1. Ionic liquids in analytical chemistry and their applications in mass spectrometry 13 September 2006 Farzad Fani Pakdel

2. What are ionic liquids? Ionic liquids (ILs) are pure organic salts that ° have a melting point below 100°C. Some are liquid at room temperature (RTIL) The cation usually contains nitrogen with 4 covalent bonds G. A. Baker et al. Analyst, 2005, 130, 800–808 http://www.rsc.org/chemistryworld/Issues/2004/April/saccharine.asp -AgX

3.  Low vapor pressure  High viscosity  Good solvents for both organic and inorganic compounds  Broad liquid range  High conductivity  Wide electrochemical window (4.5 - 6 v)  Thermal and oxidative stability  Nonflammability Properties of ionic liquids http://www.le.ac.uk/ch/staff/apa1_resint.html

4. History ° 1914: knowledge of liquid alkylammonium nitrates [EtNH3+][NO3-] mp = 12°C 1970s: Haloaluminate RTILs were used as electrolyte instead of molten salts in thermal batteries 1992: Synthesis of new ILs with PF6 – and BF4 – anions and following that: Air and moisture stable ionic liquids widely used in synthetic chemistry as solvents Analytical chemists have started taking advantage of their properties Ionic liquid related Publications vs. year G. A. Baker et al. Analyst, 2005, 130, 800–808

5. Out line Ionic liquids in analytical chemistry:  Mass spectrometry: MALDI (Matrix assisted laser desorption ionization) Matrix properties in MALDI-MS Ionic liquids as matrices Quantitative and reproducible Electrospray  Chromatography  Extraction  Electrochemistry  Electrophoresis  Spectroscopy

6. How does MALDI work? http://www.chm.bris.ac.uk/ms/theory/maldi-ionisation.html

7. Effective MALDI matrix Cocrystallize with sample (solid matrix) Dissolve the sample (liquid matrix) Strong absorption of laser light (  > 10 000) Vacuum stable Promote the ionization of the sample Form a homogenous solution with analyte (shot to shot reproducibility)

8. Solid matrices Cocrystallize with analyte Strong absorption of laser light Vacuum stable Promote the ionization of the sample Form a homogenous solution with analyte (reproducibility)  -cyano-4-hydroxycinnamic acid (CHCA) sinapinic acid (SA) Hot spot

9. Liquid matrices Do not contain the desired UV chromophore: have to add other components Not Vacuum stable: changeable matrix due to volatility evaporation metal nano-particles added to glycerol Glycerol: vacuum stable

10. Ideal matrix A UV absorbing liquid that has a low vapor pressure Dissolves the sample and can promote sample ionization (proton transfer) IONIC LIQUIDS

11. Ionic Liquids as Matrixes for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Daniel W. Armstrong, Li-Kang Zhang, Lingfeng He and Michael L. Gross * Iowa State University Ames, Iowa Analytical Chemistry. 2001, 73(15), 3679 * Washington University St. Louis, Missouri

12. Paper summary 36 different ionic liquids and 2 solid matrices were tested as MALDI matrix: 4 different analytes were used to study: Intensity and reproducibility for different matrices were investigated Bradykinin (1060) arg - pro - pro - gly - phe - ser - pro - phe – arg PEG (2000) Human Insulin (5809) and Horse skeletal Apomyoglobin (16953) http://www.sickkids.ca/HowellLab/custom/insulin.asp (CHCA)sinapinic acid (SA)

13. Experimental Acetonitrile/ water (2/1, 0.1% TFA) SS plate matrix Water ( ACN-water for PEG) Analyte 4L4L 1L1L 4L4L air stream Voyager-RP Biospectrometry time-of-flight mass spectrometer positive-ion mode was used Nitrogen laser (337-nm, 3-ns pulse), with a intensity up to 200  J /pulse

14. 18 ILs with no signal No proton

15. Sinapinic acid and its organic salts as matrix Matrix is a solid organic acid IL with signal equal to or higher than organic acid No Signal

16. Out line CHCA and its organic salts 40 000 24 000 50 00040 000 57 000 53 000 52 000 56 000 45 000 50 000 55 000 56 000 45 000 50 000 52 000 64 000 62 000 34 000 61 000

17. Sample mass spectra Human Insulin (5809) Horse Apomyoglobin (16953) Solid matrix IL matrix 1800016000170001800016000170001600017000 700050006000700050006000700050006000 Intensity ( x 10 4 ) m/z

18. PEG mass spectra Solid matrix IL matrix

19. Reproducibility CHCA Ionic liquid

20. Ionic-Liquid Matrices for Quantitative Analysis by MALDI-TOF Mass Spectrometry Ying L. Li and Michael L. Gross Washington University St. Louis, Missouri J Am Soc Mass Spectrom. 2004, 15, 1833–1837

21. Calibration curves for the MALDI quantification of Bradykinin Internal standard: substance P

22. MALDI quantification of bradykinin, melittin and bovine insulin Substance P internal standard

23. Advantages and disadvantages of ILs in MALDI Homogenous solutions with different analytes: Better shot to shot reproducibility No need for search of hot spot Many choices of ionic liquids for different analytes No signal depletion (even after 100 laser shots) Quantitative analysis also possible (as well as solid matrix) Not commercially available yet The relation between signal and IL structure is not well understood Quantitative analysis for mixtures was not shown

24. Out line Ionic liquids in analytical chemistry:  Mass spectrometry: MALDI (Matrix assisted laser desorption ionization) Matrix properties in MALDI-MS Ionic liquids as matrices Quantitative and reproducible Electrospray  Chromatography  Extraction  Electrochemistry  Electrophoresis  Spectroscopy

25. Electrospray ionization in hexane 1 st ESI in non-polar solvent Analyte: [HNEt 3 ][HFe 3 (CO) 11 ] M. Henderson, J. McIndoe. Chem. Commun., 2006, 2872–2874 P C6C6 C6C6 C6C6 C 14 [N(SO 2 CF 3 ) 2 ] 2 + _ A = C = Addition of IL (CA) dissolves the analyte In hexane

26. Gas chromatography GC capillary was coated by polymerization of ILS as stationary phase. Column temperature: 100 °C hold 2 min, 15 °C/min to 260 °C. monomer Cross-linker Armstrong, D.W; Anderson, J. Analytical Chemistry, 2005, 77 (19) Separation of fatty acid methyl esters (C6-C24)

27. Extraction G. A. Baker et al. Analyst, 2005, 130, 800–808

28. Electrochemistry G. A. Baker et al. Analyst, 2005, 130, 800–808 Cyclic voltammogram of the O2 / O2 - 5  m radius gold microdisk electrode, = 500 mV/ s Electrochemical detection of gases in IL [N6222][Tf2N] M. C. Buzzeo, R. G. Evans and R. G. Compton, ChemPhysChem, 2004, 5, 1106–1120.

29. Electrophoresis Detection of different polyphenols in grape seed extract G. A. Baker et al. Analyst, 2005, 130, 800–808 A-C: grape seed extract D: polyphenol standards IL 1-ethyl-3-methylimidazolium Tetrafluoroborate used as running electrolyte

30. Spectroscopy Jared L. Anderson, Daniel W. Armstrong and Guor-Tzo Wei, Analytical Chemistry. 2006, 78(9), 2893-2902 Fluorescence spectra of Rhodamine 6G dye in 4 different IL solvents and deionized water (DI) Fluorescence enhancements in IL

31. Conclusion  The application of Ionic liquids in analytical chemistry is growing: Chromatography MALDI Electrochemistry Extraction  New ionic liquids will emerge  Commercial availability of ILs will increase  Possible new applications: Nano science (charged nano-particles, hydrophobic nano-pores) Laser Induced Back Ablation New particles: (drug delivery, liquid aerosol)

32. Acknowledgments: Dr. Nicolo Omenetto Winefordner-Omenetto- Smith group Dr. David Powell Dr. Kathryn Williams

33. THANK YOU!