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Protein Chemistry Lab
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    • Amino Acid Analysis
      • Amino Acid Codes
      • AAA Assay Description
      • AAA Instrumentation
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    • Protein Sequence Analysis
      • Edman Experimental Procedure
    • Mass Spectrometry
      • Protein/Peptide Mass Determination
        • MS Mass Instrumentation
        • MS Mass Sample Preparation
        • Procedure for MALDI-TOF Analysis
        • Procedure for Electrospray Mass Analysis
        • Accuracy of the Analysis
      • Protein Identification-Proteomics
        • MS Protein ID Instrumentation
        • Sample Preparation and Purity
        • PMF/PSD
        • LC/MS/MS
        • Accuracy of the Analysis
        • In-gel Digestion of Proteins
    • Electrophoresis
      • SDS-Polyacrylamide Gel Electrophoresis
      • 2 Dimensional Gel Electrophoresis
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      • Chromatography Instrumentation
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    • Amino Acid Analysis
    • Protein Sequence Analysis
    • Protein/Pectide Mass Determination
    • Protein Identification/Proteomics
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    • Gayan Nawaratna, Ph.D.
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Procedure for Electrospray Mass Analysis

The ThermoScientific Exactive Orbitrap uses electrospray as an ionization source. Samples may be infused into the instrument using a syringe or applied directly into the instrument from an in-line HPLC system that separates peptides using reversed phase chromatography. Sample preparation is much more critical for this method than for MALDI-TOF mass spectrometry. It is very sensitive to sample media. Therefore, samples for infusion should be prepared in water, if possible, or in acetonitrile or methanol. Although tolerated at very low levels, trifluoroacetic acid is discouraged as an ion-pairing agent. Formic acid is suggested in its place. Please contact us for further information concerning sample preparation, amount and concentration electrospray mass spectrometry.

Typically, peptides below 2000 daltons are amenable to this technique. Proteins above 2000 daltons can be analyzed but with reduced success due to our lack of adequated deconvolution software. Proteins must be exquisitely free of salts, detergents and other contaminants to have any chance of success by this approach. MALDI-TOF mass spec is better suited to larger proteins.

  • MS Mass Instrumentation
  • MALDI-TOF Procedure
  • Electrospray Procedure
  • Accuracy
  • Sample Preparation
  • Submittal Form
  • Protein/Peptide Mass Determination
    • Accuracy of the Analysis
    • MS Mass Instrumentation
    • MS Mass Sample Preparation
    • Procedure for Electrospray Mass Analysis
    • Procedure for MALDI-TOF Analysis
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