Mutual storage mode ion/ion reactions in a hybrid linear ion trap

Liang

McLuckey

2005

Self Cite

116

A pulsed dual electrospray ionization source has been developed to generate positive and negative ions for subsequent ion/ion reaction experiments. The two sprayers, typically a nano-electrospray emitter for analytes and an electrospray emitter for reagents, are positioned in a parallel fashion close to the sampling orifice of a triple quadrupole/linear ion trap tandem mass spectrometer (Sciex Q TRAP). The potentials applied to each sprayer are alternately pulsed so that ions of opposite polarity are generated separately in time. Ion/ion reactions take place after ions of each polarity are sequentially injected into a high-pressure linear ion trap, where axial trapping is effected by applying an auxiliary radio frequency voltage to the end lenses. The pulsed dual electrospray source allows optimization of each sprayer and can be readily coupled to any spray interface with no need for instrument modifications, provided the potentials required to transmit the ion polarity of interest can be alternated in synchrony with the emitter potentials. Ion/ion reaction examples such as charge reduction of multiply charged protein ions, charge inversion of peptides ions, and protein-protein complex formation are given to illustrate capabilities of the pulsed dual electrospray source in the study of gas-phase ion/ion chemistry. T he advent of electrospray ionization (ESI) mass spectrometry has revolutionized the analysis of many biologically important macromolecules [1,2]. Both the polarity and the magnitude of the charge associated with an ionized biomolecule play important roles in the use of tandem mass spectrometry for the identification and structural characterization of the biomolecule from which the ions were derived. Ion/ion reactions provide efficient means for manipulating the identities of gas-phase ions after their initial formation [3,4], including altering ion polarity and absolute charge. Applications of charge manipulation via ion/ ion reactions include: mixture analysis [5][6][7][8], especially with the application of the "ion parking" technique for gas-phase concentration and charge state purification [9], the formation of ions that cannot be directly produced by ESI for subsequent tandem mass spectrometry studies [10], and the reduction of the product ion charge states to singly and doubly charged so as to simplify the interpretation of product ion spectra [11][12][13][14][15][16]. Electron-transfer ion/ion reactions have recently been described as a means of inducing structurally informative dissociation, giving rise to cleavages analogous to those noted in electron capture dissociation [17][18][19][20][21]. In this regard, ion/ion reactions play a role as a probe of primary structure.Electrodynamic ion traps, either a quadrupole ion trap or a linear ion trap (LIT), are particularly useful reaction vessels for ion/ion reactions because of their ability to store oppositely-charged ions simultaneously [22] as well as their ion isolation and MS n functionalities [23]. Most ion/ion reaction studies involving m...

Section: Charge Reduction Of Multiply Charged Positive Ionsmentioning

confidence: 99%

Pulsed dual electrospray ionization for In/In reactions

Liang

McLuckey

2005

Self Cite

116

“…An alternative means for creating an RF barrier for mutual ion polarity storage along the z-dimension is to unbalance the RF applied to the quadrupole array [40,41]. When the DC offset of the quadrupole array and the containment lenses are at the same level, subtracting a fraction of RF amplitude applied to one set of opposing rods and increasing by the same amount the RF level on the pair of rods is equivalent to applying the same fraction of RF to the containment lenses.…”

Section: Mutual Storage Mode Ion/ion Reactions In Lin-ear Ion Trapsmentioning

confidence: 99%

“…Ion/ion reactions in a linear ion trap operated in an unbalanced RF condition (54%) were demonstrated on a modified hybrid triple quadrupole/linear ion trap mass spectrometer, where an atmospheric sampling glow discharge source was mounted to the side of the third quadrupole (Q3) of the assembly for directing negative reagent ions into Q3 between the rods [41]. The schematic diagram of the apparatus is provided in Figure 6.…”

Section: Mutual Storage Mode Ion/ion Reactions In Lin-ear Ion Trapsmentioning

confidence: 99%

Evolution of instrumentation for the study of gas-phase ion/ion chemistry via mass spectrometry

McLuckey

2008

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The scope of gas-phase ion/ion chemistry accessible to mass spectrometry is largely defined by the available tools. Due to the development of novel instrumentation, a wide range of reaction phenomenologies has been noted, many of which have been studied extensively and exploited for analytical applications. This perspective presents the development of mass spectrometry-based instrumentation for the study of the gas-phase ion/ion chemistry in which at least one of the reactants is multiply charged. The instrument evolution is presented within the context of three essential elements required for any ion/ion reaction study: the ionization source(s), the reaction vessel or environment, and the mass analyzer. Ionization source arrangements have included source combinations that allow for reactions between multiply charged ions of one polarity and singly charged ions of opposite polarity, arrangements that enable the study of reactions of multiply charged ions of opposite polarity and, most recently, arrangements that allow for ion formation from more than two ion sources. Gas-phase ion/ion reaction studies have been performed at near atmospheric pressure in flow reactor designs and within electrodynamic ion traps operated in the mTorr range. With ion trap as a reaction vessel, ionization and reaction processes can be independently optimized and ion/ion reactions can be implemented within the context of MS n experiments. Spatial separation of the reaction vessel from the mass analyzer allows for the use of any form of mass analysis in conjunction with ion/ion reactions. Time-of-flight mass analysis, for example, has provided significant improvements in mass analysis figures of merit relative to mass filters and ion traps. The development and evaluation of new tools has clearly been a central activity and contributor to the dramatic advances in the capabilities of mass spectrometry over the past several decades. In this perspective, we relate the evolution of instrumentation for research activities focused on the study and use of ion/ion reactions and offer it as one example of many where progress in an area of science is intimately related to and dependent on the development of instrumentation. It is provided in appreciation for the inspirational example of creativity in instrumentation development [1] provided by Cooks over the years. Electrospray ionization (ESI) [2], among its many contributions, enabled the development of macro-molecule ion/ ion chemistry as a research area. The multiple-charging phenomenon associated with electrospray makes possible the generation of multiply charged reactant ions. This capability leads to the possibility that at least one ion/ion reaction product can retain charge, which makes such a product directly amenable to study with mass spectrometry. In the past two decades, significant progress has been made in understanding and exploring the gas-phase ion/ion chemistry of high mass multiply charged ions. A variety of potential analytical applications have been developed accordingly. Co...

“…The Q TRAP electronics were modified to allow superposition of an auxiliary RF signal to the containment lenses of Q2 and Q3 of the LIT [36]. The frequency and amplitude of auxiliary RF signal applied to the containment plates was optimized for each ion/ion reaction experiment.…”

Section: Apparatus Setupmentioning

confidence: 99%

A pulsed triple ionization source for sequential ion/ion reactions in an electrodynamic ion trap

Liang

Han

et al. 2007

Self Cite

A pulsed triple ionization source, using a common atmosphere/vacuum interface and ion path, has been developed to generate different types of ions for sequential ion/ion reaction experiments in a linear ion trap-based tandem mass spectrometer. The triple ionization source typically consists of a nano-electrospray emitter for analyte formation and two other emitters, an electrospray emitter and an atmospheric pressure chemical ionization emitter or a second nano-electrospray emitter for formation of the two different reagent ions. The three emitters are positioned in a parallel fashion close to the sampling orifice of the tandem mass spectrometer. The potentials applied to each emitter are sequentially pulsed so that desired ions are generated separately in time and space. Sequential ion/ion reactions take place after analyte ions of interest and different set of reagent ions are sequentially injected into a linear ion trap, where axial trapping is effected by applying an auxiliary radio frequency voltage to the end lenses. The pulsed triple ionization source allows independent optimization of each emitter and can be readily coupled to any atmospheric pressure ionization interface with no need for instrument modifications, provided the potentials required to transmit the ion polarity of interest can be synchronized with the emitter potentials. Several sequential ion/ion reactions examples are demonstrated to illustrate the analytical usefulness of the triple ionization source in the study of gas-phase ion/ion chemistry. . Electron-transfer reactions appear to be a highly useful means for deriving the primary structure information of peptides and proteins [7][8][9][10][11].Most ion/ion reaction studies involving biomolecules are conducted in one of two ways. The first approach is to mix the oppositely charged reactant ions at or near atmospheric pressure before sampling ions into a mass spectrometer. The second approach is to admit the ions of opposite polarity into an electrodynamic ion trap for subsequent mutual storage and reaction. The former approach has employed a spray ionization method as one of the ion sources and either a discharge [12][13][14], radioactive source [15,16], or another spray ionizer [17] as the second ion source. In this approach, the ion sources have been operated simultaneously and, in general, continuously. This approach avoids the need for instrument modification to accommodate an additional ion source interface but it is not conducive to MS n studies. In the latter approach, electrodynamic ion traps, either a quadrupole ion trap or a linear ion trap (LIT), are used as reaction vessels for ion/ion reactions due to their ability to store oppositelycharged ions simultaneously [18] as well as their ion isolation and MS n functionalities [19].Sequential ion/ion reactions have been found to be useful in a number of applications in the analysis of peptides and proteins. One example is the increase of the absolute charge state of a polypeptide ion, which has been achieved via two sequential i...