A mass spectrometer comprises: an ion source that generates ions having an initial range of mass-to-charge ratios; an auxiliary ion detector, downstream from the ion source that receives a plurality of first ion samples derived from the ions generated by the ion source and determines a respective ion current measurement for each of the plurality of first ion samples; a mass analyzer, downstream from the ion source that receives a second ion sample derived from the ions generated by the ion source and to generate mass spectral data by mass analysis of the second ion sample; and an output stage that establishes an abundance measurement associated with at least some of the ions generated by the ion source based on the ion current measurements determined by the auxiliary ion detector.

An ion optical arrangement (1) for use in a mass spectrometer comprises a collision cell defining an ion optical axis along which ions may pass, electrodes comprising a set of parallel poles (11A, 11B, 11C) arranged in the collision cell, and a voltage source for providing voltages to the electrodes to produce electric fields. The ion optical arrangement is arranged for switching between a first operation mode in which the collision cell is pressurized and a second operation mode in which the collision cell is substantially evacuated. The ion optical arrangement is further arranged for producing a radio frequency electric focusing field in the first operation mode and a static electric focusing field in the second operation mode.

The present invention relates to the field of biomarkers. More specifically, the present invention relates to biomarkers useful in diagnosing brain injury or neurodegeneration. In one embodiment, a method for diagnosing brain injury in a patient comprises the steps of (a) obtaining a sample from the patient; (b) determining the ratio of citrullinated to unmodified arginine residues at one or more arginine residues of one or more brain injury biomarker proteins; and (c) correlating the ratio to a patient having brain injury or to a patient not having brain injury, thereby providing the diagnosis.

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.

Certain configurations described herein are directed to mass spectrometer systems that can use a gas mixture to select and/or detect ions. In some instances, the gas mixture can be used in both a collision mode and in a reaction mode to provide improved detection limits using the same gas mixture.

Lipid-derived ions captured within an ion trap are irradiated with hydrogen radicals to induce the reaction of hydrogen extraction (S1, S2). A precursor-ion isolation process is subsequently performed (S3), and the precursor ion is dissociated by low-energy collision-induced dissociation (S4). The thereby generated product ions are subjected to mass spectrometry to create a product-ion spectrum (S5, S6). Since the dissociation achieved by such a procedure does not cause hydrogen rearrangement, a peak pair having a mass difference of +12 Da characteristic of the unsaturated bond site certainly appears on the product-ion spectrum. By searching for this peak pair, the unsaturated bond site can be located (S7, S8). By such a method, a lipid-structure analysis including the determination of the position of the unsaturated bond site in a lipid can be performed in a stable and accurate manner without requiring derivatization or other cumbersome pretreatments.

Achieving high conversion of large multiply charged biological ions into low charge states involves requirements difficult to reconcile when high transmission and good spray quality (resulting in narrow mobility distributions) are sought. These multiple goals are achieved in this invention by partially isolating different regions from each other with electrostatic barriers relatively transparent to ions, such as metallic grids. One such region requires high electric fields for ion generation. The other region, used for ion recombination, is approximately field-free. In an alternative arrangement intended for charge reduction in sub-millisecond times, two sources of ions with opposite polarities are placed contiguously, with a grid in between. In all cases, ion crossing through grids into field free regions is effectively driven by space charge.

Provided is a mass spectrometer including a storage section in which an MRM measurement condition specifying an MRM transition and an execution time slot is stored for target compounds; an applied-voltage candidate value determiner for determining applied-voltage candidate values for each of the MRM transitions; a preliminary measurement number determiner for determining the number of times a preliminary measurement is performed to optimize an applied-voltage value in the plurality of MRM transitions; a unit measurement divider for dividing a plurality of unit measurements which correspond to all combinations of the MRM transitions and the applied-voltage values into the same number of groups as the number of times of the preliminary measurement, in such a manner as to minimize the number of overlaps of execution times; and a preliminary measurement execution file creator for creating a preliminary measurement execution file for each group.

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).

To reduce contamination of the apparatus with an additive and to quickly switch spraying and stopping of the additive, provided is an ion analyzer including: an ion source for ionizing a measurement target substance, a spray unit for atomizing and spraying toward the measurement target substance a liquid containing an additive that reacts with the measurement target substance; a separation analysis unit for separately analyzing an ion generated by a reaction between the measurement target substance and the additive; a detector for detecting the ion that has been separately analyzed by the separation analysis unit; and a control unit for lowering a flow rate of the additive supplied to the spray unit during a time when the additive is not necessary.