Application of Linked Scanning

Linked Scanning and Metastable Ions in Magnetic-Sector Mass Spectrometry 

In a (B/E)(l - E) -scanning mode, a mass difference is seiected. For exampie, in this case a precursor ion m, is chosen (it is shown as being made up of two parts of mass mj, n,). After fragmentation, the product ion is mj accompanied by a neutral particle of mass n,. The mass difference (n, = m, - mj) can be specified so only pairs of ions connected by this difference are found. 

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MS", application of successive mass spectrometric measurements n of them), particularly in linked scanning of m/z, which is the ratio of the mass (m) of an ion and the number of charges (z) on it. Older publications used m/e, but as e is the actual charge on an electron and not the number of charges on the ion, the use of m/e was abandoned, m/z. mass-to-charge ratio, a measure of molecular mass PDB. PeeDee Belemnite (a carbon isotope standard see VPDB)... 

Millington DS, Roe CR, Maltby DA (1984) Application of high resolution fast atom bombardment and constant B/E ratio linked scanning to the identification and analysis of acylcarnitines in metabolic disease. Biomed Mass Spectrom 11 236-241... 

A special application of the peptide scan is the hybritope scan (hybrid-epitope) (44,45). In order to increase the affinity by extention of the peptide sequence in a hybritope scan, several mixtures of amino acids at positions flanking the related sequence of the protein are introduced. Another strategy to optimize a peptide scan is the so-called duotope scan (duo-epitope) (46). For a duotope scan one generates the peptide scan twice and combines the sequence of both arrays linked via a spacer, such as two -alanine molecules. In this way it is possible to avoid possible steric hindrance and to increase activity by extention of the active sequence. The pattern of such a duotope scan resembles that of a combinatorial library with the exception that each field represents a combination of two sequences rather than two amino acids. 

Another application is the differentiation of closely related isomers. The conventional mass spectra of butobarbitone and seebutobarbitone are qualitatively identical (Figs 5A and 5B). The B/E linked scans of their (M—29) ions (m/z 183) shown in Figs 5C and 5D... 

Figure 20. (A) The assembly of an integrated lactate dehydrogenase monolayer electrode by the cross-linking of an affinity complex formed between the enzyme and a PQQ-NAD monolayer-modified Au electrode. (B) Cyclic voltammograms of the integrated cross-linked PQQ-NAD / lactate dehydrogenase electrode (roughness factor ca. 15) (a) in the absence of lactate (b) with lactate, 20 mM. Recorded in 0.1 M Tris buffer, pH 8.0, in the presence of 10 mM CaCb, under Ar potential scan rate, 2 mV s . Inset amperometric responses of the integrated electrode at different concentrations of lactate upon application of potential 0.1 V vs. SCE.

These examples show the applications of MIKE method. In the same way, linked scan techniques may be particularly valuable. These methods are rapid, thus allowing the accumulation of iterative results, since there is a satisfying reproducibility. 

G. A. Warburton, A. G. Brenton, J. R. Chapman, and K. T. Taylor, Application of B/E linked scanning to structural differentiation using MS80-DS55. Kratos Data Sheet, No. 134 (1981). 

Direct MS analysis of oligomer mixtures by FAB can be combined with the Collision Induced Dissociation (CID) technique, which is used to induce the fragmentation of selected molecular ions by means of collision with an inert gas (MS/MS). This allows one to obtain daughter ions classical MS/ MS techniques utilize the linked scanning of two or more mass analyzers to obtain product (daughter) and/or precursor (parent) ion spectra see Chapters 1 and 4. Systematic application of tandem Mass Spectrometry (MS/ MS) has produced important results in the analysis of polymeric materials by FAB. " ... 

Cardiovascular Takotsubo cardiomyopathy [SEDA-33, 313] has been described after local application of adrenaline during nasal surgery in two cases cardiovascular MRI scans showed myocardial vasodilatation, capillary leak, and regional edema [1" ]. Reports linking takotsubo syndrome to the use of adrenaline during anaphylaxis have been reviewed... 

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