CONTRIBUTION OF ION MOBILITY FOR STRUCTURAL ANALYSIS AND ANALYTICAL CHEMISTRY: THE USE OF PROBE LIGANDS AND SELECTIVE IMS SHIFT REAGENTS

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1 CONTRIBUTION OF ION MOBILITY FOR STRUCTURAL ANALYSIS AND ANALYTICAL CHEMISTRY: THE USE OF PROBE LIGANDS AND SELECTIVE IMS SHIFT REAGENTS C. Kune, J. Far, C. Delvaux, G. Eppe, E. De Pauw 1

2 Plan: 1/ Concept of specific coordination complex formation with probe ligands 2/ Specificity depending on the presence of chemical function Proline/Valine model Contaminant of Selenomethionine intramolecular oxidation 3/ Specificity depending on the steric hindrance o DAN isomers Crown ether model o Isomers ratio determination of two isobaric selenium compounds 4/ Specificity depending on the polarity differential induce folding o DAN isomers Cyclodextrin model 2

3 Plan: 1/ Concept of specific coordination complex formation 2/ Specificity depending on the presence of chemical function Proline/Valine model Contaminant of Selenomethionine intramolecular oxidation 3/ Specificity depending on the steric hindrance o DAN isomers Crown ether model o Isomers ratio determination of two isobaric selenium compounds 4/ Specificity depending on the polarity differential induce folding o DAN isomers Cyclodextrin model 3

4 Structural elucidation Structural elucidation by ion mobility mass spectrometry (IMMS): Quad. IMS TOF MS determination: Empirical formula CCS determination: Information about 3D structure MSMS spectra Fragmentation Comparison Structure determination Structural elucidation by computational chemistry Not optimized 3D structure Structure 1 Structure 2 Structure 3 CCS 1 CCS 2 CCS 3 4

5 Structural elucidation with probe ligands Probe ligands : Molecules which interact with target ion to form specific complexes depending on their physicochemical properties Confirmation of physicochemical properties: Such as the presence of chemical moeities Such as steric hindrance Such as polarity Formation of complexes with different CCS Application as Selective Shift Reagent 5

6 Plan: 1/ Concept of specific coordination complex formation 2/ Specificity depending on the presence of chemical function Proline/Valine model Contaminant of Selenomethionine intramolecular oxidation 3/ Specificity depending on the steric hindrance o DAN isomers Crown ether model o Isomers ratio determination of two isobaric selenium compounds 4/ Specificity depending on the polarity differential induce folding o DAN isomers Cyclodextrin model 6

7 Specific coordination complex depending on the chemical functions: Proline Valine model Ligand used: Selective to priminary amino group 5.7 Selective to carboxylic acid 18-crown-6 ether Time (ms) Controlled ligand Specificity: Crown ether Selective to primary amino group K + Crown ether + K + Selective to carboxylate group Important IMS shift provided by crown ether complexation Selective shift Reagent (SSR) 7

8 Mass spectrum of SeMet (5ppm) (Synapt G2 as "QTOF MS ") Specific coordination complex depending on the chemical functions: Application as SSR Se isotope 18, Se pattern isotope of SeMet 198,47 H 3 C Se O + H 3 N O H Exact mass: uma Δm = 7.7ppm 152,4 18, , Detection of isobaric compounds confirmed by high resolution mass spectrometry with Se isotopic pattern C 5 H 12 NO 78 2 Se + 196,434,2 a.m.u SeMet Contaminant ,96 196, 196,4 C 5 H 1 NO 2 8 Se + 195, ,97 195,99 196,1 196,3 Exact mass univoque empiric formula for = 196 ion Higher Double Bound Equivalent (DBE) value Double bound or ring formation? Overlapping on the Se isotopic pattern Orthogonal separation required 8

9 Specific coordination complex depending on the chemical functions: Application as SSR for Selenomethionine Separation by IMS-MS XIC ,9789 2,84 SeMet (Aire: 2,5e 5 ) 2, ion 2, 2,25 2,5 2,75 3, 3,25 3,5 195, dt = 2,56ms 2, ion Time (ms) Use the difference in chemical group Probe ligands dt = 2,84ms 196,43 198,47 Separation by ion mobility spectrometry intramolecular oxidation hypothesis C H 3 H Se N + O O H 181 ion fragment (ammonium loss) Unable to obtain MS 2 spectra of 196 ion without interference from SeMet or in-source fragment Selenomethionine : 196 ion 18-Crown-6 Ether Selective to primary amino group Support the expected structure of 196 ion Remove the interferences from SeMet Free interferences MS 2 spectra of 196 ion 9

10 Specific coordination complex depending on the chemical functions: Application as SSR for Selenomethionine SeMet with low concentration of 18-crown-6 ether (1:1) (drift time of 196 ion) (181 ion) SeMet (Free 18-Crown-6 Ether) + (SeMet + 18-Crown-6 Ether) + 6.2, 1, 2, 3, 4, 5, 6, 7, SeMet with High concentration of 18-crown-6 ether (1:5) 2,55ms: Spectra of 196 ions and Fragments of SeMet (Free 18-Crown-6 Ether) Time (ms) (SeMet + 18-Crown-6 Ether) + Complexes with 18-crown-6 ether Time (ms), 1, 2, 3, 4, 5, 6, 7, 2,55ms: Spectra of 196 ions without interferences Interferences free MS 2 spectra of 196 ion 1

11 Specific coordination complex depending on the chemical functions: Application as SSR for Selenomethionine Se N + H H Exact mass : uma Δm = 44ppm Se N + H C H 2 Exact mass : uma Δm = 11.5ppm Se NH + O CH 2 Exact mass : uma Δm = 6.67ppm Se N H + O H 3 C O H Exact mass : uma Δm = 4.76ppm C H 3 H Se N + O O H Exact mass : uma Δm = 3.57ppm 24 H 3 C Se O C H O H Exact mass : uma (4.74e5 cps) Δm = 11.6ppm H 3 C Se Fragments of 196 ions: o o H 3 C Se + C H 2 Exact mass: uma Δm = 1.1ppm H 3 C Se + C H 2 Exact mass : uma Δm = 2.2ppm H 2 N Exact mass : uma Δm = 17.1ppm Confirme the structure of 196 ion Formation of 5-membered ring compounds Differ from those of SeMet H 3 C Se + H 3 N O O H Exact mass : uma Δm = 7.7ppm 11

12 Plan: 1/ Concept of specific coordination complex formation 2/ Specificity depending on the presence of chemical function Proline/Valine model Contaminant of Selenomethionine intramolecular oxidation 3/ Specificity depending on the steric hindrance o DAN isomers Crown ether model o Isomers ratio determination of two isobaric selenium compounds 4/ Specificity depending on the polarity differential induce folding o DAN isomers Cyclodextrin model 12

13 Specific coordination complex depending on the steric hindrance: Diaminonaphtalen isomers / Crown Ethers model SSR used: Time (ms) Dibenzo 24-crown-8 ether 1,5-DAN 1,8-DAN Time (ms) Controlled Stoechiometry: Only one primary amino group available 2 priminary amino groups available Application as Selective shift Reagent (SSR) 13

14 dt = 11.18ms MS/MS dt = 6.7ms MS/MS Specific coordination complex: Travelling wave ion mobility did not successfully separate the native isomers of 2,3- DHP-selenocystathionine The use of a nitrobenzo 15-crown-5 ether as SSR allowed to perform the separation and quantification of the isomer ratio (87-13 ). Far and coworkers, Anal. Chem (214) Vol.86, Issue 22, : Isomer A 6.7 Complexed isomer B Good agreement with theoretical values obtained by computational chemistry and isomer ratio determined from raw data by Dernovics and coworkers 14

15 Plan: 1/ Concept of specific coordination complex formation 2/ Specificity depending on the presence of chemical function Proline/Valine model Contaminant of Selenomethionine intramolecular oxidation 3/ Specificity depending on the steric hindrance o DAN isomers Crown ether model o Isomers ratio determination of two isobaric selenium compounds 4/ Specificity depending on the polarity differential induce folding o DAN isomers Cyclodextrin model 15

16 1,8-DAN 2,3-DAN 1,5-DAN Specific coordination complex depending on the polarity: DAN-Cyclodextrin model Time (ms) Time (ms) x Time (ms) Controlled folding: 1,5-DAN: Inclusion 2,3-DAN: Exclusion Application as Selective Shift Reagent (SSR) 16

17 Conclusion and perspectives Confirmation of hypothetical structure o Probe physicochemical properties As chemical functions, steric hindrance, polarity, pi stacking Use as Selective Shift Reagent o Allow a control of the arrival time distribution of ion Separation of isomers Obtention of interference free MS 2 spectra Perspectives: o Use ligands to probe the three dimensional structural of larger (bio)molecules As peptide, protein, DNA 17

18 Aknowledgement: Laboratory of Mass Spectrometry o Docteur Johann Far Professeur Gauthier Eppe o Cédric Delvaux Professeur Edwin De Pauw Laboratory of Theoritical Physical Chemistry o Professeur Françoise Remacle 18

19 Thanks for your attention 19

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