US3014128A - Sample introduction system for vacuum apparatus - Google Patents

Description

Dec. 19, 1961 R. TAUBERT 3,014,128

SAMPLE INTRODUCTION SYSTEM FOR VACUUM APPARATUS Filed Sept. 25, 1959 INVENTOR. ROLF TAUBERT ATTORNEYS United States Patent SAMPLE INTRODUCTION SYSTEM FOR VACUUM APPARATUS Rolf Taubert, Braunschweig, Germany, assignor to Atlas- Werke Aktiengesellschaft, Bremen, Germany Filed Sept. 25, 1959, 'Ser. No.842,432 Claims priority, application Germany Oct. 1, 1958 9 Claims. (Cl. 250-419) This invention relates to a sample introduction system for use together with vacuum apparatus e.g. mass spectrometers.

For these purposes some other inlet systems, for example mercury covered disks of vitreous porcelain, mercury filled nozzles and glass cartridges are well known and in use.

Conventional type systems as indicated herein before have some important disadvantages in so far as the sample is subject to partial vaporizing, as said mercury nozzles cannot be heated and as the use of glass cartridges is complicated for the operator.

The invention as described below avoids these disadvantages by use of a capillary tube which is extended at one end in such a manner that this extension forms a reservoir whereas the other end is fitted to the vacuum apparatus and may be shut at will by aid of an adjustable Teflon diaphragm. The inlet system according to the invention does not comprise any mercury, the fluid gets only in contact with materials e.g. glass, Teflon and stainless steel which are not attacked by it.

Owing to this arrangement the fluid enters free of air bubbles into the lower part of the sample introduction system. Such a system comprises moreover a heating device which renders possible to fill in fluids of a difiicult volatility.

The amount of fluid to be filled into the system is defined by the volume of the capillary portion between the two markings on the outside of the capillary tube.

The foregoing and other objects and features of my invention will be apparent from or will be referred to in the following description of the embodiments of my invention as specified in the drawing in which FIG. 1 is a part cross section drawing of the sample introduction system to which the invention relates,

FIG. 2 is a cross section drawing of a somewhat altered sample introduction system according to the invention.

Regarding FIG. 1 the glass capillary 1 having an inside diameter of about 0.1 mm. and a length of about 150 mm. is sealed high vacuum tight by aid of a valve flange or dome 2 and a Teflon collar 3 to the valve casing 4 having a cylindrical cavity in such a manner that the lower orifice of said glass capillary fits the cylindrical cavity 5 of said valve casing. This cavity is closed at its lower end by aid of a diaphragm 6. The latter is stretched and fixed to the valve casing by aid of a flange 7 and its middle portion is pressed on the lower orifice 14 of the glass capillary by aid of a knurled screw 8. By turning this screw an operator is able to close or to open said orifice at will.

FIG. 2 illustrates further another executed example of a sample introduction system according to the invention in detail.

As described herein before this sample introduction system comprises also a capillary 1 fitted to the valve casing 4 by aid of a gasket .13 and a flange 15 supported by bolts 16 and 17. Axial displacement of the capillary is prevented by aid of a spherical shaped portion 24 of said capillary. Said spherical shaped portion fits close to the conical shaped inner surface 19 of the valve casing 4.

This valve casing 4 is connected via a tube 22 to the analyzing equipment. The lower orifice 14 of the capillary 1 can be shut or opened at will by stretching or 3,014,128 Patented Dec. 19., 1961 loosening the membrane 6 in turning the screw 8 which fits in a flange 7 in clockwise or counterclockwise direction respectively. Loosening of the membrane 6 flS prevented by the helical spring 20 and a cylindrical spacer 21 working together with the screw 8 and a plunger 23 fitted to said screw "at .its top end. The operation of the sample introduction system can be further described as follows:

During normal use of the sample introduction system the apparatus, as described above, is fitted to the inlet system of the mass spectrometer by means of a flange 10. The capillary section remains closed. The system is now evacuated by aid of a pre-pump. Now a glass pipette containing a defined quantity of the sample to be analyzed is placed on the upper orifice 13 of said glass capillary section whereupon the lower orifice 14 of said capillary section is opened by turning the knurled screw in a counter-clockwise direction.

Due to the fact that the system is under vacuum the liquid is sucked into the capillary section. As soon as the capillary section is filled, the glass pipette is removed.

As soon as the liquid level has reached one of the upper markings 11 the lower orifice 14 of the capillary section is closed. Now the valve casing is evacuated again, the vacuum pump is then stopped and the inlet system is now connected via a valve to the spectrometers inlet system. By turning the knurled screw 8 the capillary is now opened again, the fluid is sucked into the lower portion of the capillary and evaporates at the inner walls of the valve casing, due to the fact that the casing is normally heated up by aid of heating fabrics 22' clamped to the outside of the valve casing.

As soon as the liquid level has reached one of the lower markings 11, the capillary is closed again.

It will be obvious to those skilled in the art upon a study of this disclosure that my invention permits of various modifications, other than those specially illustrated without departing from the essence of my invention and within the scope of the claims annexed hereto.

I claim as my invention:

1. A sample introduction system for use with analyzing equipment having an inlet, said system comprising a capillary, a valve casing provided with a recess connected with the inlet of said analyzing equipment, said capillary being fitted with its lower end in said recess, means for opening or closing the lower orifice of said capillary and also means for filling said capillary with the sample to be analyzed.

2. A sample introduction system, as defined in claim 1 and further comprising, a collar for fitting said capillary to said casing so that the casing encloses the lower part of said capillary.

3. A sample introduction system as defined in claim 1 wherein said capillary has a portion of greater thickness and spherical shape which fits close to a ring shaped surface at the inside of said valve casing.

4. A sample introduction system as set forth in claim 3 wherein said ring shaped surface is arranged at the inside of a dome closing said valve casing. p

'5. A sample introduction as set forth in claim 4 and further comprising, a gasket which is arranged in recesses of said domeand the inner wall of said ring shaped surmeans for opening or closing the lower orifice of said capillary; and means for filling said capillary with the liquid sample to be analyzed.

8, A sample introduction system in accordance with claim I wherein said means for opening or closing comprisesfa diaphragm selectively engageable with the lower end of said capillary to establish a fluid-tight seal between the opening in said capillary'and said valve-casing, spring means for urging said diaphragm away from said lower end, and an adjustable plunger pressing against said diaphragm below said lower end against the force of said spring means to selectively force said diaphragm into sealing contact with said lower end.

9. A sample introduction system in accordance with claim 8 wherein said spring means comprises, an annular spacer surrounding the lower end of said capillary tube and contacting said diaphragm, and a coil spring surrounding said capillary in compression between said spacer and the inside surface of said valve casing.

References Cited in the file of this patent UNITED STATES PATENTS 2,702,479 Black et a1 Feb. 22, 1955 2,712,399 Blears July 5, 1955

Images