Tandem mass spectrometry of poly(ethylene glycol) lithium-attachment ions

Ammonium adducts of trimethylsilyl-terminated poly(dimethylsiloxane) (CH 3 -PDMS) produced by electrospray ionization were submitted to collision induced dissociation and revealed a particular MS/MS behavior: the same three main product ions at m/z 221, 295, and 369 were always generated in very similar relative abundances regardless of the size of the precursor ion. Combining accurate mass measurements and ab initio calculation allowed very stable cyclic geometries to be obtained for these ionic species. Dissociation mechanisms were proposed to account for the three targeted ions to be readily generated in a two-step or a three-step reaction from any CH 3 -PDMS ammonium adducts. A second set of three product ions was also observed with low abundance at m/z 207, 281, and 355, which were shown in MS 3 experiments to be formed in secondary reactions. An alternative dissociation process was shown to consist of a concerted elimination of ammonia and methane and the need for a methyl of an end-group to be involved in the released methane molecule would account for this reaction to mainly proceed from the smallest precursor ions.

Section: Introductionmentioning

confidence: 99%

Tandem Mass Spectrometry of Trimethylsilyl-Terminated Poly(Dimethylsiloxane) Ammonium Adducts Generated by Electrospray Ionization

Fouquet

Humbel

Charles

2011

“…Dissociation pathways have been studied for a large variety of polymers, such as PEO [11][12][13][14][15][16][17][18][19][20][21][22][23][24], PS [20,[23][24][25][26][27][28][29][30], or poly(methylmethacrylate) (PMMA) [20, 21, 23, 30 -32]. In contrast, few MS studies have been reported for PMAA and most of them focused on the analysis of volatile thermal degradation products of the polymer [33,34].…”

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confidence: 99%

Tandem mass spectrometry of poly(methacrylic acid) oligomers produced by negative mode electrospray ionization

Giordanengo

Viel

Allard-Breton

et al. 2009

Dissociation of small poly(methyl acrylic acid) (PMAA) anions produced by electrospray was characterized by tandem mass spectrometry. Upon collisional activation, singly, and doubly deprotonated PMAA oligomers were shown to fragment via two major reactions, dehydration and decarboxylation. The elimination of a water molecule would occur between two consecutive acid groups in a charged-remote mechanism, giving rise to cyclic anhydrides, and was shown to proceed as many times as pairs of neutral pendant groups were available. As a result, the number of dehydration steps, together with the abundance of the fragment ions produced after the release of all water molecules, revealed the polymerization degree of the molecule in the particular case of doubly charged oligomers. For singly deprotonated molecules, the exact number of MAA units could be reached from the number of carbon dioxide molecules successively eliminated from the fully dehydrated precursor ions. In contrast to dehydration, decarboxylation reactions would proceed via a charge-induced mechanism. The proposed dissociation mechanisms are consistent with results commonly reported in thermal degradation studies of poly(acrylic acid) resins and were supported by accurate mass measurements. These fragmentation rules were successfully applied to characterize a polymeric impurity detected in the tested PMAA sample. (J Am Soc Mass

“…Our previous study was focused on alcohol ethoxylates whose end-groups are linked to polyglycol chains via ether-type C™O bonds (i.e., polyglycol ethers). The results generated therein were compared to earlier studies of the same type of polyglycols employing fast atom bombardment (FAB) MS/MS by Latimer and coworkers [22][23][24][25].Poly(ethylene glycol) ester, especially fatty acid methyl ester ethoxylate (FAMEE), is another class of polyglycol which can be used as an alternative to alcohol ethoxylates in many industrial applications. With varying alkyl chain lengths in the fatty acid moiety, a wide range of hydrophilic lipophilic balance (HLB) values can be achieved to suit different applications [14].…”

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confidence: 99%

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confidence: 99%

Characterization of poly(ethylene glycol) esters using low energy collision-induced dissociation in electrospray ionization mass spectrometry

Chen

2002

A method of characterizing polyglycol esters, an important class of industrial polymer, has been developed using electrospray ionization ion trap mass spectrometry (ESI ITMS). The fragmentation behavior of polyglycol esters is found to be different from that of polyglycols whose functional end groups are linked to the polymer chain via ether bonds (i.e., polyglycol ethers). The fragmentation pattern of an oligomer ion generated by low-energy collisioninduced dissociation is strongly dependent on the type of cation used for ionization. It is shown that structural information on the polymer chain and end groups is best obtained by examining the fragment ion spectra of oligomers ionized by ammonium, alkali, and transition metal ions. T andem mass spectrometry using either matrixassisted laser desorption ionization (MALDI) or electrospray ionization (ESI) is being developed as a tool for polymer structural characterization [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. We are particularly interested in characterizing functional polyglycols, including poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG), and their copolymers [12][13][14][15][16][17][18][19]. Structural characterization of this type of polymer is important because polyglycols are widely used in industry with their properties strongly depending on not only molecular weights, but also structures and compositions. Recently, polyglycols have also been increasingly used in biotechnical and biomedical applications such as the development of slow releasing drugs [20,21]. Traditionally, polyglycols were thought to be difficult to fragment in low-energy CID tandem MS. In our recent work, we demonstrated that lithium and transition metal ions could form adduct ions with polyglycol in ESI, and these adduct ions could readily undergo fragmentation [15,16]. The resulting fragment ion spectra were very informative for the structural characterization of polyglycol. Our previous study was focused on alcohol ethoxylates whose end-groups are linked to polyglycol chains via ether-type C™O bonds (i.e., polyglycol ethers). The results generated therein were compared to earlier studies of the same type of polyglycols employing fast atom bombardment (FAB) MS/MS by Latimer and coworkers [22][23][24][25].Poly(ethylene glycol) ester, especially fatty acid methyl ester ethoxylate (FAMEE), is another class of polyglycol which can be used as an alternative to alcohol ethoxylates in many industrial applications. With varying alkyl chain lengths in the fatty acid moiety, a wide range of hydrophilic lipophilic balance (HLB) values can be achieved to suit different applications [14]. They are extensively used as non-ionic bases for cosmetics and pharmaceuticals, non-ionic emulsifiers for vegetable and mineral oils, thickening agents for creams, anti-static agents for plastics, and non-ionic surfactants. Despite active MS study on alcohol ethoxylates [12][13][14][15][16][17][18][19], the literature on ester ethoxylates is scarce [5,16,63].In this work, we report a metho...