Solvation in Gas-Phase Reactions of Sulfonic Groups Containing Ionic Liquids in Electrospray Ionization Quadrupole Ion Trap Mass Spectrometry

Abstract

In electrospray ionization (ESI) quadrupole ion trap mass spectrometry, certain fragment ions generated in the ion trap from a series of sulfonic groups containing ionic liquids (ILs) are found to undergo ion-molecule reactions with ESI solvent molecules (water, acetonitrile and methanol) to form adduct species. These unexpected solvated fragment ions severely complicate the interpretation of mass spectrometric data. Multi-stage fragmentation mass spectra were used to ascertain the chemical structures of these adduct species. It is important that solvation must be taken into account in order to prevent erroneous data interpretation for sulfonic groups containing ILs.

Characterization of Wax Esters by Electrospray Ionization Tandem Mass Spectrometry: Double Bond Effect and Unusual Product Ions

“…These water-product ion adducts resulted from ion-water interactions in the collision cell [35–42], where the water molecules were proposed to originate from solvent molecules [36, 42] or being delivered by the collision gas [37, 40]. Similarly, in our study, the water molecule appeared to originate from a combination of solvent and collision gas.…”

“…Interestingly, a number of studies have reported unusual adducts between water and direct product ions derived from a variety of species including guanine [35], guanosine [36, 37], acetophenone [38, 39], halogenated benzoic acids [40], various substituted isoquinoline-3-carboxamides [41] and a series of sulfonic groups-containing ionic liquids [42] in either positive mode [36–39, 41, 42] or negative mode [35, 40]. These water-product ion adducts resulted from ion-water interactions in the collision cell [35–42], where the water molecules were proposed to originate from solvent molecules [36, 42] or being delivered by the collision gas [37, 40].…”

“…Interestingly, dissociation of [RCOOH 2 + CH 3 OH] + resulted in [RCOOH 2 ] + and the unusual product ions [RCOOH 2 + H 2 O] + and [RCO + CH 3 OH] + , which corresponded to exchange of CH 3 OH with H 2 O, and loss of water, respectively (Figure 2). Adducts between methanol and direct product ions have also been reported in several studies including ESI-MS/MS analysis of guanosine [36] and a series of sulfonic groups-containing ionic liquids [42] as well as APCI-MS/MS analysis of purine and pyrimidine [43]; in addition, two of the studies also reported that MS 3 of the methanol-direct product ion adducts resulted in the loss of methanol or exchange of methanol with water. [42, 43]…”

Electrospray mass spectrometric studies of nickel(II)-thiosemicarbazones complexes: Intra-complex proton transfer in the gas phase ligand exchange reactions

“…Therefore, the two product ions at m/z 299 and m/z 308 were ascribed to [Ni 2+ exchange reactions of metal complexes have been reported in the EI triple quadrupole [36], the quadrupole ion trap [37] and the ESI FT-ICR mass spectrometer [38]. The coordinative unsaturated metal complexes [26][27][28], some organic ions [39,40], and even halide anions [41] have been documented to undergo the gas-phase ion-molecule reactions with ESI solvent molecules to form adduct species in ion trap. Interestingly, the abundant product ion at m/z 295, corresponding to [Ni 2+ (M−H) − (N 2 )] + , can be interpreted as the ligand exchange reaction of CI-a with the residual drying gas (N 2 ) in the ion trap.…”

Rapid differentiation ofortho-,meta-, andpara-isomers of halogenated phenylmethylidene hydrazinecarbodithioates by metal complexation and electrospray ionization mass spectrometry

“…Dissociation of the monoisotopic precursor ion [2M X -H + Ni] + in the MS 2 experiment mainly generates the product ion [M X + SCH 3 + Ni] + by losing a neutral species of the corresponding N-isothiocyanato(halogenated phenyl) methanimine ( Supplementary Fig. S1(b), Scheme S1 and [56,[64][65][66][67][68][69][70][71] It is worthy of note that the residual CH 3 CN molecules in the ion trap come from the ESI solvent through the heated steel capillary, H 2 O from the ESI solvent or the ambient atmosphere, and N 2 from the drying gas or the ambient atmosphere. Our previous studies have also shown that CID of [M + SCH 3 + Ni] + leads to these solvated species.…”