Maldi tof mass spectrometry ppt

Maldi tof mass spectrometry ppt

• 1.
  MALDI- TOF MASS SPECTROMETRY BYJWALA 1st MSc MARINE MICROBIOLOGY
• 2.
  INTRODUCTION  MALDI isa soft ionization technique that strikes large molecules with laser energy into minimal ion fragments.  MALDI stands for Matrix- Assisted Laser Desorption Ionization.  TOF stands for Time of Flight.  This technology generates characteristic mass spectral fingerprints which are compared with large library of mass spectra. As the spectral fingerprints are unique signatures for each microorganism, accurate microbial identification at the genus and species levels is done using bioinformatics pattern profiling.
• 3.
  MALDI-TOF MASS SPECTROMETER
• 4.
  WORKING PRINCIPLE FORMALDI- TOF SPECTROMETRY The MALDI-TOF process is a two-phase procedure;  Ionization Phase  Time of flight phase The second phase is the time-of-flight mass spectrometry phase. It has two modes:- linear mode and reflector mode.
• 5.
  METHODOLOGY  First, theanalyte should be dissolved in a solvent making up to 0.1mg/ml and the matrix should be dissolved with a saturated or concentrated solution of about 10mg/ml. Both the solution is then mixed together in 1000:1 to 100,000:1 ratio.  The mixture is placed on a metal target plate which crystallizes on drying and forms a solid deposit. Then the mixture is transferred into the MALDI – TOF instrument for analysis.
• 6.
   Sublimation andionization separate the ions depending upon the size and charge ratio through a TOF analyzer which is operated on the MS software.  To increase the ability in identifying gram-positive and sugar non fermenting bacterial species, formic acid is used with the preparatory extraction of microbes whereas gram- negative bacteria can be identified using direct cell profiling.
• 7.
  The process ofmass spectrometry
• 8.
  Target plate
• 9.
  APPLICATIONS OF MALDI- TOFMASS SPECTROMETRY  Biochemistry  Peptide mass fingerprinting (PMF)  Clinical and environmetal bacteriology  Detection of viruses  Organic chemistry  Medicine
• 10.
  ADVANTAGES  Significantly decreasesthe turnaround time. Processing time is similar to rapid bio-chemicals.  The sample preparation is simple and the sample requirement is minimal. A single colony is sufficient in order to generate spectra of sufficient quality  Cost effective-low consumable costs
• 11.
   Automated, robust,inter-laboratory reproducibility  Broad applicability (all types of bacteria including anaerobes, fungi)  Adaptable-open system, expandable by user.
• 12.
  DISADVANTAGES  Identification ofnew isolates is possible only if the spectral database contains peptide mass fingerprints of the type strains of specific genera/species/subspecies/strains  No susceptibility information is provided  Not useful for direct testing of clinical specimens (except urine)
• 13.
   Some organismsrequire repeat analysis and additional processing (extraction)  The acceptable score cut-offs vary between studies and some closely related organisms are not differentiated.  Some organisms currently cannot be reliably identified by this method, such as Shigella spp and Streptococcus pneumoniae.
• 14.
  REFERENCES  en.wikipedia.org/wiki/Matrix- assisted_laser_desorption/ionization  ModernExperimental Biochemistry. Rodney F Boyer. Benjamin/Cummings publishing company Inc. Redwoodcity, California.  thesciencenotes.com/maldi-tof-mass-spectrometry-principle- methodology-and-applications/