Supplementary information
Mechanistic study of the collision-induced
dissociation of sodium-cationized polylactide
oligomers : A joint experimental and theoretical
investigation
Julien De Winter,a Vincent Lemaur,b Philippe Marsalb,d, Olivier Coulembier,c Jérôme Cornil,b
Philippe Dubois,c Pascal Gerbaux a
a
Mass Spectrometry Research Group, Centre Interdisciplinaire de Spectrométrie de Masse
(CISMa), University of Mons, 20 Place du Parc, B-7000 Mons
b
Laboratory for Chemistry of Novel Materials, University of Mons, 20 Place du Parc, B-7000
Mons
c
Center of Innovation and Research in Materials and Polymers (CIRMAP), Laboratory of
Polymeric and Composite Materials, University of Mons, 20 Place du Parc, B-7000 Mons
d
CINaM-CNRS, Université Aix-Marseille 2 & 3, Campus de Luminy, Case 913 13288 Marseille
Cedex 9, France
Corresponding author:
Dr Pascal Gerbaux
Mass Spectrometry research Group, Centre Interdisciplinaire de spectrométrie de masse
University of Mons
20, Place du Parc
7000 Mons
Belgium
1
Pascal.Gerbaux@umons.ac.be
Tel +32 65 37 33 42
Scheme S.I. 1 : Collision-induced dissociation of Na+-cationized H3C-PLA-OH oligomers :
Competition between end-group specific decompositions (routes A and B) and ion series C.
Scheme S.I. 2 : Collision-induced dissociation of Na+-cationized H3CO-PLA-O-(C=O)CH3
oligomers.
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Scheme S.I. 3 : isomeric structures corresponding to cyclic PLA and to linear PLA presenting
a carboxylic acid and an acrylic acid ester functions as the end-groups.
Scheme S.I. 4 : Mechanistic proposal for the loss of 72 u from collisionally-excited sodiumcationized PLA oligomers.
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a
b
Figure S.I. 1 : Expanded view between m/z 800 and m/z 850 for single stage mass spectrum of
H-PLA-OH, a) and b) are respectively recorded before and after H/D Exchange. A cyclic species
is not able to exchange any hydrogen atom by deuterium atom when dissolved in a deuterated
solvant, linear-PLA oligomers presenting a carboxylic acid function as the end-group are
expected to exhibit a progressive replacement of the carboxylic hydrogen atom by a deuterium
atom. S.I.1a presents an expanded view of Figure 1 (from m/z 800 to m/z 850). The signal at m/z
833 was already studied in this work and corresponds to H-PLA-OHNa+ cations containing 11
lactic acid units. The H/D exchange experiment is expected to confirm that the m/z 815 cations
are sodium-cationized cyclic-PLA presenting 11 monomeric units. As exemplified from S.I.1b,
upon dissolution in a 1:1 mixture of acetonitrile and D2O, the m/z 833 signal is clearly shifted
two units mass higher upon exchange of both hydrogen atoms from both end-groups. On the
other hand, the m/z 815 signal remains unchanged confirming the cyclic nature of the
corresponding ions.
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Figure S.I. 2: CID spectrum of Na+ cationized cyclic-PLA (m/z 815; Argon collision gas; 45 eV
collision energy).
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