A mass spectrometer adopting a configuration of a multi-stage differential evacuation system appropriately performs optimization of a direct-current voltage applied to a plurality of ion optical elements for transporting ions. An auto-tuning controller acquires intensity data of ions derived from a predetermined component while changing a direct-current voltage applied to ion guides and the like, and searches for a direct-current voltage at which the intensity is maximized. When the direct-current voltage applied to a certain ion optical element is changed at the time of automatic adjustment, the direct-current voltage applied to all the ion optical elements thereafter is also changed by the same amount. Since the direct-current voltage difference between two adjacent ion optical elements always changes at only one point, the direct-current potential difference can be determined so as to optimize the ion passage efficiency.

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 method of operating a quadrupole device is disclosed. The method comprises operating the quadrupole device in a first mode of operation, wherein ions within a first mass to charge ratio range are selected and/or transmitted by the quadrupole device, and operating the quadrupole device in a second mode of operation, wherein ions within a second different mass to charge ratio range are selected and/or transmitted by the quadrupole device. In the first mode of operation, the quadrupole device is operated in a normal mode of operation wherein a main drive voltage is applied to the quadrupole device, or in a first X-band or Y-band mode of operation wherein a main drive voltage and two or more auxiliary drive voltages are applied to the quadrupole device. In the second mode of operation, the quadrupole device is operated in a second X-band or Y-band mode of operation wherein a main drive voltage and two or more auxiliary drive voltages are applied to the quadrupole device.

A time-of-flight mass spectrometer includes a flight tube, an ion introduction unit that is connected to the flight tube, an ion detector that detects an ion flown in the flight tube, and a control unit that controls the ion introduction unit and the flight tube, wherein: the control unit sequentially changes an accumulation state of the ion to be introduced into the flight tube by the ion introduction unit, for a plurality of measurement processes performed repeatedly.

A mass spectrometer includes an ion source configured to produce ions from a sample; a set of quadrupole rods configured to select ions based on a mass-to-charge ratio; a DC rod driver configured to produce a voltage; a DC rod driver filter configured to filter RF frequency interference; and a controller. The controller is configured to utilize the results of the constrained convex optimization to cause a DC rod drive to produce the DC filter input and provide a required voltage to the set of quadrupole rods, the constrained convex utilizing a impulse response curve of the DC rod driver filter to determine a DC filter input to achieve the required voltage on the set of quadrupole rods; select ions passing through the set of quadrupole rods based on the mass-to-charge ratio; and measure the intensity of the ions.

An ion detector (4) includes a shield electrode (42) between an aperture plate (41) and a conversion dynode (43). The shield electrode (42) has a rectilinearly-moving particle block wall (42a) positioned on an extension line (C′) extending from the central axis (C) of a quadrupole mass filter (3), and an ion attracting electric field adjustment wall (42b) inclined by a predetermined angle θ (acute angle) with respect to the extension line (C′). In the ion attracting electric field adjustment wall (42b) is provided an ion passing aperture (42c). The rectilinearly-moving particles, such as neutral particles, which are ejected from the quadrupole mass filter (3), are blocked by the rectilinearly-moving particle block wall (42a), thereby reducing noises caused by the rectilinearly-moving particles. Meanwhile, the potential of the ion attracting electric field adjustment wall (42b) corresponds to equipotential surfaces in a strong electric field formed by the conversion dynode (43), and thus the condition of the strong electric field is not remarkably changed from the state where no shield electrode (42) is provided. Therefore, the effect of drawing ions is exhibited, thereby maintaining the high ion-detection efficiency.

An ultrasonic transmitter (95) and detector (e.g., integrated as an ultrasound transducer) utilized in a feedback control system automatically monitors and/or detects surface profile (e.g., shape) of the liquid-air interface and adjusts the flow rate of sampling liquid to ensure that experimental conditions remain consistent at the time of sample introduction during serial samplings. The feedback control can provide for automated adjustment of the surface profile of the liquid-air interface in accordance with changes in desired set point according to an experimental workflow (e.g., automated adjustment between an interface corresponding to a vortex sampling set point and an overflow cleaning set point). Improvements in desorption efficiency and quality of mass spectrometry data by degassing of the liquid solvent utilized within the sampling interfaces, and/or utilization in a feedback control system for generating data indicative of a surface profile of the liquid-air interface within the interface's sampling port may be realized.

An analysis method includes: performing liquid chromatography using a mobile phase including an adsorption prevention agent for preventing adsorption of a sample including a compound having a phosphate group to metal; and performing mass spectrometry on an eluate of the liquid chromatography. The adsorption prevention agent includes an oxalic acid or a salt of the oxalic acid.

Control of an amplitude of a signal applied to rods of a quadrupole is described. In one aspect, a mass spectrometer includes an amplifier circuit that causes a radio frequency (RF) signal to be applied to the rods of the quadrupole based on an amplifier RF input signal. An analog-to-digital converter (ADC) can generate a digital representation of the RF signal. A controller circuit can receive the digital representation and adjust an amplitude of the amplifier RF input signal based on differences between an amplitude of a fundamental frequency of the RF signal being different than an expected amplitude.

Methods and systems for FTMS-based analysis having an improved duty cycle relative to conventional FTMS techniques are provided herein. In various aspects, the methods and systems described herein operate on a continuous ion beam, thereby eliminating the relatively long duration trapping and cooling steps associated with Penning traps or orbitraps of conventional FTMS systems, as well as provide increased resolving power by sequentially interrogating the continuous ion beam under different radially-confining field conditions.