Abstract: In its most general terms the invention compensates for the effect of the mass offset in the prior art calibration method. This can be achieved either by correcting for the offset or assigning mass to the peaks in such a way that the offset is avoided. Accordingly in a first aspect there is provided a method of calibrating a reflectron time-of-flight mass spectrometer using a spectrum generated by fragment ions wherein a measured mass value is modified to take account of the effect of post source decay and that modified value is used for calibration. A modified calibration function can then be defined and used to determine actual fragment ion masses of an unknown compound.

Abstract: A time of flight (TOF) mass spectrometer includes an ion source which has an extraction lens. The extraction lens has an element with an aperture. The aperture extends through the element to form a through-channel. In use, ions may pass from one side of the element to the opposite side of the element by passing through the through channel. The through channel has a length which is equal to or greater than 8/10 of a diameter of the aperture.

Abstract: A time of flight (TOF) mass spectrometer includes an ion source which has an extraction lens. The extraction lens has an element with an aperture. The aperture extends through the element to form a through-channel. In use, ions may pass from one side of the element to the opposite side of the element by passing through the through channel. The through channel has a length which is equal to or greater than {fraction (8/10)} of a diameter of the aperture.

Abstract: A time of flight (TOF) mass spectrometer includes an ion source which has an extraction lens. The extraction lens has an element with an aperture. The aperture extends through the element to form a through-channel. In use, ions may pass from one side of the element to the opposite side of the element by passing through the through channel. The through channel has a length which is equal to or greater than {fraction (8/10)} of a diameter of the aperture.

Abstract: In its most general terms the invention compensates for the effect of the mass offset in the prior art calibration method. This can be achieved either by correcting for the offset or assigning mass to the peaks in such a way that the offset is avoided. Accordingly in a first aspect there is provided a method of calibrating a reflectron time-of-flight mass spectrometer using a spectrum generated by fragment ions wherein the mass of the fragment ion is assigned using the mono-isotopic peak only. In other words a value corresponding to the mass of the fragment ion used for calibration is assigned using the fragment ion mono-isotopic peak only and said value is used to calibrate the spectrometer.

Abstract: In its most general terms the invention compensates for the effect of the mass offset in the prior art calibration method. This can be achieved either by correcting for the offset or assigning mass to the peaks in such a way that the offset is avoided. Accordingly in a first aspect there is provided a method of calibrating a reflectron time-of-flight mass spectrometer using a spectrum generated by fragment ions wherein a measured mass value is modified to take account of the effect of post source decay and that modified value is used for calibration. A modified calibration function can then be defined and used to determine actual fragment ion masses of an unknown compound.

Abstract: In a first aspect there is provided an extraction lens for a TOF mass spectrometer ion source, said lens including an element having an aperture, said aperture extending through the element so as to form a through channel, such that, in use, ions may pass from one side of the element to the opposite side of the element by passing through said through channel; characterised in that said through channel has a length equal to or greater than 8/10 of the diameter of said aperture.

Abstract: In its most general terms the invention compensates for the effect of the mass offset in the prior art calibration method. This can be achieved either by correcting for the offset or assigning mass to the peaks in such a way that the offset is avoided. Accordingly in a first aspect there is provided a method of calibrating a reflectron time-of-flight mass spectrometer using a spectrum generated by fragment ions wherein the mass of the fragment ion is assigned using the mono-isotopic peak only. In other words a value corresponding to the mass of the fragment ion used for calibration is assigned using the fragment ion mono-isotopic peak only and said value is used to calibrate the spectrometer.