MOMA: Mars Organic Molecule Analyzer Luann Becker Johns Hopkins Physics and Astronomy Harsh Environment Mass Spectrometry Workshop September 23rd

Transcription

1 MOMA: Mars Organic Molecule Analyzer Luann Becker Johns Hopkins Physics and Astronomy Harsh Environment Mass Spectrometry Workshop September 23rd 2009

2 Strategy for Future Missions to Mars - Lessons learned from Past Rover/Lander Missions: Emphasis on Life Detection - Present Missions: Looking Ahead to the Next Decade - New Instrument Concepts in Search for Life: MOMA 2

3 Mission Timeline MSL Lander Discovery Mid Rover Mission NASA Joint Missions NASA/ESA ExoMars 3

4 Earth and Mars Today 4

5 Map of Mars showing H2O and Landing Sites P 5

6 Previous Mass Spectrometry Concepts High mass range à complex organic analysis Drill to 2m; depth profiling Multiple sampling modes 6

7 Viking Missions: What Happened? Viking (1976) GCMS: Surface soil No organics found by GCMS Nutrient Experiment Inconclusive Conclusions: Highly oxidizing soil, low ph (acidic), ionizing radiation produce non-volatile organic salts resulting in more refractory labile organic material 1 Benner et al., (2000) The Missing Organic Molecules on Mars? PNAS Kminek G and Bada JL (2006). The effect of ionizing radiation on the preservation of amino acids on Mars. Earth Planet. Sci. Lett., 245,

8 Organics in Murchison Meteorite Murchison Meteorite LDMS-TOF Murchison Kerogen Pendleton & Allamandola, Ap. J. Sup. Ser. 138, 75 (2002) 8

9 Is there, or was there, life on Mars? ALH84001 Martian meteorite Antarctica 1996: nanobacteria fossils; amino acids, PAHs found 1 Becker, L., Popp, B., Rust, T., Bada, EPSL., 167, (1999); Becker, L. NRC Signs of Life Workshop, (2000). 2 Becker, L., Popp, B., Rust, T., Bada, J. Adv. Space Res., 24, 4, 477 (1999). 9

10 What is MOMA? AP MALDI = Atmospheric Pressure Matrix Assisted Laser Desorption/Ionization (ASTEP) a pulsed laser is focused onto a solid sample in ambient environment (Mars P = 5-10 Torr CO 2 ; IR or UV laser Nd:YAG 266 nm) neutral and ionized molecules are produced molecules are drawn into a mass spectrometer for analysis ITMS = Ion Trap Mass Spectrometer ions are stored in stable orbits by a 3D quadrupolar RF electric field in the presence of a rarified background gas (1-10 mtorr CO 2 works fine) ions are scanned out and detected by ramping the RF amplitude can be used to isolate individual ions for fragment analysis (MS/MS) * The AP-MALDI was merged with a GCMS proposed by a German and French team for the ExoMars mission; It is part of the MOMA suite which also includes Pyr-GC-EI-MS 10

11 MOMA Science Requirements What are our requirements? 1. the mass analyzer will need to be compatible with both laser desorption and GCMS 2. laser desorption will be carried out in situ, on solid samples presented at Mars atmospheric pressure 3. the mass range should encompass that expected for establishing the existence of organic or potentially biological relevant molecules (e.g. small peptides), ca 2,000 Da 4. the instrument will need to accommodate two ionization sources (LD and electron ionization) 11

12 Why use an ion trap? ION Trap Selection 1. most compatible with external (atmospheric) ionization using laser desorption a. TOFs (and others) require very high vacuum and a means for sample introduction b. orthogonal TOFs can be used with external ionization but require very high pumping speed to achieve high vacuum 2. has the possibility for doing MS/MS for structural analysis 3. low power ion traps have been used successfully in GCMS configurations 12

13 MOMA Instrument Concept Design What are the specific challenges? 1. combining low voltage/low power with a sufficiently high mass range 2. transferring ions formed in the Mars environment into the vacuum chamber and the ion trap 3. accommodating two sources of ions: those generated externally by LD and those generated by the GC either internally or externally using electron ionization 13

14 MOMA LDMS Instrument Concept Design Atmospheric pressure laser desorption on Earth Pulsed UV laser P=760 torr Extended capillary Atmospheric pressure laser desorption on Mars Quadrupole, hexapole or octopole ion guides P=5-10 torr Orifice 14

15 MOMA Instrument Concept Design Accommodating low power/low voltage and high mass range TABLE I. Quadrupole and Cylindrical Ion Trap Parameters Param eter Finnigan Cooks Rosetta Cylindrical Mars 1 Fundamental _ /2¹ (MHz) Maximum amplitude V max (0-p) 7.5 kv V 7.5 kv 300 V 300 V kv Radius r 0 (cm) Axis 2z 0 (cm) Mass range (Da) in mass -selective instability 650 2, mode q eject = Supplemental RF frequency (khz) 69.9 NA NA qeject NA NA NA Mass range (Da) in resonance ejection mode 3,250 NA NA NA 2,000 2,000 Mars 2 ( m / z) max = q 8V max 2 2 ( r 2z ) 2 eject Ω a Kaiser RE, Jr., Cooks RG, Moss J, Hemberger PH, Mass Range Extension in a Quadrupole Ion-trap Mass Spectrometer, Rapid Commun. Mass Spectrom. 3, (1989) b March RE, Todd JF, Quadrupole Ion Trap Mass Spectrometry, John Wiley & Sons, Inc. Hoboken NJ,

16 Uniqueness of MOMA Design What are the specific innovations? 1. combining low voltage/low power and a mass range up to 2,000 Da using lower trap frequency and a supplemental excitation with very low q eject value 2. accommodating LD and EI using internal electron ionization with the electron source on the ring electrode 3. supplemental voltage frequency scanning of the mass range 4. use of CO 2 as a bath gas in the LD mode 16

17 MOMA Prototype Design Concept Low voltage/low power and high mass range using lower trap frequency and supplemental excitation at very low q eject value MOMA Ion Trap Parameters: Fundamental _ /2¹ Maximum amplitude V max (0-p) Radius r 0 Axis 2z 0 Mass range in mass-selective instability mode q eject = khz 300 V Mars cm 0.5 cm 197 Da Supplemental RF frequency 34.4 khz Supplemental RF voltage (axial modulation) 5-10 V q eject Mass range in resonance ejection mode 2,000 Da Bath gas He or CO 2 Ionization: Ion introduction: laser desorption at Mars atmosphere (5-10 Torr) RF quadrupole ion guide 17

18 MOMA Instrument Concept A novel internal EI source with filament mounted on the ring electrode Ions from laser desorption/ionization at Mars atmosphere (5-10 Torr) Internal EI for GCMS Filament supply Electron energy Fundamental RF voltage generator 800 khz, V 0-p Supplemental RF generator 18

19 MOMA Mars Organic Molecule Analyzer Protoype built by SESI 19

20 MOMA ITMS Operational Requirements MOMA ITMS must be capable of: 1) Operating with CO 2 as a bath gas 2) Unit Mass Resolution 3) MS/MS capability Leucine Enkephalin MW MH YGGFL Y=Tyr, G=Gly F= Phe, L=Leu a 4 MS/MS MH-H m/z CO 2 pressure Peak width 1.2 x 10-4 Torr 0.5 Da 10-3 Torr 1.5 Da m/z V. Doroshenko, SESI 20

21 Leu-enkephalin (YGGFL), m/z = Bradykinin fragment1-7 (RPPGFSP) m/z = Angiotensin II (human) (DRVYI), m/z = P 14 R (polyproline) (PPPPPPPPP PPPPPR) m/z = 1534 MOMA Prototype-1 4 peptide mixture; original or raw data experimental conditions: V RF = 700 V 0 p ; P = 0.7 mtorr (CO 2 ) in the trap Leu-enkephalin (YGGFL), m/z = Bradykinin fragment1-7 (RPPGFSP) m/z = P 14 R (polyproline) (PPPPPPPPPPPPPPR ) m/z = peptide mixture; 300 points smoothing Angiotensin II (human) (DRVYI), m/z = experimental conditions: V RF = 700 V 0 p ; P = 0.7 mtorr (CO 2 ) in the trap

22 MS/MS MOMA Prototype P 14 R (polyproline) Intensity 1.0 2P (PPPPPPPPPPPPPPR) m/z = 1534 experimental conditions: trap RF 700 V 0 p 0.7 mtorr CO 2 in the trap 0.5 2P 2P P 2P P 2P P 2P P m/z 22

23 MOMA GCMS Interface Count INTERNAL IONIZATION w/ CO V, -60/+240V pulsing EXTERNAL IONIZATION w/ CO Mass 166.5V 237.5V V, /+160V pulsing JHU SOM CO 2 as the bath gas T. Evans-Nguyen 23

24 Gold Standard LD Ion Trap Mass Spectrometer Thermo LD ITMS SESI Peru Desert JHU PHA Gold Standard Jarosite 24

25 In Martian Analog Samples KT boundary extra by CH3OH in He266nm_40 #1-88 RT: AV: 88 NL: 5.92E-1 T: ITMS + p MALDI Full ms [ ] RelativeAbundance KT boundary Magic Layer 65 myr Extinction Event scan T extr by tolu in He 266nm_ #1-45 RT: AV: 45 NL: 3.03 : ITMS + p MALDI Full ms [ ] RelativeAbundance m/z Escanaba Trough Hydrothermal Vent East Pacific Rise m/z

26 PEG 600 with He and CO 2 P E G w i th H e tu rb o # R T : AV: 102 N L : 3.04 T: ITM S + p M ALD I t Full m s [ ] Peg 600 He m /z PEG C H C A w ith C 02 turbo_ # 1-45 R T : AV: 45 N L : 3.28 T: ITM S + p M ALD I t Full m s [ ] Peg 600 CO m /z 26

27 Ultramark + CHCA_ #1-45 RT: AV: 45 NL:7.38 T: ITMS + p MALDI Full ms [ ] Ultramark+CHCA with CO2 turbo_ # 1-26 RT: AV: 26 NL: 2.28 T: ITMS + p MALDI E Full ms [ ] m/z m/z Helium vs CO 2 T : p m s [ ] m/z-1416 Helium T : + p m s [ ] m /z m/z-1416 CO m /z 27

28 28