Abstract:
A mass spectrometer is disclosed comprising a Time of Flight mass analyser comprising an ion detector comprising an Analogue to Digital Converter. Signals from the Analogue to Digital Converter are digitised and the arrival time and intensity of ions are determined. The arrival time T0 and intensity S0 of each ion arrival event is converted into two separate intensities S(n),S(n+i) which are stored in neighbouring time bins T(n), T(n+1).
Abstract:
A mass spectrometer is disclosed comprising an ion mobility spectrometer or separator (3) arranged upstream of a collision or fragmentation cell (5). Ions are separated according to their ion mobility within the ion mobility spectrometer or separator (3). The kinetic energy of the ions exiting the ion mobility spectrometer or separator (3) is increased substantially linearly with time in order to optimize the fragmentation energy of ions as they enter the collision or fragmentation cell (5).
Abstract:
A closed-loop ion guide (1) is disclosed comprising a plurality of electrodes having apertures through which ions are transmitted in use. Ions are injected into the closed-loop ion guide (1) and may make several circuits of the closed-loop ion guide (1) before being ejected from the ion guide (1). In a mode of operation the ion guide (1) may be arranged to separate ions temporally according to their ion mobility.
Abstract:
A closed-loop ion guide is disclosed comprising a plurality of electrodes having apertures through which ions are transmitted in use. Ions are injected into the closed-loop ion guide and may make several circuits of the closed-loop ion guide before being ejected from the ion guide. In a mode of operation the ion guide may be arranged to separate ions temporally according to their ion mobility.
Abstract:
A mass spectrometer is disclosed comprising a first ion trap or ion guide (2), a single ion mobility spectrometer or separator stage (3) and a second ion trap or ion guide (4) arranged downstream of the ion mobility spectrometer or separator (3). In a mode of operation ions from the second ion trap or ion guide (4) are passed from the second ion trap or ion guide back upstream to the ion mobility spectrometer or separator (3).
Abstract:
A method of detecting one or more compounds, chemicals or contaminants in a substrate by mass spectrometry is disclosed. A non-living substrate is analysed by contacting the substrate with a diathermy knife. An electric current is applied to the diathermy knife such that the diathermy knife vaporises a portion of the substrate. The vapour is aspirated via a sampling tube pumped by a venturi pump into a vacuum chamber of a mass spectrometer. Analyte molecules are aspirated into the vacuum chamber whereupon they impact a surface of the vacuum chamber and are ionised to form analyte ions which are then mass analysed.
Abstract:
An ion guide or ion trap is disclosed having an entrance electrode and an exit electrode. The potential of the exit electrode is periodically dropped for a relatively short period of time allowing some ions to escape from the ion guide or ion trap via an aperture in the exit electrode. The period of time that the potential of the exit electrode is dropped for is progressively increased and ions emerge from the ion guide or ion trap in a mass to charge ratio dependent manner. The ion guide or ion trap may be operated as a mass separator or low resolution mass analyzer.
Abstract:
A method of mass spectrometry is disclosed wherein a signal output from an ion detector is digitised by an Analogue to Digital Converter and is then deconvoluted to determine one or more ion arrival times and one more ion arrival intensities. The process of deconvoluting the ion signal involves determining a point spread function characteristic of an ion arriving at and being detected by the ion detector. A distribution of ion arrival times which produces a best fit to the digitised signal is then determined given that each ion arrival is assumed to produce a response given by the point spread function. A plurality of ion arrival times are then combined to produce a composite ion arrival time-intensity spectrum.
Abstract:
A mass spectrometer is disclosed comprising a device which is operable in a first mode of operation to separate ions temporally according to their ion mobility by applying a continuous axial electric field. The device is also operable in a second mode of operation wherein ions are separated temporally according to the their mass to charge ratio by pulsing an applied axial electric field ON and OFF.
Abstract:
A method of screening a sample for the presence of one or more known compounds of interest is disclosed. A fragmentation device is repeatedly switched between a fragmentation mode of operation and a non-fragmentation mode of operation. A determination is made whether a candidate parent ion of interest is present in a non-fragmentation data set and whether one or more corresponding fragment ions of interest are present in a fragmentation data set. A further determination is made to check if the candidate parent ion of interest and the one or more corresponding fragment ions of interest have substantially similar elution or retention times and/or ion mobility drift times.