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Mass spectrometry

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Mass spectrometry is one of my best presentation in my post graduation.

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Mass spectrometry

  1. 1. MASS SPECTROMETRY A.Solairajan, M.Pharm,1st year, S.B.C.P. 31-Aug-14 Solairajan 1
  2. 2. What is Mass Number? Zoo Zoo 31-Aug-14 Solairajan 2
  3. 3. Mass number:- The Mass number (A), also called atomic mass number or nucleon number is the total number of protons and neutrons in an atomic nucleus. No.of protons (Z) No.of neutrons (N) Mass Number (A) 31-Aug-14 Solairajan 3
  4. 4. Example:- Carbon atom have 6 protons and 6 neutrons in the centre of the nucleus, 2 electrons situated in the inner orbital where as other 4 electrons are outside the orbital. We can represent carbon atom like Mass Number(A) No. of protons(Z) Carbon Atom:- 31-Aug-14 Solairajan 4
  5. 5. 31-Aug-14 Solairajan 5
  6. 6. 31-Aug-14 Solairajan 6
  7. 7. 31-Aug-14 Solairajan 7
  8. 8. Mass spectrometry is an instrumental technique in which sample is converted to rapidly moving positive ions by electron bombardment and charged particles are separated according to their masses. Mass spectrum is a plot of relative abundance against the ratio of mass/charge(m/e). 31-Aug-14 Solairajan 8
  9. 9. 31-Aug-14 Solairajan 9
  10. 10. •To measure relative molecular masses. • To know the fragmentation of the molecules. • Comparison of mass spectra with known compounds. 31-Aug-14 Solairajan 10
  11. 11. Organic molecules are bombarded with electron converted into Highly energetic positively charged ions (Molecular ions or Parent ions) Further break up into smaller ions (Fragment ions or Daughter ions) The formed ions are separated by Deflection in Magnetic field according to their Mass and Charge MASS SPECTRUM 31-Aug-14 Solairajan 11
  12. 12. Loss of electron from a molecule leads to radical cation. e- Molecular ion 15 eV 70 eV 31-Aug-14 Solairajan 12
  13. 13.  Electron removed from molecule orbital having lowest ionization potential (IP).  In general n < π < σ Compounds Ionization potential CH4 12.6 eV C2H4 10.52 eV CH3NH2 10.3 eV 1 eV = 23 Kcal/mol 31-Aug-14 Solairajan 13
  14. 14. • Inlet system • Ion source Ionisation methods • Mass Analysers • Ion Detectors • Vacuum System 31-Aug-14 Solairajan 14
  15. 15. Inlet system 1.Solid 2.Liquid 3.Gas Mass spectrometer Ionisation ESI,EI,FAB, CI,FI,FD, MALDI,PD, TI Mass Analyser Quadrupole, TOF, Ion trap, FT-ICR Detector Photo multiplier, Electron multiplier, Faraday cup, Microchannel plate 31-Aug-14 Solairajan 15
  16. 16. 31-Aug-14 Solairajan 16
  17. 17. • SOLIDS SAMPLES with lower vapour pressure Inlet system directly inserted into the ionization chamber and volatilization is controlled by heating the probe. • LIQUIDS are handled by hypodermic needles injection through a silicon rubber dam. • GASES SAMPLES are leaked into the ionisation chamber directly by the help of mercury manometer. 31-Aug-14 Solairajan 17
  18. 18. Ionisation  The ion source is the part of the mass spectrometer that ionizes the material under analysis (the analyte).  The ions are then transported by magnetic or electric fields to the mass analyzer.  Molecular ions are formed when energy of the electron beam reaches to 10-15 eV.  Fragmentation of the ion reaches only at higher bombardment energies at 70 eV. 31-Aug-14 Solairajan 18
  19. 19. . Samples are ionised outside the ion source. This technique include, 1.Electron impact ionization (EIS) 2.Chemical ionization.(CI) 3.Field ionisation.(FI) Samples are ionised inside the ion source. This technique include, 1. Field desorption.(FD) 2. Fast atom bombardment.(FAB) Ionisation 31-Aug-314. Laser desorption.(LD) Solairajan 19
  20. 20. Ionisation 31-Aug-14 Solairajan 20
  21. 21. Electron impact ionisation Thermally volatile and stable 500 Da Chemical ionisation Thermally volatile and Stable 500 Da Electro spray ionisation Polar and Basic 70000 Da Fast atom bombardment Peptides 7000 Da Field ionisation Thermally volatile 1000 Da MALDI Large Biomolecules 3,00,000 Da Plasma desorption Neutral compounds 500 Da APCI Thermally liable 1000 Da SIMS Same as FAB 300-13000 Da Laser desorption Elemental analysis 500 Da 31-Aug-14 Solairajan 21
  22. 22. Ionisation • A beam of electrons passes through a gas-phase sample and collides with neutral analyte molecules (M) to produce a positively charged ion or a fragment ion. • Generally electrons with energies of 70 eV are used to form a fragment ions. • The positive ions are collected in focusing plates and passed to mass analyzer. 31-Aug-14 Solairajan 22
  23. 23. Ionisation 31-Aug-14 Solairajan 23
  24. 24. • The ESI source consists of a very fine needle and a series of skimmers. • A sample solution is sprayed into the source chamber to form droplets. Ionisation •When droplets carry charge exit the capillary end, as the solvent evaporates, the droplets disappear leaving highly charged analyte molecules. 31-Aug-14 Solairajan 24
  25. 25. Ionisation • Chemical Impact Ionisation between interactions of sample with large amount of reagent gas. • Commonly used reagent gases include methane,ammonia,isobutane. • Oxygen and hydrogens are used in Negative ion chemical ionisation in MS. 31-Aug-14 Solairajan 25
  26. 26. Ionisation The vaporised sample is introduced into the mass spectrometer with an excess of a reagent gas (methane) at pressure of about 1 torr. The excess carrier gas is ionized by electron impact to the primary .+ + ions CHand CH. 4 3 These may react with the excess methane to give secondary ions. 31-Aug-14 Solairajan 26
  27. 27. • In this method the molecule pass through sharp metal anode carrying an electric field of 1010 v m-1 • Electrons are analysed in primary focusing cathode slit. • ADV :- abundance of molecular ions. • DISADV :- lower resolution. Ionisation 31-Aug-14 Solairajan 27
  28. 28. Ionisation • Useful for nonvolatile and thermolabile compounds. • Sample is applied to field ion emitter and the solvent allowed to evaporate. • Evaporated sample that leads to chemical ionisation or EIS. • Example:-Nucleotides & Quarternary ammonium compounds. 31-Aug-14 Solairajan 28
  29. 29. • Argon gas ionised by hot filament and focused beam that bombards the sample. Ionisation • Beam impinges the sample, a series of molecular reactions occur and analyse in MS analyser. • Ex:-Insulin,Amino glycosides,Phospholipids. 31-Aug-14 Solairajan 29
  30. 30. Ionisation • Sample is coated with a high energetic fragment Californium 252. • This fission fragment desorbs positive,negative, and neutral molecules. • 252cf generates 1012 power at 10,000k, this may ionise the target molecule. • This method involves the interaction of laser beam with sample to produce both vaporisation and ionisation. • The vaporised sample passed to mass spectrometers for analysis. • Appl:-used for elemental analysis. 31-Aug-14 Solairajan 30
  31. 31. Ionisation  MALDI is a LIMS method of vaporizing and ionizing and sample molecules are dispersed in a solid matrix such as nicotinic acid.  A UV laser pulse ablates the matrix which carries some of the large molecules into the gas phase in an ionized form so they can be extracted into a mass spectrometer. MALDI 31-Aug-14 Solairajan 31
  32. 32. Atmospheric pressure chemical ionisation (APCI) is an analogous ionisation method to chemical ionisation(CI). Corona discharge is used to ionize the analyte in the atmospheric pressure region. Ionisation 31-Aug-14 Solairajan 32
  33. 33. Ionisation  Secondary ion mass spectrometry (SIMS) is based on the observation that charged particles (Secondary Ions) are ejected from a sample surface when bombarded by a primary beam of heavy particles.  Primary beam species useful in SIMS include Cs+, O2+, O , Ar+, and Ga+ 31-Aug-14 Solairajan 33
  34. 34. An ion, after leaving ion source, the ions are separated according to their m/e ratio. Mass Analyzer In this area, the ions are accelerated by both electrostatic and magnetically Types:- Magnetic sector mass analysers Double focussing analysers Quadrupole mass analysers Time of Flight analysers (TOF) Ion trap analyser Ion cyclotron analyser 31-Aug-14 Solairajan 34
  35. 35. m/z= H2r2/2V H Magnetic field R Radius of the curvature Mass Analyzer 31-Aug-1V4 AppliedSo lavirajoan ltage 35
  36. 36. It contains two analysers namely •Electrostatic analyser •Magnetic sector analyser. Mass Analyzer 31-Aug-14 Solairajan 36
  37. 37. Mass Analyzer The quadrupole consists of two pairs of parallel rods with applied DC and RF voltages. Ions are scanned by varying the DC/Rf quadrupole voltages. 31-Aug-14 Solairajan 37
  38. 38. Mass Analyzer 31-Aug-14 Solairajan 38
  39. 39. Mass Analyzer TOF analyzer – ions are accelerated through a flight tube and the time of fight to the detector is measured. Typical flight times are 1 to 50μs. 31-Aug-14 Solairajan 39
  40. 40. The quadrupole ion trap typically consists of a ring electrode and two hyperbolic end cap electrodes. Mass Analyzer As the radio frequency voltage is increased, the orbits of heavier ions become stabilised,and passed into the detector. 31-Aug-14 Solairajan 40
  41. 41. Mass Analyzer  Fourier transform-ICR mass spectrometry, is a type of mass analyzer for determining the mass-to-charge ratio (m/z) of ions based on the cyclotron frequency of the ions in a fixed magnetic field. The ions are trapped in a Penning trap(a magnetic field with electric trapping plates) where they are excited to a larger cyclotron radius by an oscillating electric field perpendicular to the magnetic field. 31-Aug-14 Solairajan 41
  42. 42. The excitation also results in the ions moving in phase (in a packet). The signal is detected as an image current on a pair of plates which the packet of ions passes close to as they cyclotron. The resulting signal is called a free induction decay (FID), transient or interferogram that converts signal. The useful signal is extracted from this data by performing a Fourier transform to give a mass spectrum. 31-Aug-14 Solairajan 42
  43. 43. 31-Aug-14 Solairajan 43
  44. 44. Faraday cup Electron Multiplier photomultiplier Micro Channel Plate Detector 31-Aug-14 Solairajan 44
  45. 45. Detector  The basic principle is that the incident ion strikes the dynode surface which emits electrons and induces a current which is amplified and recorded.  The dynode electrode is made of a secondary emitting material like CsSb, GaP or BeO.  It is ideally suited to isotope analysis. Faradaycup 31-Aug-14 Solairajan 45
  46. 46. Detector  Electron multipliers are the most common especially when positive and negative ions need to be detected on the same instrument.  Dynodes made up of copper-beryllium which transduces the initial ion current ,and electron emitted by first dynode are focused magnetically from dynode to the next.  Final cascade current is amplified more than million times. Electron multipliers 31-Aug-14 Solairajan 46
  47. 47. Detector  The dynode consists of a substance( a scintillator) which emits photons(light).  The emitted light is detected by photo multiplier tube and is converted into electric current.  These detectors are useful in studies on metastable ions 31-Aug-14 Solairajan 47
  48. 48. Detector 31-Aug-14 Solairajan 48
  49. 49. All mass spectrometers need a vacuum to allow ions to reach the detector without colliding with other gaseous molecules or atoms. If such collisions did occur, the instrument would suffer from reduced resolution and sensitivity. 31-Aug-14 Solairajan 49
  50. 50. TYPES OF PEAKS IN MS •Molecular ion peak •Fragment ions peak •Rearrangement ions peak •Metastable ion peaks •Multicharged ions •Base peak •Negative ion peak Molecular ion Peak:- When a sample is bombarded with electrons of 9 to 15 eV energy, the molecular ion is produced, by loss of single electron. M e- M + + 2 e - 31-Aug-14 Solairajan 50
  51. 51. Fragment ions Peak:- when an energy is given further more upto 70 eV, fragment ions produced, it have lower mass number. Rearrangement ion Peak:- Recombination of fragment ion is known as Rearrangement Peaks. Metastable ion Peak:- The ions resulting from the decomposition between the source region and magnetic analyser are called as Meta stable ions.These appear as broad peaks called Metastable ion Peaks. Multicharged ions:- Ions may exist with 2 or 3 charges instead of usual single charge.The peaks due to these charged ions are known as Multicharged ion peaks. 31-Aug-14 Solairajan 51
  52. 52. Base Peak:- The largest peak in the mass spectrum corresponding to the most abundant ion or most intense peak in the spectrum is called as Base Peak. Negative ion Peak:- Negative ions are formed from electron bombardment of sample. These results due to the capture of electron by a molecule during collision of molecules Fragment ion peak 31-Aug-14 Solairajan 52
  53. 53. FRAGMENTATION Fragmentation is a type of chemical dissociation. Fragmentation takes place by a process of heterolysis or homolysis. Types of Fragmentation:- • Collision induced dissociation(CID) • Electron capture dissociation(ECD) • Electron transfer dissociation(ETD) • Electron detachment dissociation(EDD) • Photo dissociation Infrared multiphoton dissociation(IRMPD) Blackbody infrared radiative dissociation(BIRD) • Surface induced dissociation(SID) • Charge remote fragmentation • Higher energy C-trap dissociation(HCD) 31-Aug-14 Solairajan 53
  54. 54. Collision Induced Dissociation  Molecular ions are accelerated by electrical potential to high kinetic energy and then allowed to collide with neutral molecules like He,N or Ar.  Collision between these molecules leads to bond breakage and formation of fragment ions.  These fragment ions are analysed by mass spectrometer.  Example:- Triple quadrupole spectrometer produces CID fragments. 31-Aug-14 Solairajan 54
  55. 55. SORI-CID:-(Sustained Off-Resonance Irradiation Collision-Induced Dissociation)  It is one of CID technique used in Fourier transform ion cyclotron resonance mass spectrometry.  In this method accelerating ions in cyclotron motion and increasing the pressure resulting collisions produce CID fragments. 31-Aug-14 Solairajan 55
  56. 56. Electron Capture Dissociation:-  It is a method of fragmenting gas phase ions for tandem mass spectrometric analysis (structural elucidation).  ECD involves the direct introduction of low energy electrons to trapped gas phase ions.  Electron-capture dissociation typically involves a multiply protonated molecule M interacting with a free electron to form an odd-electron ion. 31-Aug-14 Solairajan 56
  57. 57. Electron Transfer Dissociation:- ETD induces fragmentation of cations by transferring electrons to them. Example:-peptides or proteins. Electron Detachment Dissociation:- EDD is a method for fragmenting anionic species in mass spectrometry. 31-Aug-14 Solairajan 57
  58. 58. Photo Dissociation:- Photodissociation is a chemical reaction in which a chemical compound is broken down by photons. IRMPD:- Absorption of multiple infra red photons by a molecule and leads to dissociation. BIRD:- Long interaction of molecule with radiation field like carbon dioxide laser. Surface-induced dissociation:-(SID) It is a technique used in mass spectrometry to fragment molecular ions in the gas phase by collision of an ion with a surface under high vacuum. 31-Aug-14 Solairajan 58
  59. 59. Charge Remote Fragmentation:- It is a type of covalent bond breaking that occurs in a gas phase ion in which the cleaved bond is not adjacent to the location of the charge. This fragmentation can be observed using tandem mass spectrometry. Higher-energy C-trap dissociation:-(HCD) It is a fragmentation technique, used for peptide modification analysis. Immonium ions generated via HCD pinpoint modifications such as phospho tyrosine. An added octopole collision cell facilitates de novo sequencing. 31-Aug-14 Solairajan 59
  60. 60. Fragmentation of the Molecular ion Fragmentation of a molecular ion, M, produces a radical and a cation. -Only the cation is detected by MS. A-B A Radical Cation + A B B • + Molecular ion (a radical cation) + • + • + Cation Radical 31-Aug-14 Solairajan 60
  61. 61. Description of Fragmentation process:- Fragmentation of the odd electron molecular ion (M .+ ) may occur by Homolytic or Heterolytic cleavage of a single bond. 31-Aug-14 Solairajan 61
  62. 62. Mass interpretation Fragmentation rules Mclafferty rearrangement Alpha cleavage Beta cleavage Nitrogen rule Retro diels alder reaction IHD 31-Aug-14 Solairajan 62
  63. 63. Fragmentation rules:- (9 rules) Rule:-1 The height of the M .+ peak decreases with increasing degree of branching. 31-Aug-14 Solairajan 63
  64. 64. Rule:-2 The height of the M .+ Peak decreases with increasing molecular weight. Example:- Fatty molecules, steroids. 31-Aug-14 Solairajan 64
  65. 65. Rule:-3 The cleavage is favored at alkyl substituted carbons leads to formation of a carbocation. 31-Aug-14 Solairajan 65
  66. 66. Rule:-4 Double bonds, cyclic structures and aromatic rings stabilize M .+ and increase the probability of its appearance. Molecular ion peak & Base peak 31-Aug-14 Solairajan 66
  67. 67. Rule:-5 Double bonds favor allylic cleavage to give the resonance stabilized cation. 31-Aug-14 Solairajan 67
  68. 68. Rule:-6 Saturated rings tend to lose alkyl side chains at the α bond (see rule 3) Unsaturated rings can undergo a Retro-Diels-Alder reaction 31-Aug-14 Solairajan 68
  69. 69. Rule:-7 Alkyl substituted aromatic compounds are cleaved preferably at the β bond to the ring, giving the resonance stabilized benzyl ion (or) tropyllium ion. 31-Aug-14 Solairajan 69
  70. 70. Rule:-8 C-C bonds next to hetero atom are frequently cleaved, leaving the charge on the hetero atom (resonance stabilization). 31-Aug-14 Solairajan 70
  71. 71. Rule:-9 Cleavage is often associated with elimination of small stable, neutral molecules, such as CO,olefins,water,ammonia,H2S,HCN,ketene or alcohols (often with rearrangements) Ex:-Mclafferty rearrangement 31-Aug-14 Solairajan 71
  72. 72. Mclafferty Rearrangement:-  Mclafferty arrangement can occur in ketones,aldehydes,carboxylic acids, and esters.  In this rearrangement a radical center in molecular ion derived from a lone pair or pi bond, removes hydrogen from the Gamma position(γ), a pi bond is formed between the β and γ position, and the bond between the α and β positions is broken. 31-Aug-14 Solairajan 72
  73. 73. α cleavage  Alpha cleavage in mass spectrometry is a characteristic fragmentation of the molecular ion derived from carbonyl compounds, in which the bond linking the carbonyl carbon to the atom occupying an alpha position breaks. It is an expected pathway for carbonyl compounds,ethers,halides,alcohols,and amines. 31-Aug-14 Solairajan 73
  74. 74. 31-Aug-14 Solairajan 74
  75. 75. β cleavage Beta cleavage in mass spectrometry is a characteristic fragmentation of the molecular ion derived from some organic compounds, most notably alcohols, ethers, and amines, in which the bond connecting alpha- and beta-carbons break. 31-Aug-14 Solairajan 75
  76. 76. 31-Aug-14 Solairajan 76
  77. 77. Retro-Diels-Alder reactions:-  Retro Diels-Alder fragmentation occurs in 3-cyano-cyclohexene, lets first look at the fragmentation of cyclohexene.  First ionization occurs and electrons from the double bond transfer to an adjacent carbon and an electron from the bond between the 3 and 4 carbons transfers to form a second double bond that is conjugate with the first one. These rearrangements cleave the molecule between the 3 and 4 carbon and 5 and 6 (where another electron is transferred to form a double bond between the 4 and 5 carbons). This leaves an olefin and a diene. 31-Aug-14 Solairajan 77
  78. 78. 3 6 2 1 4 5 4 5 Diene Olefin 31-Aug-14 Solairajan 78
  79. 79. Nitrogen rule:- The nitrogen rule states, that a molecule that has no or even number of nitrogen atoms has an even nominal mass, whereas a molecule that has an odd number of nitrogen atoms has an odd nominal mass. Example:-1 Example:-2 31-Aug-14 Solairajan 79
  80. 80. Contd…. The molecular ion appears at m/z 121, indicating an odd number of nitrogen atoms in the structure. Odd number of molecular ion 31-Aug-14 Solairajan 80
  81. 81. IHD:-  In a hydrocarbon where all carbon atoms have only single bonds and no rings are involved, the compound would have maximum number of H atoms.  If any of the bonds are replaced with double or triple bonds, there would be deficiency of H atoms. By calculating the index of hydrogen deficiency(IHD), we can calculate molecular formula and how many multiple bonds and rings are involved. IHD is also called the Degree of Unsaturation.  A double bond and ring each counts as one IHD.  A triple bond counts as two IHD. 31-Aug-14 Solairajan 81
  82. 82. Example:-1 Example:-2 CH2=CH2 31-Aug-14 Solairajan 82
  83. 83. 31-Aug-14 Solairajan 83
  84. 84. Mass Spectrum of compounds:- Alkane:- Base Peak Molecular ion peak 31-Aug-14 Solairajan 84
  85. 85. Fragmentation of Cyclo Hexane:- C6H12 + = 84 (Molecular ion Peak), C4H8 + = 56 (Base Peak), (M-28) C6H9 + = 69 (Fragment ion Peak), (M-15) C3H7 + = 43 (Fragment ion Peak), (M-41) C2H5 + = 29 (Daughter ion Peak), CH3 + = 15 (Daughter ion Peak). 31-Aug-14 Solairajan 85
  86. 86. Alcohol Possible Fragmentations are:- Mol.wt-46 C2H5OH+ =46 (Molecular ion peak) + CHO = 31 (Base Peak) 3+ CHO = 27 (Fragment ion Peak) CH3 + = 15 (Daughter ion Peak) Base Peak Molecular ion Peak Fragment Daughter ion Peak ion Peak 31-Aug-14 Solairajan 86
  87. 87. Aldehyde:- Molecular formula:-C6H12O Molecular Weight:-100 + C6H12O = 99 (Molecular ion Peak) C3H8 + = 44 (Base Peak) C4H9 + = 57 (Fragment ion Peak) C2H5 + = 29 (Fragment ion Peak) Fragment ion Peak Base Peak- Mclafferty rearrangement Molecular ion Peak- α cleavage 31-Aug-14 Solairajan 87
  88. 88. 31-Aug-14 Solairajan 88
  89. 89. Amide:- Molecular wt :- 87, Molecular formula :- CHNO 49+ CHNO 49= 87 (Molecular ion Peak), + C2H5NO = 59 (Base Peak) Fragment ion Peak- α,β cleavage Base Peak- Mclafferty rearrangement Molecular ion Peak-β cleavage 31-Aug-14 Solairajan 89
  90. 90. 31-Aug-14 Solairajan 90
  91. 91. Amine:- Molecular wt:-59 Mol.formula :-C3H9N Base Peak-β-H transfer Molecular ion Peak- β-H transfer 31-Aug-14 Solairajan 91
  92. 92. 31-Aug-14 Solairajan 92
  93. 93. Ester Mol.wt:-102, Mol.formula:-C5H10O2 Base Peak-α cleavage Molecular ion Peak α-cleavage 31-Aug-14 Solairajan 93
  94. 94. 31-Aug-14 Solairajan 94
  95. 95. Ether Mol.wt:-130 Mol.formula:-C8H18O Base Peak-ipso cleavage α cleavage Molecular ion Peak-α cleavage 31-Aug-14 Solairajan 95
  96. 96. 31-Aug-14 Solairajan 96
  97. 97. GC-MS Gas chromatography–mass spectrometry (GC-MS) is a method that combines the features of gas-liquid chromatography and mass spectrometry to identify different substances within a test sample. Applications of GC-MS include :- Drug detection, Fire investigation, Environmental analysis, Explosives investigation, and Identification of unknown samples. 31-Aug-14 Solairajan 97
  98. 98. GC-MS 31-Aug-14 Solairajan 98
  99. 99. Tandem MS:- What is Tandem MS:- -Uses 2 (or more) mass analyzers in a single instrument. -One purifies the analyte ion from a mixture using a magnetic field. -The other analyzes fragments of the analyte ion for identification and quantification. 31-Aug-14 Solairajan 99
  100. 100. 31-Aug-14 Solairajan 100
  101. 101. Tandem mass spectrometry, also known as MS/MS or MS2, involves multiple steps of mass spectrometry selection, with some form of fragmentation occurring in between the stages. 31-Aug-14 Solairajan 101
  102. 102. Components of Tandem Mass Spectrometer MS-1 Collision cell MS-2 31-Aug-14 Solairajan 102
  103. 103. Applications of Tandem MS Biotechnology & Pharmaceutical  To determine chemical structure of drugs and drug metabolites.  Detection/quantification of impurities, drugs and their metabolites in biological fluids and tissues.  Analysis of liquid mixtures  Fingerprinting Nutraceuticals/herbal drugs/tracing source of natural products or drugs Clinical testing & Toxicology  Inborn errors of metabolism, cancer, diabetes, various poisons, drugs of abuse, etc. 31-Aug-14 Solairajan 103
  104. 104. MALDI-MS Matrix-assisted laser desorption/ionization (MALDI) is a soft ionization technique used in mass spectrometry allowing the analysis of biomolecules (biopolymers such as DNA, proteins, peptides and sugars) and large organic molecules (such as polymers, dendrimers and other macromolecules). 31-Aug-14 Solairajan 104
  105. 105.  MALDI is based on the bombardment of sample molecules with a laser light to bring about sample ionisation.  The sample is pre-mixed with a highly absorbing matrix compound for the most consistent and reliable results.  The matrix transforms the laser energy into excitation energy for the sample, which leads to sputtering of analyte and matrix ions from the surface of the mixture.  Most commercially available MALDI mass spectrometers now have a pulsed nitrogen laser of wavelength 337 nm. 31-Aug-14 Solairajan 105
  106. 106. Common matrix in MALDI Matrix Solvent Applications 2,5-dihydroxy benzoic acid Acetonitrile,water,metha nol,acetone,CHcl3 Peptides,Nucleotides, oligo nucleotides 3,5-dimethoxy-4- hydroxycinnamic acid Acetonitrile, water,acetone, CHcl3 Peptides,proteins,lipids 4-hydroxy-3- methoxycinnamic acid Acetonitrile, water, propanol Proteins Picolinic acid Ethanol Oligo nucleotides 31-Aug-14 Solairajan 106
  107. 107. 31-Aug-14 Solairajan 107
  108. 108. 31-Aug-14 Solairajan 108
  109. 109. Applications of MS:- Elucidation of the structure of the organic and biological molecules. Determination of molecular mass of peptides, proteins, and Oligonucleotides. Monitoring gases in patients breath during surgery. Identification of drugs abuse and metabolites of drugs of abuse in blood, urine, and saliva. Analyses of aerosol particles. Determination of pesticides residues in food. 31-Aug-14 Solairajan 109
  110. 110. References:- Instrumental methods of chemical analysis by willard Organic spectroscopy by William kemp Spectroscopic identification of organic compounds by Silverstein Instrumental analysis by skoog Wikipedia ww2.chemistry.gatech.edu/class/4341-6371/fahrni/set02.pdf 31-Aug-14 Solairajan 110
  111. 111. By A.Solairajan 31-Aug-14 Solairajan 111

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