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. Author manuscript; available in PMC: 2014 Nov 21.
Published in final edited form as: Int J Mass Spectrom. 2013 Nov 1;353:84–92. doi: 10.1016/j.ijms.2013.04.009

Fig. 1.

Fig. 1

(+)-DESI-MS spectra of (a) 5 µM intact insulin solution in water containing 1% formic acid; (b) 5 µM insulin solution after online pepsin digestion and before electrolytic reduction (applied potential: 0 V); and (c) 5 µM insulin solution after online pepsin digestion and online electrolytic reduction (applied potential: −1.5 V).