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Linear ion traps are finding new applications in many areas of mass spectrometry. In a linear ion trap, ions are confined radially by a two-dimensional (2D) radio frequency (RF) field, and axially by stopping potentials applied to end electrodes. This review focuses on linear ion trap instrumentation. Potentials and ion motion in linear multipole fields and(More)
A detailed description of a linear ion trap time-of-flight (TOF) mass spectrometer system, capable of sequential mass spectrometry (MS(n)), is given. Many improvements have been incorporated since the initial description of this system (Rapid Commun. Mass Spectrom. 1998; 12: 1463-1474). The pressure in the trap has been lowered from 7.0 to 1.8 mTorr,(More)
Near pH 2.0, lysozyme in water is in its native conformation, and in water/methanol (2/8) it adopts a helical denatured conformation (Kamatari et al. Protein Sci. 1998, 7, 681-688). Hydrogen/deuterium (H/D) exchange of lysozyme in solution confirms that it is partially unfolded at pH 2.0 in water/methanol (v/v = 2/8). With electrospray ionization (ESI) mass(More)
A high-throughput liquid chromatography/tandem mass spectrometry (LC/MS/MS) method, which combines on-line sample extraction through turbulent flow chromatography with a monolithic column separation, has been developed for direct injection analysis of drugs and metabolites in human plasma samples. By coupling a monolithic column into the system as the(More)
The hydrogen/deuterium (H/D) exchange of gas-phase ions of holo- and apo-myoglobin has been studied by confining the ions in a linear quadrupole ion trap with D(2)O or CD(3)OD at a pressure of several mTorr. Apo-myoglobin ions were formed by collision-induced dissociation of holo-myoglobin ions between the orifice and skimmer of the ion sampling system. The(More)
The gas phase H/D exchange reaction of bradykinin ions, as well as fragment ions of bradykinin generated through collisions in an orifice skimmer region, have been studied with a linear quadrupole ion trap (LIT) reflectron time-of-flight (rTOF) mass spectrometer system. The reaction in the trap takes only tens of seconds at a pressure of few mTorr of D2O or(More)
Methods to reduce mass shifts caused by space charge with mass-selective axial ejection from a linear quadrupole ion trap are investigated. For axial ejection, dipole excitation is applied to excite ions at q ≈ 0.85. The trapping radiofrequency (rf) voltage is scanned to bring ions of different m/z values into resonance for excitation. In the fringing field(More)
BACKGROUND The skeletal symmetric structure of chlorhexidine predicts that each doubly charged molecular ion may generate two para-chlorbenzenguanidines daughter ions through bond cleavage at two protonation sites, thus generating better sensitivity in MRM transition than that involving singly charged molecular ions. This unique nature can be used to(More)
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