137 results about "Electron ionization" patented technology
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Electron ionization (EI, formerly known as electron impact ionization and electron bombardment ionization) is an ionization method in which energetic electrons interact with solid or gas phase atoms or molecules to produce ions. EI was one of the first ionization techniques developed for mass spectrometry. However, this method is still a popular ionization technique. This technique is considered a hard (high fragmentation) ionization method, since it uses highly energetic electrons to produce ions. This leads to extensive fragmentation, which can be helpful for structure determination of unknown compounds. EI is the most useful for organic compounds which have a molecular weight below 600. Also, several other thermally stable and volatile compounds in solid, liquid and gas states can be detected with the use of this technique when coupled with various separation methods.
The invention provides a mass spectrometric method for analyzing a sample in a solution, including the steps of directing a flow of a solution containing sample compounds to be analyzed towards a supersonic nozzle having an input end and an output end; vaporizing the solution and sample prior to its expansion from the output end of said supersonic nozzle; allowing expansion of the vaporized sample and solution from said supersonic nozzle into a vacuum system, forming a supersonic molecular beam with vibrationally cold sample molecules; ionizing the vaporized sample compounds with electrons while contained as vibrationally cold molecules in said supersonic molecular beam; mass analyzing the ions formed from said sample compounds; detecting said ions formed from said sample compounds after mass analysis, and processing the data obtained from the resulting mass spectral information, for identifying and / or quantifying the chemical content of said sample. The invention also provides apparatus for analyzing a sample in a solution.
Electrosprayionization sources interfaced to mass spectrometers have become widely used tools in analytical applications. Processes occurring in Electrospray (ES) ionization generally include the addition or removal of a charged species such as H+ or other cation to effect ionization of a sample species. Electrospray includes ionization processes that occur in the liquid and gas phase and in both phases ionization processes require a source or sink for such charged species. Electrolyte species, that aid in oxidation or reduction reactions occurring in Electrospray ionization, are added to sample solutions in many analytical applications to increase the ionsignal amplitude generated in Electrospray and detected by a massspectrometer (MS) Electrolyte species that may be required to enhance an upstream sample preparation or separation process may be less compatible with the downstream ES processes and cause reduction in MS signal. New Electrolytes have been found that increase positive and negative polarity analyteionsignal measured in ESMS analysis when compared with analyte ESMS signal achieved using more conventional electrolytes. The new electrolyte species increase ES MS signal when added directly to a sample solution or when added to a second solution flow in an Electrospray membrane probe. It has also been found that running the ES membrane probe with specific Electrolytes in the second solution of the ES membrane probe have been found to enhance ESMS signal compared to using the same electrolytes directly in the sample solution being Electrosprayed. The new electrolytes can be added to a reagention source configured in a combination Atmospheric pressureion source to improve ionization efficiency.