Provided are methods for determining the apolipoprotein E (ApoE) phenotype in a sample by mass spectrometry; wherein the ApoE allele(s) present in the sample is determined from the identity of the ions detected by mass spectrometry. In another aspect, provided herein are methods for diagnosis or prognosis of Alzheimer's disease or dementia.

A quadrupole mass spectrometer includes: a quadrupole mass filter with four rod electrodes arranged so as to surround a central axis; and a magnet that forms a magnetic field in at least a part of an inside of the quadrupole mass filter in a direction intersecting the central axis.

An apparatus and a method of data independent combined ion mobility and mass spectroscopy analysis includes introducing precursor ions into an ion mobility spectrometer (IMS), sequentially releasing precursor ions from said IMS according to their ion mobility, introducing said released precursor ions into a mass filter, fragmenting the precursor ions transmitted through said mass filter to generate fragment ions, and carrying out a mass spectroscopy measurement on said fragment ions. The IMS and mass filter are controlled in a synchronized manner to carry out a plurality of IM scans, wherein adjacent mass windows in said IM scan that are associated with consecutive mass spectroscopy measurements of fragment ions overlap, such that precursor ions transmitted through said mass filter during said IM scan are located in at least one continuous scan region in an m/z-IM plane which extends in a generally diagonal direction in said m/z-IM plane.

Control of an amplitude of a signal applied to a component of a mass spectrometer is described. In one aspect, a mass spectrometer includes a component and a resonant circuit to generate a radio frequency (RF) signal applied to the component. An amplitude control circuit can be inductively coupled with inductors of the resonant circuit to selectively discharge energy from the resonant circuit and, therefore, adjust the amplitude of the signal in particular situations.

Systems and methods are provided for shaping an effective transmission window used to select precursor ions for a precursor mass range of a sequential windowed acquisition experiment. For at least one precursor mass range, an ion transfer function is selected that is a function of mass using a processor. A quadrupole mass filter that transmits ions from a sample is instructed to produce two or more transmission windows over time using the processor. The two or more transmission windows are produced to cumulatively create an effective transmission window for the at least one precursor mass range with a shape described by the ion transfer function.

A dwell time calculation table (51a) showing a correspondence relation between a CID gas pressure inside a collision cell (31) and a dwell time for data collection is stored in a processing condition parameter memory (51) of a controller (50). In the table (51a), as the CID gas pressure becomes higher, the dwell time becomes longer. When an instruction to execute an MRM measurement mode is given, the controller (50) determines the dwell time in accordance with the currently set CID gas pressure, and controls a data collector (41) to accumulate detection signals from an ion detector (34) during the determined dwell time and obtain the accumulated value. If the CID gas pressure inside the collision cell (31) is high, a decrease in ion speed becomes remarkable, and the rising of the ion intensity becomes slow. However, if the dwell time becomes long, influences of the slow rising on the accumulated value are relatively reduced, and the accuracy of the accumulated value is enhanced. Accordingly, the quantitative accuracy can be enhanced.

There is provided a gas analyzer apparatus that analyzes inflowing sample gas. The gas analyzer apparatus includes a filter unit that filters the sample gas, a detector unit that detects the result of filtering, a housing that houses these elements, and a control unit that controls the respective potentials of these elements. The control unit includes a cleaning control unit that sets the respective potentials of the filter unit, the detector unit, and the housing to cleaning potentials that draws in, as plasma for cleaning purposes, process plasma from a source that supplies the sample gas or plasma generated by a plasma generation unit.

Method for producing multiply-charged helium nanodroplets and charged dopant clusters and nanoparticles out of the helium nanodroplets, the method comprising: producing neutral helium nanodroplets in a cold head (1) via expansion of a pressurized, pre-cooled, supersonic helium beam of high purity through a nozzle (3) into high vacuum with a base pressure under operation preferably below 20 mPa, ionizing the helium nanodroplets by electron impact (15), wherein the electron impact (15) leads to multiply-charged helium nanodroplets, doping the charged helium nanodroplets with dopant vapor in the pickup cell (19), wherein the doped nanodroplets form cluster ions with the initial charges acting as seeds, wherein the size of the nanoparticles can vary from a few atoms up to 105 atoms by arranging the size of the neutral helium nanodroplets, the charge of the helium nanodroplets and the density of dopant vapor in the pickup cell (19).

A method of mass filtering ions is disclosed comprising: providing a first, AC-only, mass filter (2); providing a second mass filter (4) downstream of the first mass filter; applying a first AC voltage (8) to electrodes of the first mass filter so as to radially confine ions between the electrodes, and applying a second AC voltage (10) between electrodes of the first mass filter (2) so as to radially excite some of said ions such that these ions are not transmitted; and using the second mass filter (4) to mass filter ions; wherein at any given time the second mass filter (4) only transmits ions having a first range of mass to charge ratios and filters out all other ions; and wherein the step of applying the at least one second AC voltage (10) to electrodes of the first mass filter (2) radially excites ions such that at least some ions having mass to charge ratios above said first range are not transmitted into the second mass filter.

In a mass spectrometry method for generating product ions from a precursor ion derived from a sample component having a hydrocarbon chain and mass-analyzing the product ion, the precursor ion is irradiated with an oxygen radical or a hydroxy radical and a nitrogen oxide radical to generate product ions, the product ions are separated according to mass-to-charge ratio and the product ions are detected, and a structure of the hydrocarbon chain is inferred based on mass-to-charge ratio of the detected product ions.