The Role of Multiple MS Technologies in Bioanalytical Analysis

Transcription

1 The Role of Multiple MS Technologies in Bioanalytical Analysis Daniel Pentek* February 3, UCONN Bioanalytical Chem 395

2 Introduction Dan Pentek Education: Wesleyan University: Bachelor s and Master s in Chemistry UCONN: Masters in Business Administration Work Experience: Yale University Chemical Instrumentation Center ( 83-93) Mass Spectrometrist Perkin-Elmer / Sciex Joint Venture ( 93-99) LCMS Instructor Product Specialist (demos, applications, etc.) Technology Sales Manager Application/ Demo/ Training Lab Manager Bayer Healthcare Pharmaceuticals ( 99-04) (99- Sr Scientist Principle Scientist Automation and New Technology PerkinElmer, Inc ( 04- present) MS Technology Manager, Product Owner, Product Manager, etc. 2

3 Topics to be covered: Introduction ti Bioanalytical Overview MS - MS Market & Technologies Basic ionization methods Electrospray, APCI, APPI Interfaces Orifice, capillary MS Analyzers Performance Criteria Strengths & weaknesses for bioanalytical analyses Quadrupole (single &triple quads) Ion traps (3-D and 2-D) Time of flight (linear, reflectron, MALDI) Hybrids (Quad-TOF) and others FTMS (ICRs and orbitraps)

4 Block Diagram - Bioanalytical Analysis Sample Preparation Sample Separation Sample Analysis Data Analysis S a m p l e T h r o u g h p u t SPEED is the driver!! Eliminate bottlenecks! MS provided a paradigm shift in these areas 4

5 Separation Based on Mass Has Been Around a Long Time Winnowing is a mass separation technique. 5 Slide from Dr. Athula Attygalle

6 Modern Grain Mill Separation Based on Mass A modern grain mill does this more efficiently. In fact, each process taking place inside a grain mill can be compared to those taking place inside a mass spectrometer 6 Slide from Dr. Athula Attygalle

7 What is a (Modern) Mass Spectrometer? An instrument that separates molecules or atoms (e.g., ICP/MS) based on their mass/charge ratio (m/z). m is the mass ΙzΙ is the absolute value of the number of charges on it. Mass is reported in u, mass units, or the unified atomic mass unit which is defined as 1/12 th the mass of carbon 12 ( 12 C) or Da (Daltons) which is more prevalent in the biochemistry world. Prior to 1993, mass was reported in atomic mass units (amu) which was defined as 1/16 th the mass of oxygen 16 ( 16 O). Masses are still frequently reported in amu, but this is incorrect! An MS provides 2 dimensions i of information: A signal that something is there (a signal intensity) The mass of what is there, to a nominal or very precise level of accuracy

8 LC/MS Historical Perspective Industry was desperate for a decent, rugged LC/MS interface. GC/MS required derivatization, etc. Not applicable to most biomolecules (MW, etc.) Atmospheric pressure ionization (API) ionization along with new interface designs provided the solution. Now, all interfaces are differentially pumped. Pumping of interfaces was critical Orifice skimmer (nozzle) designs Heated (or cold) capillary designs LC/MS is a big business now!

9 Analytical Instruments Technology Segments SDI data on analytical instrument technology shows mass spectrometry is a $2.6B market in 2010, and predicts that it will have fastest growth rate (8.6%) of any analytical instrument technology through 2014 *SDI Global 11 th Ed. Sept. 2010

10 Distribution of Mass Spectrometry Techniques* * Avg. CGR >10% Growth Opportunities $101M $255M $643M $312M $139M $136M $391M CGR 2.3% CGR 6.2% CGR 9.5% CGR 9.4% CGR 17.0% CGR 9.7% CGR 4.9% $61M $241M PKI has product offerings CGR 3.8% CGR 7.2% *SDI Global 9 th Ed. Sept. 2006

11 LC/MS(/MS): A Marriage of Liquid Chromatography and Mass Spectrometry Marriage (like any other close relationship) requires: COMPROMISE! LC Person: MS is just another detector MS Person: LC is just an inlet What s good for LC may not be good for MS and vice versa. LC was around a long time before they figured out how to interface it to an MS.

12 LC/MS Instrument Block Diagram LC Eluant Ion Source Interface Mass Analyzers Detectors -ESI -Orifice Sk -Quadrupole -CEM -APCI -Capillary -Ion Trap (4 types) -Discrete dynode -APPI (Hot or cold) -Time of Flight -CCD -Photomultiplier MS System under vacuum

13 Today s LC/MS Ionization Methods: All Done at Atmospheric Pressure On-line techniques: Electrospray (ESI) - Yale ~1984 Shared Nobel Prize in 2002 for this work with K. Tanaka (MALDI) and K. Wüthrich (NMR) Atmospheric Pressure Chemical Ionization (APCI) Irabarne & Thomson ~1979 Atmospheric Pressure Photo Ionization (APPI) Emerging, not as widely used yet. All of the above are done at atmospheric pressure Significant ifi change from traditional ionization i methods which h were all done within the vacuum chamber. Off-line techniques: Matrix Assisted Laser Desorption Ionization (MALDI) Desorption Electrospray (DESI) DART- Direct analysis in real time and more

14 PerkinElmer Acquires Analytica of Branford In ~June of 2009, PKI acquired Analytica of Branford, Inc. (AoB) AoB was company started by John Fenn (share Nobel Prize 2002) and Craig Whitehouse (who built first electrospray source on an LCMS) John Fenn Craig Whitehouse (Nobel Prize Lecture 2002) Company held exclusive IP on electrospray and multiple charging of molecules In 1987 AoB started designing ESI sources for many vendors Developed early ESI-TOF MS Developed over 75 patents in the field of MS Ion source technology Ion guide technology Coupling ESI to o-tof MS

15 Significant Overlap in Ionization Techniques 1000 kda Molecula ar Weigh ht 100 kda 10 kda Peptides Electrospray Proteins 1 kda Carbamates 100 Da APPI PAHs Steroids APCI Phenyl ureas Low 15 Polarity High

16 Electrospray- Spraying a Very (Charged) Fine Mist High pressure nebulizer gas provides pneumatic assistance 16

17 Electrospray: Ion Evaporation Process for LC/MS Desolvation Process and Ionization Mechanism Rayleigh limit is the maximum charge a droplet can hold while maintaining its volume Evaporation Rayleigh Coulombic Limit Explosions Reached Ions Ejected Droplet Capillary How well this works depends on the mobile phase composition and flow rate. Must have proper probe positioning, CCDG flow and CCDG temperature and nebulizer pressure to insure proper ionization of analyte ion. 17

18 Electrospray: Ion Evaporation Process for LC/MS Electric field lines Heated drying gas (drawing (+) ions in toward (-) charge) Droplet from sprayer with (+) and (-) charges on it - 2. Droplet shrinks with mobile phase evaporation 3. Coulombic repulsions rupture droplet ejecting ions (with solvent molecules) 4. Ions of desired polarity follow field lines to capillary tip while being stripped of residual solvent by heated drying gas and they are sucked into the MS entrance V at MS entrance (under vacuum)

19 Electrospray ESI is most widely used LCMS ionization technique Electrospray is a concentration dependent technique. Ease of use and LC flow rates drove source development. Started out as very low flow technique, which wasn t very compatible with LC. LC Person: Use lower flows and narrower column. MS Person: Buy ESI probe that has higher gas flows and desolvates better. Nanospray takes ESI to much lower flow rates Preserves precious sample Allows multiple MS experiments to be run over time (which takes time)

20 Bio ana Example of Ion Source Designed for High LC Flow (AB-Sciex).

21 Electrospray- Tips Modifiers Organic acids (e.g. formic, acetic) promote ionization of basic compounds (sp 3 N- containing) i Neutral compounds containing nucleophilic lone pairs (sp 2 N, sp 3 O) can be desorbed by cationization with alkali metal or ammonium ions. Ammonium formate or acetate are recommended buffers ( 2-10 mm optimum, can see suppression effects over 20 mm, 50 mm max.) Salts can interfere with ionization and can cluster to complicate spectrum (but also aid in identification) Strong bases or quaternary amines can interfere with positive mode analytes Sulfonic acids interfere with negative mode analytes AVOID PHOSPHATE BUFFERS as much as possible Contaminate ion path Suppress ionization

22 Atmospheric Pressure Chemical Ionization (APCI) Conventional APCI Source Configuration Field Free APCI Source Sample Inlet Nebulization Gas Inlet Auxiliary Gas Inlet Nebulizer Sample Inlet Nebulization Gas Inlet Auxiliary Gas Inlet Nebulizer Heater Heater Gas Curtain Electrode Hot N 2 Gas Curtain Electrode Corona Needle To MS Corona Analyzer Needle Sampling Capillary Increased analyte concentration around corona needle. Decoupling of Ion production from Ion Transport Field. Hot N 2 To MS Analyzer Sampling Capillary CONFIDENTIAL AND PROPRIETARY INFORMATION OF PERKINELMER, INC 2009 Perkin Elmer

23 APCI Reactions N 2 + e - N e - N H 2 O H 2 O +. + N 2 H 2 O +. + H 2 O H 3 O + + OH. H + + [M+H] + 3 O M + H 2 O

24 APCI- Summary HN is a high flow ( ml/min.) inlet Suitable for polar, thermally stable cmpds Usually, MW < 1000 amu Probe is heated to facilitate vaporization Requires nebulizing and auxiliary gas Requires corona discharge needle to produce ionization (APCI)

25 Atmospheric Pressure Photo Ionization (APPI) Emerging technique (about 5 years old) Uses typical 10 ev UV lamp p( (similar to photo-ionization lamps for GC). Similar to APCI, but applicable to broader range of compounds.

26 LC/MS Instrument Block Diagram LC Eluant Ion Source Interface Mass Analyzers Detectors -ESI -Orifice Sk -Quadrupole -CEM -APCI -Capillary -Ion Trap (4 types) -Discrete dynode -APPI (Hot or cold) -Time of Flight -CCD -Photomultiplier MS System under vacuum

27 Example: Orifice-Skimmer Interface (AB-Sciex) Nitrogen Gas Curtain Interface Differentially Pumped Interface A PI ION SOURCE + Cu ur tain GasFlow Orifice Plate QØ Skimmer VACUUM CHAM MBER Bio ana

28 Flexar SQ 300 MS Detector Ion Optics and Vacuum System Heated Countercurrent Drying Gas (N2) Dielectric Capillary 4 stage pumping system: 30/200/200 cartridge turbo with E2M28 rough pump Patented ion guide technology traversing multiple vacuum stages

29 Vacuum Interface: Protective Gas & Differentially Pumped Interfaces Regardless of interface used; UHP nitrogen counter current drying (CCDG) gas keeps non-ionized species out of the analyzer region CCDG aids in ion de-clustering (with CID potentials) Two stage transition from atmosphere to low pressure region of analyzer (1 x 10-5 torr) CCDG and ions are drawn in due to; Pressure differential (both ions & CG) Electric field gradients (ions only) Interface exit into vacuum offers sample fragmentation opportunity Poor man s MS/MS

30 1 st Vacuum Region- Supersonic Expansion Occurs (Mach Disk) Within a Mach disk, all ions and gas molecules moving in same direction It should project into the skimmer zone for ion transmission Capillary ID, skimmer ID and pumping speed are all variables requiring optimization CID induced by voltage difference between cap. exit and SK

31 LC/MS Instrument Block Diagram LC Eluant Ion Source Interface Mass Analyzers Detectors -ESI -Orifice Sk -Quadrupole -CEM -APCI -Capillary -Time of Flight -Discrete dynode -APPI (Hot or cold) (MALDI- TOF) -CCD -Ion Trap (4 types) -Photomultiplier MS System under vacuum

32 Analyzer (and System) Criteria Analyzer Considerations: Mass accuracy Resolution Sensitivity Scan speed Dynamic range System Considerations: Sensitivity Sample thru-put Fast LC? Primary application: quantitation, qualitative or Software- application based Ease of use!!! Price

33 Single MS vs.ms/ms Systems: Single MS systems (quadrupole or TOF) Have the added dimension of mass vs. UV or diode array detectors. However, chemical noise is the limiting factor for sensitivity (S/N) and dynamic range. So sample preparation becomes a bigger factor! MS/MS Systems Many variations now Triple Quads - 2 quadrupole MS s s, separated by a collision cell QTOFs - Quadrupole front end, collision cell, TOF back end MS n analyzers- ion traps (3D and 2D) and FTMS s TOF-TOF, separated by collision cell IT TOF (Shimadzu) Purposes essentially the same (regardless of analyzer type), select one ion from all the others, fragment it, and study the fragment ions MS/MS systems ARE the paradigm shift in bioanalytical analysis

34 Mass Accuracy- Mass Analyzer Comparison (LC/MS) Cost: ~ ($M) m/z = Quadrupole ppm Ion Trap ppm Time of Flight 1-20 ppm FTMS-ICR ppm FTMS IT (Orbitrap) ppm

35 Resolution- What is it? Ability to separate (resolve) adjacent ions Typically defined as: M/ M M: Mass M: Full Width at Half Max. Quadrupoles: scan at constant peak width 30/1=30, 300/1=300, 3000/1=3000 Resolution increases as you go to higher mass TOFs: scan at constant resolution 10k res: m/z , , , 10,001 Peak width increases as you go to higher mass

36 Analyzer Types: Quadrupoles (and hexapoles, octopoles, etc.) Fundamental parts of virtually all LC/MS systems Serve one of two purposes: Ion transmission devices (quad, hex, oct ) Capture and transmit ions from one place to another Ion filtering devices (quadrupoles only ) Act as a mass filter (analogous to a magnetic)

37 Quadrupole Theory Quad. as a mass filter Separates ions based on m/z ratio Voltages applied determine width of mass window Quad. made of 4 rods A pole - vertical rods; B pole y L horiz. rods (by convention) DC, RF volt. imposed: + r o + r x U=(DC) A -(DC) B (FDC) z V: RF volt. peak-peak (RF p-p ) V = 7.22 * M * r 02 * f 2 ; i.e., V ~ M

38 Time-of-Flight (TOF) Analyzers TOF Analyzer Linear Mode Reflectron Mode Common Ionization Methods for TOF MS MALDI ESI

39 TOF Ion Optics (Linear) 39 t = time taken to reach the detector (seconds) m = mass of the ion (kg) z = number of charges on the ion. If singly charged z = 1 e = magnitude of the charge of an electron (coulombs) V = Accelerating voltage (volts) d = distance an ion travels (flight tube) (meters) Limitations: Kinetic energy distribution

40 Basic API TOF MS Ion Flight Path Detector Pulsing Region Hexapole Ion Guide Horizontal TOF Drift Tube Dielectric Capillary Ion Mirror Grounded API Source 40 CONFIDENTIAL AND PROPRIETARY INFORMATION OF PERKINELMER, INC 2009 Perkin Elmer

41 Trap-Pulse Mode, Small Packet of Ions Ions filling ion guide, storing ions from last pulse, ion guide exit high High m/z Bias +30V +10V 0V Each ion packet smaller than usable pulsing region, mini TOF Bias +30V +10V 0V Low m/z 0V 0V 0V 0V Over fill region ions lost Initial ion release from ion guide, ion guide exit low High m/z Low m/z Bias -30V +10V 0V Pulser voltage applied, ions accelerated for TOF 0V Bias +30V +10V 0V +400V High m/z Exclusion region ions lost Short pulse of ions from ion guide, ion guide exit high, start storing for next pulse High m/z Low m/z Bias +30V +10V 0V 0V Low m/z +200V 0V Usable pulsing region 0V Slide #: CONFIDENTIAL AND PROPRIETARY INFORMATION OF PERKINELMER, INC 2009 Perkin Elmer

42 MALDI Mass Spectrometry MALDI = Matrix-Assisted Laser Desorption / Ionization c ass Spec Ma

43 MALDI-TOF Ex. Data

44 Sample Applications (TOF MS) Biomarker Discovery

45

46 MS/MS Systems: Triple Quadrupole OR IQ1 RNG IQ2 CEM Q0 ST RO1 ST3 RO3 DF RO2 (LINAC) 1 Torr S25B Pump 6 mtorr Varian 550 Leybold 361 Backed by D10E

47 Triple Quad Scanning Modes: Multiple reaction Monitoring (MRM) TQ s remain the Gold Standard for quantitation because of MRM If Q1 and Q3 width=0, then MRM Many (hundreds!) of precursor to product ion pairs can be monitored (A-B, A -B, A B A -B, etc.) MRM analysis is the best way to maximize signal intensity of product ions

48 MS/MS - Multiple Reaction Monitoring (MRM) Precursor ion set Fragmentation (CAD) Product ion set

49 MS/MS Systems: Quadrupole-TOF (QTOF) Introduced commercially by Micromass around Brilliant innovation, first commercial hybrid MS/MS. They charged what the market would bear $ k No competition! Great qualitative analyzer TOF analyzer provided: Incredibly fast scan rates Accurate mass capability (MW confirmation) Higher resolution (8k initially, now 10-12k w/ 1 reflectron)

50 QSTAR XL System Schematics 770 L/s 250 L/s DC Quad 4-anode detector Accelerator column Sample Ions Q0 2.5 Torr Curtain Gas 10-2 Torr Q1 LINAC eliminate cross-talk fast switching MS MS 2 broad dynamic range saturation correction Q2 10 mtorr 770 L/s Effective Flight Path = 2.5 m Field Free Drift region 7x10-7 Torr Conducting liner Ion Mirror (reflector)

51 Micromass QTOF Premier

52 What can a QTOF do for you?

53 4 Types of Ion Traps

54 Analyzer Types: Ion Traps -MS/MS n Systems 3D Ion Trap

55 3D Ion Trap- MS/MS Operation

56 Triple Quads vs. Ion Traps Complementary MS/MS Approaches: Tandem in Space: Triple Quads Poor scanning sensitivity Great for quant (MRM) Very selective scans Tandem-in-Time: Ti Ion Traps Very sensitive scanning Only product ion scans Only scanning capability

57 Ion Traps -2D (2002) Ion bottles for optical spectroscopy. Minimize fringing fields to maximize performance. Ion accumulation for enhanced ms sensitivity. High quality mass spectrometer: t RCM, 2002, 16, Linear Traps 3-D DTraps Feb. 1, 2007

58 AB-Sciex Q TRAP System Ion Path Skimmer N 2 CAD Gas Dipolar Aux AC Q0 Q1 Q2 Q3 Oifi Orifice IQ1 IQ2 IQ3 Exit LINAC linear ion trap 3-4x10-5 Torr

59 Trapping Forces in a Linear Ion Trap Radial Trapping RF Voltage Axial Trapping DC Voltage Axial Trapping Radial Trapping RF Voltage Resonance Excitation Exit Lens

60 Linear vs. 3-D Ion Traps: Linear Trap Trapping Efficiency No quadrupole field on center line. Longer flight path. 3-D Trap Trapping Efficiency Quadrupole field gives amplitude and phase dependent injection eff s. ~1 cm to lose injection energy. Extraction Efficiency 18-20% (measured) Ion Capacity: Linear trap is ~10X Extraction better Efficiency < 50% (Probably ~30%) 3-D trap is ~2X Ion better Capacity: 5-inch linear trap: 45X greater capacity

61 MS n Systems: FTMS Ion Trap- Orbitrap Finnigan LTQ Orbitrap FTMS Feb. 1, 2007

62 Finnigan LTQ Orbitrap FTMS

63 Orbitrap (Brochure) Data

64 MS n Systems: FTMS (ICR) w/2d Ion Trap Front End

65 Thermo FTMS (ICR) Feb. 1, 2007

66 FTMS Data Example

67 ABI-4800 TOF-TOF

68 3D Ion Trap - TOF New Hybrid Design Shimadzu LCMS IT-TOF

69 Summary Role and importance of MS in bioanalytical analysis continues to grow and evolve MS is typically no longer the bottleneck (sample handling and data acquisition/processing slow thru-put) Power of new MS technology providing new dimension of information on biomolecules There are 3 fundamental MS analyzer technologies, each with it s advantages and disadvantages. Hybrids can take advantage of best of 2 technologies LC/MS continues to evolve at a rapid rate Better, faster, cheaper