In one aspect, a method of calibrating a Fourier Transform (FT) multipole mass spectrometer is disclosed, which comprises measuring a plurality of secular frequencies of a calibrant ion in a multipole FT mass analyzer for a plurality of RF voltages (V.sub.RF) applied to at least one rod of the multipole mass analyzer adjusted q analyzer, calculating Mathieu β and q parameters for each of 5 the measured secular frequencies, and determining RF voltage amplitude (V.sub.RF) for each calculated q parameter. For each calculated q parameter, an offset RF voltage amplitude (ΔV.sub.RF) corresponding to a deviation of the applied V.sub.RF and the calculated V.sub.RF is determined so as to generate a ΔV.sub.RFv.s. q calibration curve.

The invention relates to reducing harmonic signals in FT-ICR spectra. Since harmonic signals in quadrupolar 2ω-detection can be more abundant for the same ion motion in the ICR cell as compared to harmonic signals in classical dipolar 1ω-detection, they could hitherto not be reduced to satisfactory levels by any known method, such as gated deflection during ion introduction into, and correcting for an offset electric field axis in the ICR cell. The present disclosure foresees, in addition to other methods carried out for improving the measurement conditions as the case may be, performing the quadrupolar 2ω-detection at least twice, where the phase of the ion excitation radio frequency is turned by 180° in the second measurement. From the sum transient, a Fourier-transformed spectrum is derived. As a result, the broad band spectra of complex substance mixtures like crude oil become cleaner, and misinterpretations of false (harmonic) peaks are minimized.

The invention relates to reducing harmonic signals in FT-ICR spectra. Since harmonic signals in quadrupolar 2ω-detection can be more abundant for the same ion motion in the ICR cell as compared to harmonic signals in classical dipolar 1ω-detection, they could hitherto not be reduced to satisfactory levels by any known method, such as gated deflection during ion introduction into, and correcting for an offset electric field axis in the ICR cell. The present disclosure foresees, in addition to other methods carried out for improving the measurement conditions as the case may be, performing the quadrupolar 2ω-detection at least twice, where the phase of the ion excitation radio frequency is turned by 180° in the second measurement. From the sum transient, a Fourier-transformed spectrum is derived. As a result, the broad band spectra of complex substance mixtures like crude oil become cleaner, and misinterpretations of false (harmonic) peaks are minimized.

In one aspect, a mass spectrometer is disclosed, which comprises a Fourier Transform (FT) mass analyzer having an input port for receiving ions and an exit port through which the ions exit the FT mass analyzer, a detector disposed downstream of said FT analyzer for detecting ions exiting the FT analyzer, and a multi-segment ion guide having a plurality of segments, said multi-segment ion guide being disposed upstream of said FT mass analyzer and having an input port for receiving ions and an output port through which ions exit the FT mass analyzer. The segments of the ion guide are configured to be independently activated via application of a DC offset voltage thereto so as to adjust a length through which ions passing through the ion guide experience collisional cooling.

A method of carrying out mass spectrometry, comprising: using an electrostatic or electrodynamic ion trap to contain a plurality of ions, each ion having a mass to charge ratio, the ions having a first plurality of mass to charge ratios, each ion following a path within the electrostatic or electrodynamic ion trap having a radius; and for each of a second plurality of the mass to charge ratios: modulating the radii of the ions in a mass to charge ratio-dependent fashion dependent upon the mass to charge ratio; fragmenting the ions thus modulated in a radius-dependent fashion; and determining a mass spectrum of the ions.

A method of carrying out mass spectrometry, comprising: using an electrostatic or electrodynamic ion trap to contain a plurality of ions, each ion having a mass to charge ratio, the ions having a first plurality of mass to charge ratios, each ion following a path within the electrostatic or electrodynamic ion trap having a radius; and for each of a second plurality of the mass to charge ratios: modulating the radii of the ions in a mass to charge ratio-dependent fashion dependent upon the mass to charge ratio; fragmenting the ions thus modulated in a radius-dependent fashion; and determining a mass spectrum of the ions.

A system, method and computer program product are provided for calculating one or more indicative properties, e.g., one or more of the cetane number, octane number, pour point, cloud point and aniline point of oil fractions, from the density and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) of a sample of an oil sample.

A system, method and computer program product are provided for calculating one or more indicative properties, e.g., one or more of the cetane number, octane number, pour point, cloud point and aniline point of oil fractions, from the density and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) of a sample of an oil sample.

Methods and systems for analyzing ions in a magnetic ion trap are provided herein. In accordance with various aspects of the present teachings, the methods and systems described herein enable Fourier transform ion cyclotron resonance mass spectrometry across relatively narrow gap magnetic fields substantially perpendicular to the axis along which the ions are injected into the ion trap. As a result, smaller, less expensive magnets can be used to produce the high-intensity, uniform magnetic fields utilized in high performance FT-ICR/MS applications. Accordingly, the present teachings enable permanent magnets (as well as electromagnets) to generate these magnetic fields, potentially reducing the cost, size, and/or complexity of the systems described herein relative to conventional FT-ICR systems.

Methods and systems for analyzing ions in a magnetic ion trap are provided herein. In accordance with various aspects of the present teachings, the methods and systems described herein enable Fourier transform ion cyclotron resonance mass spectrometry across relatively narrow gap magnetic fields substantially perpendicular to the axis along which the ions are injected into the ion trap. As a result, smaller, less expensive magnets can be used to produce the high-intensity, uniform magnetic fields utilized in high performance FT-ICR/MS applications. Accordingly, the present teachings enable permanent magnets (as well as electromagnets) to generate these magnetic fields, potentially reducing the cost, size, and/or complexity of the systems described herein relative to conventional FT-ICR systems.