Electricity: measuring and testing – Using ionization effects – For analysis of gas – vapor – or particles of matter
Patent
1988-12-01
1991-09-10
Wieder, Kenneth
Electricity: measuring and testing
Using ionization effects
For analysis of gas, vapor, or particles of matter
73 2802, 324459, 324 713, G01N 2762
Patent
active
050477234
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for detection of foreign matter in gases, in which method the gas and the foreign matter contained in it are ionized in an ionization zone.
For many different purposes, it is necessary to detect and to measure the contents of foreign matter contained in gases. In particular, when analyzing for very small quantities of foreign matter, the impurities of the gas may disturb the detection. In general, there are problems with the detection of different molecules or molecular groups in gases, as well as in gases attenuated by vacuum pumps or in vapour originating from evaporated solid or liquid materials. In particular there are difficulties in quickly and dependably detecting noxious gases contained in the atmosphere, such as from an industrial accident, or detecting never or other combat gases The principle method used today for analyzing such gases is the EC-detector of gas chromatographs, in which radioactive radiation is allowed to ionize the carrier gas and the molecules of the foreign matter contained in it. The ionized molecules of the carrier gas are permitted partly by means of delay to recombine themselves, after which the ions of the gas are measured. In such manner, for instance, there is obtained a signal indicative of organic substances evaporated into the carrier gas. Measuring devices based on this same principle have also been designed for analyzing nerve gases contained in the air. These devices are of two categories: in the first category the ionized molecules are led into a labyrinth, where the molecules of air are allowed to recombine themselves and the current of ions caused by organic molecules is thereafter measured. In the other category the entery of light air molecules into the ion measuring space is impeded by means of voltage grids. However, the method and the devices for carrying it out are not sufficiently sensitive for measuring low concentrations, such as nerve gases and the like in the air or they give a signal which may include other materials or impurities contained by the air, such as tobacco smoke, exhaust gases, explosion gases, protection smokes etc. Additionally, the a signal may be created by a sudden increase in the moisture content of the air, again giving an inaccurate result.
It is the purpose of the invention is to provid a method for detecting and measuring the quantity and quality of foreing matter contained in a gas. In particular, it is an object of the invention to provide a method of detecting very small amounts of a foreign substance even in the presence of other extraneous material in the gas.
SUMMARY OF THE INVENTION
The present invention in its broadest aspect relates to a method for the detection of foreign matter in gases, in which method the gas containing foreign matter is ionized in an ionization zone. The invention is characterized in that the ionized gas containing foreign matter are passed through chambers with different electric fields, and the field currents passing through two or more chambers are measured, and corresponding signals are obtained. The amounts and relationships of these signals provide an analysis of the foreign matter in the gases. An important feature of the invention is that the moving and recombinating ability of different molecules is taken advantage of in different electric fields, when the whole of the gas has initially been ionized in the ionization zone.
The method of the invention can be operated under atmospheric pressure or under vacuum. The method can also be used in many different chemical analyzing methods, such as in a detector of a gas chromatograph or in a detector of a liquid chromatograph, in which the materials are first heated or brought into a gaseous state by lowering the pressure. In such a way, the analyses may be carried out with higher resolution. With the help of the method in accordance with the invention it is also possible to measure concentrations from a desired group of materials and additionally divide the group into subdivisions, for instance in order to det
REFERENCES:
patent: 3679973 (1972-07-01), Smith, Jr. et al.
patent: 4041376 (1977-08-01), Furuto et al.
patent: 4114088 (1978-09-01), Laws
patent: 4724394 (1988-02-01), Langer et al.
Mueller Robert W.
Wieder Kenneth
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