摘要:
Methods and devices for detecting a target substance on a subject without contacting the subject are disclosed. At least one air jet blows analyte from a surface of the subject into an airflow, the airflow entraining the analyte. A desorption channel desorbs molecules from analyte in a portion of the airflow travelling through the desorption channel. An ionizer forms ions from vapor molecules in the portion of the airflow. At least one mass spectrometer analyzes the ions to detect the target substance. The flow travels without interruption from the subject to the at least one mass spectrometer. The desorption channel causes a sufficient quantity of molecules to desorb from the analyte to enable the at least one mass spectrometer to detect the target substance.
摘要:
This invention relates to a method and apparatus for separation of rare stable or radioactive isotopes from their atomic or molecular isobars in mass spectrometry (MS). In the present invention, the approach taken to removing atomic isobars utilizes a high transmission device for decelerating ions in combination with low energy reactions, such as ion-molecule reactions or near resonant electron transfer, in RF ion guides. The isobar is selectively depleted by electron transfer or other reactions between negative ions and gaseous targets in pressurized RF ion guides at low energies. The energy is controlled in such a way as to prevent reaction of the ion of interest while inducing reactions with the undesired isobar interference. The technique is of particular relevance to accelerator mass spectrometry (AMS) for which it allows substantial reductions in the necessary terminal voltage. The effect is to allow reductions in the size and cost of AMS installations.
摘要:
A mass spectrometer interface, having improved sensitivity and reduced chemical background, is disclosed. The mass spectrometer interface provides improved desolvation, chemical selectivity and ion transport. A flow of partially solvated ions is transported along a tortuous path into a region of disturbance of flow, where ions and neutral molecules collide and mix. Thermal energy is applied to the region of disturbance to promote liberation of at least some of the ionized particles from any attached impurities, thereby increasing the concentration of the ionized particles having the characteristic m/z ratios in the flow. Molecular reactions and low pressure ionization methods can also be performed for selective removal or enhancement of particular ions.
摘要:
A method and an apparatus for selectively transmitting ions produced by an inductively coupled plasma ionization technique is disclosed. Ions produced within the plasma source are provided to a FAIMS analyzer within a low pressure chamber of a mass spectrometer and in fluid communication with the plasma source for receiving ions therefrom. The ions are separated in FAIMS and at least some of the ions are provided to the mass spectrometer after separation.
摘要:
A mass spectrometer system in which ions are mass selected in an RF-only quadrupole at relatively high pressure (1 to 7 torr) using FNF or SWIFT, and are then fragmented in a following collision cell which is in the same vacuum chamber, thus reducing pumping needs. The fragments can be mass analyzed in any desired way, including by another RF-only quadrupole in the same vacuum chamber and also using FNF or SWIFT. Triple MS can be performed in the same way.
摘要:
An ion guide includes multiple stages. An electric field within each stage guides ions along a guide axis. Within each stage, amplitude and frequency, and resolving potential of the electric field may be independently varied. The geometry of the rods maintains a similarly shaped field from stage to stage, allowing efficient guidance of the ions along the axis. In particular, each rod segment of the ith of stage has a cross sectional radius ri, and a central axis located a distance Ri+ri from the guide axis. The ratio ri/Ri and is substantially constant along the guide axis, thereby preserving the shape of the field.
摘要:
An ion source and method for providing ionized particles to a molecular/atomic analyser, such as a mass spectrometer, are disclosed. The ion source includes a vessel defining a channel; a gas inlet extending from the gas source into the channel, for introducing a gas flow into the channel; a sample inlet extending into the channel for introducing sample within the channel; and an ionizer to ionize the sample in the channel. The vessel is sufficiently sealed to allow the channel to be pressurized, at a pressure in excess of 100 Torr. At least one gas source maintains the pressure of the channel at a pressure in excess of 100 Torr and the pressure exterior to the channel at a pressure in excess of 0.1 Torr and provides a gas flow that sweeps across the ionizer to guide and entrain ions from the ionizer to the outlet.
摘要:
An ion guide includes multiple stages. An electric field within each stage guides ions along a guide axis. Within each stage, amplitude and frequency, and resolving potential of the electric field may be independently varied. The geometry of the rods maintains a similarly shaped field from stage to stage, allowing efficient guidance of the ions along the axis. In particular, each rod segment of the ith of stage has a cross sectional radius ri, and a central axis located a distance Ri+ri from the guide axis. The ratio ri/Ri and is substantially constant along the guide axis, thereby preserving the shape of the field.
摘要:
An ion detector includes collision surfaces for converting both positively and negatively charged ions into emitted secondary electrons. Secondary electrons may be detected using an electron detector, than may, for example include an electron multiplier. Conveniently, secondary electrons (or electrons emitted by the multiplier) may be detected using an electron pulse counter.
摘要:
A mass spectrometer interface, having improved sensitivity and reduced chemical background, is disclosed. The mass spectrometer interface provides improved desolvation, chemical selectivity and ion transport. A flow of partially solvated ions is transported along a tortuous path into a region of disturbance of flow, where ions and neutral molecules collide and mix. Thermal energy is applied to the region of disturbance to promote liberation of at least some of the ionized particles from any attached impurities, thereby increasing the concentration of the ionized particles having the characteristic m/z ratios in the flow. Molecular reactions and low pressure ionization methods can also be performed for selective removal or enhancement of particular ions.