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Rapid Commun. Mass Spectrom.
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Supporting information
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Aspects of surface scanning by Direct Analysis in Real Time
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mass spectrometry employing plasma glow visualization
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Elena S. Chernetsova1,2 and Gertrud E. Morlock1*
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Institute of Nutritional Science, Chair of Food Science, Justus Liebig University Giessen, Interdis-
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ciplinary Research Center (IFZ), Heinrich-Buff-Ring 26-32, 35392 Giessen and Institute of Food
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Chemistry, University of Hohenheim, Garbenstrasse 28, 70599 Stuttgart, Germany
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On leave from Research and Innovation Department, People’s Friendship University of Russia,
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Miklukho-Maklaya st. 6, 117198 Moscow, Russia
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Running title: DART MS surface analysis with plasma glow
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Keywords: Direct Analysis in Real Time, surface scanning, neon, plasma glow visualization
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*Correspondence to: G. E. Morlock, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32,
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35392 Giessen, Germany. E-mail: Gertrud.Morlock@ernaehrung.uni-giessen.de
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Table S–1. Influence of the respective vacuum pumping rate on the S/N ratios and their repeatabili-
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ties (%RSD, n = 5) at characteristic m/z values (as listed in Table 1)
Vacuum
pumping rate
(L min–1)
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Mean
Composition of
helium for DART
ionization
S/N ratios (%RSD, n = 5)
p-Coumaric acid
Galangin
m/z (+)
m/z (–)
m/z (+)
m/z (–)
Pure He
14 (23%)
45 (12%)
325 (28%)
166 (6%)
He with 10% Ne
20 (104%)
9 (18%)
135 (86%)
72 (18%)
Pure He
29 (57%)
22 (23%)
213 (59%)
31 (18%)
He with 10% Ne
18 (34%)
4 (18%)
190 (56%)
22 (16%)
Pure He
50 (49%)
9 (14%)
257 (33%)
53 (43%)
He with 10% Ne
12 (113%)
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131 (37%)
6 (25%)
Pure He
6 (76%)
5 (60%)
15 (44%)
26 (41%)
He with 10% Ne
22 (65%)
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220 (34%)
4 (8%)
Pure He
25 (51%)
20 (27%)
203 (41%)
69 (27%)
He with 10% Ne
18 (79%)
7 (18%)
169 (53%)
26 (17%)
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Figure S–1. Surface analysis using the DART SVPA ionization source with xyz-table (3-D scanner).
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Figure S–2. Scanning DART-MS of HPTLC chromatograms of propolis samples and confirmation
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of the component identity via their ESI mass spectra for selected HPTLC zones[12]. Selected ion mon-
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itoring (SIM) mode was used for scanning HPTLC-DART-MS in the negative ionization mode
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(deprotonated molecules of chrysin at m/z 253 [M-H]- and caffeic acid at m/z 179 [M-H]-).
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Figure S–3. Selected coordinates suitable for surface scanning, providing the closest positioning of
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the standard DART ceramic cap to the analyzed surface.
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Figure S–4. Visualization of the gas impact area and heat distribution for exposure times between 4
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and 20 s and different ion source angles (0–90°) using a heat-sensitive HPTLC plate (horizontal car-
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rier; gas flow: 3 L min-1; gas heater: 300 °C; cap to plate distance: 5 mm; documentation under UV
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366 nm (top) and white light illumination (bottom). Reproduced with permission from [14] © 2015
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John Wiley & Sons, Ltd.
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Figure S–5. Comparison of DART mass spectra obtained for galangin in the positive ionization
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mode (PI) using 12 and 18 L min–1 as vacuum pumping rates (pure helium as DART gas).
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Figure S–6. Comparison of DART mass spectra obtained for p-coumaric acid in the negative ioniza-
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tion mode (NI) using 12 and 18 L min–1 as vacuum pumping rates (pure helium as DART gas).
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Figure S–7. Comparison of DART mass spectra obtained for galangin in the negative ionization
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mode (NI) using pure helium or helium with 10 % neon (vacuum pumping rate of 12 L min-1).
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Figure S–8. Simplified DART-MS scheme of gas flow directions in case of surface versus DIP-it
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analysis.
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Figure S–9. Comparison of mass signal intensities in the EIC chronograms of arbutin [M+H]+ ob-
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tained by scanning DART-MS of arbutin (6 µg applied on a rectangles of 5 x 3 mm2) on an HPTLC
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plate using the standard (a) and narrow ceramic DART cap (b).
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Video S–1 Documentation of the DART glow discharge visualization.
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