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New Scan Modes in Tandem Mass Spectrometry

R.G. Cooks
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R.G. Cooks

Résumé du colloque

Hybrid mass spectrometers, devices which use both quadrupole and sector mass analyzers, are described. The use of these instruments to obtain the parent, daughter, and neutral loss versions of MS/MS spectra is presented, as are their capabilities for analogless MS/MS experiments, variable collision energy experiments, and high sensitivity measurements. One particular configuration of the BEQQ instrument, includes four reaction regions. The availability of several reaction regions, four different types of analyzers, and two energy regimes, allows for remarkable flexibility in the MS/MS experiment. New scan modes become available by following reactions which occur in sequence in more than one reaction specific of the mass spectrometer. These new scans are more specific than the original MS/MS scan modes. For example, instead of using a scan in which loss of a neutral of mass 30 (CH2O) is used to diagnose for nitroaromatics, the fragmentation sequence (M-30-28) is substituted. This lessens contributions from false positives, e.g. methyl esters which lose 30 (CH2O), and so improves MS/MS performance in mixture analysis. Other new scans to be demonstrated are double (sequential) neutral loss scans, parent scans in which the granddaughter ion is formed, and intermediate reaction are also specified. These new experiments are shown to improve the specificity of MS/MS experiments. The use of these new scan modes is demonstrated through use of the findings of mass spectrometry, including the use of ion/molecule collisions to effect dissociations, the necessity of new parameters to classify the spectra of complex ion fragmentation, and recent progress in coupling desorption ionization methods such as SIMS to tandem mass spectrometers.

Contexte

Section :
Spectométrie de masse des années 85/90
news icon Thème du colloque :
Spectométrie de masse des années 85/90
host icon Hôte : Université du Québec à Chicoutimi

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Thème du colloque :

Spectométrie de masse des années 85/90
New Scan Modes in Tandem Mass Spectrometry
R.G. Cooks