Tandem mass spectrometry in an electrostatic linear ion trap modified for surface-induced dissociation.

A variety of ion traps are used in mass spectrometry. A key feature shared by most of them is the ability to perform tandem mass spectrometry (MS/MS). The Orbitrap is perhaps the most notable ion trap in which MS/MS has yet to be performed.

Absorption mode Fourier transform electrostatic linear ion trap mass spectrometry.

In Fourier transform mass spectrometry, it is well-known that plotting the spectrum in absorption mode rather than magnitude mode has several advantages. However, magnitude spectra remain commonplace due to difficulties associated with determining the phase of each frequency at the onset of data acquisition, which is required for generating absorption spectra. The phasing problem for electrostatic traps is much simpler than for Fourier transform ion cyclotron resonance (FTICR) instruments, which greatly simplifies the generation of absorption spectra.

Nondestructive tandem mass spectrometry using a linear quadrupole ion trap coupled to a linear electrostatic ion trap.

A novel hybrid tandem mass spectrometer is presented that combines a linear quadrupole ion trap (QLIT) with a linear electrostatic ion trap (ELIT), which is composed of opposing ion mirrors. The QLIT is used both as an accumulation device for the pulsed injection of ions into the ELIT and as a collision cell for ions released from the ELIT and back into the QLIT. Ions are subjected to mass analysis in the ELIT via Fourier transformation of the time-domain signal obtained from an image current measurement using a pick-up electrode in the field-free region of the ELIT.

Adaptation of a 3-D quadrupole ion trap for dipolar DC collisional activation.

Means to allow for the application of a dipolar DC pulse to the end-cap electrodes of a three-dimensional (3-D) quadrupole ion trap for as short as a millisecond to as long as hundreds of milliseconds are described. The implementation of dipolar DC does not compromise the ability to apply AC waveforms to the end-cap electrodes at other times in the experiment. Dipolar DC provides a nonresonant means for ion acceleration by displacing ions from the center of the ion trap where they experience stronger rf electric fields, which increases the extent of micro-motion.

Saturation transfer double-difference NMR spectroscopy using a dual solenoid microcoil difference probe.

An experiment designed to collect a saturation transfer double difference (STDD) NMR spectrum using a solenoid microcoil NMR difference probe is reported. STDD-NMR allows the investigation of ligand-biomolecule binding, with moderate concentration requirements for unlabeled molecular targets and the ability to discern binding events in the presence of non-binding ligands. The NMR difference probe acquires the signals from two different samples at once, and cancels common signals automatically through a mechanism of switching between parallel excitation and serial acquisition of the sample signals.

Results with an apparatus for pressurized planar electrochromatography.

Pressurized planar electrochromatography (PPEC) is a fast and efficient planar chromatographic technique. The mobile phase is driven by electroosmotic flow, while the system is pressurized in a manner that allows heat to flow between the sorbent layer and the pressurizing medium. The reproducibility of solute retention was not satisfactory in the initial report describing PPEC.

NMR difference spectroscopy with a dual saddle-coil difference probe.

A new difference probe for nuclear magnetic resonance (NMR) spectroscopy is presented. The difference probe uses two saddle-shaped coils to excite and detect two samples simultaneously. The samples are held in a specially modified 3-mm NMR tube with an Ultem plastic disk to separate the samples.

Apparatus and initial results for pressurized planar electrochromatography.

Pressurized planar electrochromatography (PPEC) is a new planar chromatographic technique in which the mobile phase is driven by electroosmotic flow, while the sorbent layer is pressurized in a manner that allows heat to flow from the layer through an electrically insulating, thermally conducting, sheet of aluminum nitride ceramic. A prototype apparatus for performing PPEC is described. Separation by PPEC is faster than by conventional TLC, and an example is presented of a 24-fold enhancement in the speed of separation.

NMR difference probe: a dual-coil probe for NMR difference spectroscopy.

A unique probe designed to acquire nuclear magnetic resonance difference spectra of two samples is presented. The NMR Difference Probe contains two sample coils in a resonant circuit that switches between parallel excitation and serial acquisition to cancel common signals such as solvent peaks and impurities. Two samples containing a common analyte, acetonitrile, were used to demonstrate signal cancellation in a difference spectrum collected with a single pulse experiment.