Rapid communications in mass spectrometry : RCM
-
Rapid Commun. Mass Spectrom. · Jan 2001
Use of matrix-assisted laser desorption/ionization time-of-flight mass mapping and nanospray liquid chromatography/electrospray ionization tandem mass spectrometry sequence tag analysis for high sensitivity identification of yeast proteins separated by two-dimensional gel electrophoresis.
Current analytical techniques in protein identification by mass spectrometry are based on the generation of peptide mass maps or sequence tags that are idiotypic for the protein sequence. This work reports on the development of the use of mass spectrometric methods for protein identification in research on metabolic pathways of a genetically modified strain of the baker's yeast Saccharomyces cerevisiae. This study describes the use of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass mapping and liquid chromatography/quadrupole time-of-flight electrospray ionization tandem mass spectrometry (LC/Q-TOF-ESI-MS/MS) sequence tag analysis in identification of yeast proteins separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). ⋯ Mass mapping as a rapid, high-throughput method was in most cases sensitive enough for identification. LC/MS/MS was found to be more sensitive and to provide more accurate data, and was very useful when analyzing small amounts of sample. Even one sequence tag acquired by this method could be enough for unambiguous identification, and, in the present case, successfully identified a point mutation.
-
Rapid Commun. Mass Spectrom. · Jan 2001
On-line measurement of the absolute humidity of air, breath and liquid headspace samples by selected ion flow tube mass spectrometry.
We describe how selected ion flow tube mass spectrometry (SIFT-MS) can be used to determine the absolute humidity of air, breath and liquid headspace samples. This involves the determination of the relative count rates of the H3O+ ions and those H3O+.(H2O)(1,2,3) hydrate ions that inevitably form in the helium carrier gas when humid samples are being analysed by SIFT-MS using H3O+ precursor ions. ⋯ Thus, we show that the humidity of breath and liquid headspace samples, typically at the few percent level, can be directly obtained on-line to the SIFT-MS instrument along with the concentrations of trace gases, which are present at much lower levels. We emphasise the value of parallel humidity measurements in ensuring good real-time sampling of breath and liquid headspace and the value of such measurements to trace gas analysis using SIFT-MS.
-
Rapid Commun. Mass Spectrom. · Jan 2000
Quantification of hydrogen sulphide in humid air by selected ion flow tube mass spectrometry.
We report the results of a study of the reactions of H(3)O(+), NO(+) and O(2)(+.) ions with H(2)S. This study was undertaken to provide a thorough understanding of the ion chemistry required for accurate quantification of H(2)S in humid air by selected ion flow tube mass spectrometry (SIFT-MS). It shows that slow reactions occur between H(3)S(+), the primary product ions of the H(3)O(+)/H(2)S reaction, and the abundant H(2)O molecules present in humid air and breath. ⋯ This study also shows that NO(+) does not react with H(2)S, and that O(2)(+.) does react rapidly with H(2)S, but the product H(2)S(+.) ions react rapidly with H(2)O. Thus, NO(+) and O(2)(+.) cannot be used as precursor ion for analysis of H(2)S in moist air by SIFT-MS. A sample SIFT mass spectrum is shown from which H(2)S and several other volatile compounds have been quantified in a sample of cow rumen gas.
-
Rapid Commun. Mass Spectrom. · Jan 2000
Influence of water vapour on selected ion flow tube mass spectrometric analyses of trace gases in humid air and breath.
Selected ion flow tube mass spectrometry (SIFT-MS) detects and quantifies in real time the trace gases, M, in air/breath samples introduced directly into a flow tube. Inevitably, relatively large partial pressures of water vapour are introduced with the sample and the water molecules become involved in the ion chemistry on which this analytical technique depends. When H(3)O(+) ions are used as the precursors for chemical ionisation and SIFT mass spectrometric analyses of M, they generally result in the formation of MH(+) ions. ⋯ Additionally, some fundamental data have been obtained on the association reactions of protonated organic molecules, MH(+) ions, with water molecules forming MH(+). H(2)O monohydrate ions. For some types of M, reaction sequences occur that lead to the formation of dihydrate and trihydrate ions.
-
Rapid Commun. Mass Spectrom. · Jan 1999
The use of capillary high performance liquid chromatography with electrospray mass spectrometry for the analysis of small volume blood samples from serially bled mice to determine the pharmacokinetics of early discovery compounds.
The methodology described demonstrates, for the first time, the feasibility of performing pharmacokinetic studies in the serially bled mouse model to support the early development of discovery compounds. Sample analysis, using capillary high performance liquid chromatography combined with tandem mass spectrometry, has facilitated the achievement of this milestone and has successfully been applied to determine pharmacokinetic information following both intravenous and oral administration of a single discovery compound. The methodologies described demonstrate potential for a reduction in the amount of new chemical entity required to undertake pharmacokinetic studies. ⋯ The use of capillary high performance liquid chromatography (HPLC) has facilitated the analysis of small volume blood samples by increasing the effective sensitivity of the analytical method. Consequently, we have established a protocol for serially bleeding mice thus reducing the number of animals and so further reducing the amount of compound required for such experiments. This paper reports data obtained from collected and processed blood volumes of <20 microL with the subsequent injection of only 1 microL of precipitated extract onto a capillary column.