Originally published in R&D Magazine, September, 2006
Mass spectrometers have become the analytical method of choice among researchers looking to characterize proteomics, metabolomics, or any structural analysis where determining the elemental composition of a material is needed. Researchers at Thermo Electron Corp., Bremen, Germany, have developed a hybrid linear ion trap mass spectrometer, the LTQ Orbitrap, that advances the state-of-the-art with its high mass accuracy, high sensitivity, and good dynamic range. The device combines patented Orbitrap technology with Thermo’s well established LTQ linear ion trap to enable faster, more sensitive, and more reliable detection and identification of compounds in complex mixtures.
In the Orbitrap, ions to be analyzed are electrostatically trapped in an orbit around a central, spindle-shaped electrode. The electrode confines these ions so that they both orbit around the central electrode and oscillate back and forth along the central electrode’s long axis. This oscillation generates an image current in the detector plates, which is then recorded by the instrument. The resulting mass resolution is greater than 100,000 compared to just 20,000 in a competitive QTOF (quadrupole time-of-flight) instrument. It’s mass accuracy is better than 5 ppm with external calibration, compared to more than 5 ppm for the Q-TOF. It enables accurate mass measurements over a dynamic range that matches or exceeds the spread of signal intensities in the electrospray ion source.