Introduction of samples into a mass spectrometer

Details Introduction of samples into a mass spectrometer Introduction of samples into a mass spectrometer

1985-07-19

1987-01-06

Fields, Carolyn E.

Radiant energy

Ionic separation or analysis

With sample supply means

250288, 7386482, 7386485, 414417, H01J 4904

Patent

active

046348670

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to the introduction of samples into the inlet system of a mass spectrometer.
The usefulness of mass spectrometry in analysis has long been recognised but the technique has hitherto suffered from the severe drawback that each analysis took a considerable time because the introduction of each sample called for the vacuum chamber to be opened. Before analysis could commence, the vacuum conditions needed to be re-established and in order to reduce the quantity of air entering the system with each sample, a series of locks were employed at the inlet system. The analysis therefore needed to be performed by skilled technicians with the result that mass spectrometers were regarded as specialised laboratory equipment rather than, for example, as apparatus to be used in quality control of mass produced products, where analyses need to be performed on a frequent and regular basis.
In No. GB-A-2,141,230 there is described an inlet system for a pyrolysis mass spectrometer in which the above disadvantage is considerably mitigated allowing a complete analysis of a sample to be performed in only a very few minutes. A sample container is offered to an aperture in the inlet system. The inlet system rapidly evacuates the container, pyrolyses the sample and establishes communication between the container and the vacuum chamber of the mass spectrometer to enable the sample to be analysed.
The present invention is concerned with the feeding of samples to such an inlet system in such a manner as to take advantage of the inherent speed of operation of the mass spectrometer and enable the process of analysis to be further automated.
According to a first aspect of the present invention, there is provided a method of introducing a sample for analysis into the inlet system of a mass spectrometer, the method comprising placing the sample in a tube open at only one end, placing around the tube an O-ring which is free to slide along the outer wall of the tube, placing the sample tube with its open end adjacent an aperture of the inlet system of the mass spectrometer applying an axially directed force to the O-ring to compress the O-ring into radial sealing engagement with the outer wall of the tube and axial sealing engagement with the inlet system of the mass spectrometer, the sample tube upon evacuation by the inlet system of the mass spectrometer forming part of the vacuum retaining wall.
According to a second aspect of the invention, there is provided a sample tube for a mass spectrometer comprising a tube open at only one end for receiving a sample and an O-ring surrounding the tube and slidable along the outer surface of the tube, the O-ring being compressible about the tube to seal the open end of the tube against an inlet aperture of the mass spectrometer, whereby in use the sample tube forms part of the vacuum retaining wall of the spectrometer.
Preferably, a boat is arranged within the tube for receiving the sample to be analysed, the boat being of a material capable of being heated by an induction coil surrounding the sample tube, to enable the sample to be pyrolysed.
Conveniently, the boat is V-shaped in cross section and is held in position within the tube by virtue of the upper edges of the limbs being resiliently urged against the inner wall of the tube, the trough of the boat being spaced from the inner wall of the tube.
The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a section through a sample feed system for a mass spectrometer,
FIG. 2 is a partial plan view of the sample magazine used in the feed system of FIG. 1, and
FIG. 3 is a section through a sample tube fitted with a boat and an O-ring.
In FIG. 1, there is shown at 10 part of the inlet system of a mass spectrometer. The inlet system 10 is not shown in detail but is preferably as described in GB-A-2,141,230, which is imported herein by reference. For the purposes of the present application, it sufficies to know that the inlet system 10 has an aperture 12

REFERENCES:
patent: 3440417 (1969-04-01), Heath
patent: 3449563 (1969-06-01), Brown
patent: 4076982 (1978-02-01), Ritter et al.
patent: 4405860 (1983-09-01), Brunnee et al.

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