Universitéde Montreal

Other

University of Montreal

Michel J Bertrand

Olivier Peraldi

Andre L'heureux

Denis Faubert

Dimo Zidarov

The metastable atom bombardment source provides a charged particle free beam of metastable species that can be used to bombard and ionize organic and inorganic substances in a gas phase. The metastable atoms are produced by inducing a discharge in a gas (rare gases or small molecules). The discharge is curved between the cathode and anode, with the cathode located in a medium pressure zone and the anode located off-axis in a low pressure zone. A nozzle located between the cathode and the anode provides a collimated beam of metastable atoms of low kinetic energy that is directed at an ion volume containing the substances to be analyzed. By selecting the energy of the metastable state, selective fragmentation of molecules, particularly large molecular weight molecules, can be carried out.

Metastable atom bombardment source

For analyzing micro-organisms and other high-molecular weight species, a sample of the substance to be analyzed is prepared, placed in a pyrolyzer where it is pyrolyzed with a selected temperature program to provide pyrolyzed product of a high-dalton mass range. The product is ionized using metastable atoms which results in efficient ionization with little fragmentation. The metastable atoms are generated using a generator that provides a beam of metastable atoms which is basically free from ions. The ionized product is then analyzed using a high acquisition rate mass analyzer, such as a time-of-flight (TOF) analyzer.

Time-of-flight bacteria analyser using metastable source ionization

A method of processing data representing intensity values of a measurement signal as a function of a discrete variable such as time, which signal being characterized by series of peaks mixed with a substantially regular background noise, provides efficient noise attenuation and peak detection capabilities. When applied to a two-dimensional system, the method comprises an initial step of forming an intensity histogram vector representing a frequency distribution from the intensity values, which intensity histogram vector having N frequency vector components associated with corresponding N intensity sub-ranges within a maximum range extending from a minimum intensity value to a maximum intensity value. This initial step is followed by a step of zeroing a portion of the data corresponding to the intensity values which are below an intensity threshold value derived from shape characteristics of the distribution. Then, the intensity threshold value is subtracted from each remaining portion of the data to obtain processed data representing the measurement signal in which each peak exhibits an enhanced signal-to-noise ratio. The method is also applicable to multi-dimensional measurement systems involving more than one variable, such as chromatography/mass spectrometry measurement techniques.

Measurement signal processing method

A flow of a carrier gas through a column is provided. A sample is provided in the column, and a temperature of a longitudinally short portion of the column is raised to a predetermined controlled high temperature at which volatile substances are released from the sample packing and are carried by the carrier gas. The column is cooled on each side of the short portion to a low temperature at which the volatile substances condense or adsorb on the column packing. By continuously moving the heated short portion from an inlet end to an outlet end of the packing in a direction of carrier gas flow the volatile substances selected by the controlled high temperature are released. Four particularly useful and advantageous applications can be identified for the invention. Firstly, it provides an improved gas chromatograph (GC) injector. Secondly, it provides an improved thermal separator or extractor. Thirdly, it provides an efficient way to analyze target compounds suspected of being contained within a complex mixture by allowing for the GC analysis to be carried out only on those compounds or substances falling within the same or similar thermal desorption characteristics as those of the target compound. Lastly, by operating in a full time-coupled time-resolved (TCRC) mode, a complete three-dimensional analysis output can be obtained giving better power of separation of the analyzed sample, which is of particular importance when the substance to be analyzed is a complex organic material.

Selective removal of volatile substances injected into a chromatographic packing filled column

Selective removal of volatile substances injected into a chromatographic

The metastable atom bombardment source provides a charged particle free beam of metastable species that can be used to bombard and ionize organic and inorganic substances in a gas phase. The metastable atoms are produced by inducing a discharge in a gas (rare gases or small molecules). The discharge is curved between the cathode and anode, with the cathode located in a medium pressure zone and the anode located off-axis in a low pressure zone; A nozzle located between the cathode and the anode provides a collimated beam of metastable atoms of low kinetic energy that is directed at an ion volume containing the substances to be analyzed.

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Verdun, Canada

Michel J Bertrand