pyrazolines have been recorded as 70 eV electron energy and the dat analyzed to elucidate their fragmentation pathways. None of these compounds gave abundant molecular ions (M+) due to the instability of the pyrazoline ring. The first step in the decomposition of M+ ions is the elimination of a nitrogen molecule followed by a rearrangement resulting in the formation of the cation radical [M–28]+, the decomposition of which is discussed in detail. The proposed fragmentation pathways and their mechanisms are supported by high‐resolution data, linked‐scan measurements at constant B/E and collision‐induced dissociation‐mass‐analyzed ion kinetic energy spectra.

Schieltz, David M.; Chou, Chau‐Wen; Luo, Cong‐Wen; Thomas, Robert M.; Williams, Peter; Becker, C. H.

doi: 10.1002/rcm.1290061009pmid: 1421515

We report time‐of‐fight mass spectra of test mixtures of six single‐stranded DNA segments. The segments range in size from 8 to 60 nucleotides (molecular weight range 2413 to 18 602 Da). The best mass spectra were obtained by pulsed laser ablation of thin frozen films of an aqueous solution of the mixture from an oxidized copper substrate. These mass spectra are dominated by the molecular‐ion peak for each DNA segment, and show little evidence of fragmentation, peak broadening or cluster formation. In contrast, mass spectra obtained using UV laser ablation from an anthranilic acid matrix yield broad peaks with evidence of fragmentation, and DNA segments longer than 26 nucleotides are difficult to detect.