Ionic Liquid Matrix-Enhanced Secondary Ion Mass Spectrometry: the Role of Proton Transfer

Ionic Liquid Matrix-Enhanced Secondary Ion Mass Spectrometry: The Role of Proton Transfer: Supporting Information

Jennifer J. Dertinger, Amy V. Walker[*]

Department of Materials Science and Engineering, RL 10, University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX 75080

Figure 1.Structures of a) DPPC; b) d62 DPPC; and c) d75 DPPC.

Figure 2.Structures of the ionic liquid matrices employed: a) MI CHCA; b) dMI CHCA; c) MI2 CHCA; d) EI CHCA; e) BI CHCA; and f) trip CHCA.

Figure 3. SIMS spectra from m/z 187 to m/z 191 showing the (CHCA – H)- ion region for DPPC, d62 DPPC and d75 DPPC in a MI2CHCA matrix. The spectra are normalized to the intensity of (CHCA – H)- to make clear any changes in the (CHCA – H + 1)- and (CHCA – 2H + 2)- ion intensities.

Figure 4.TOF SIMS spectra centered at m/z 185 of DPPC and d62 DPPC in a MI CHCA matrix.

Figure 5.a)Variation of secondary ion enhancements for the protonated molecular ion of DPPC and d62 DPPC with matrix cation. b) Variation of the ratio of I((cation + D)+ to I(cation + H)+ with matrix cation using the analyte d62 DPPC.

Note: The molecular ion enhancements reported are lower for DPPC and d62 DPPC in these experiments because the experiments were performed using a slightly different spin coating conditions. In this case the concentration of DPPC and d62 DPPC were mixed with the ionic liquid for slightly longer than 5 mins before spin coating (due to problems with the spin coater).

Reference Spectra for the Ionic Liquids Employed in this Study

All ionic liquids were characterized using 1H NMR spectroscopy, IR spectroscopy and TOF SIMS. The spectra are shown below in the following order. For each ionic liquid the positive mass spectrum will be first, followed by the negative mass spectrum, and the IR spectrum. On the second page will be the 1H NMR spectra showing the proton shift. The ionic liquids are ordered alphabetically by acronym.

BI CHCA

Figure 6.Positive and negative ion mass spectra and IR spectrum of BI CHCA.

Figure 7.1H NMR spectrum of BI CHCA.

dMI CHCA

Figure 8.Positive and negative ion mass spectra and IR spectrum of dMI CHCA.

Figure 9.1H NMR spectrum of dMI CHCA.

EI CHCA

Figure 10.Positive and negative ion mass spectra and IR spectrum of dMI CHCA.

Figure 11.1H NMR spectrum of dMI CHCA.

MI CHCA

Figure 12.Positive and negative ion mass spectra and IR spectrum of MI CHCA.

Figure 13.1H NMR spectrum of MI CHCA.

MI2CHCA

Figure 14.Positive and negative ion mass spectra and IR spectrum of MI2CHCA.

Figure 15.1H NMR spectrum of MI2CHCA.

Trip CHCA

Figure 16.Positive and negative ion mass spectra and IR spectrum of trip CHCA.

Figure 17.1H NMR spectrum of trip CHCA.

[*] Address reprint requests to Amy V. Walker, Department of Materials Science and Engineering, RL10, University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX 75080; Ph: 972 883 5780; Fax: 972 883 5725; email: