WO2013122485A1

WO2013122485A1 - Ion mobility spectrometer

Info

Publication number: WO2013122485A1
Application number: PCT/PL2012/000109
Authority: WO
Inventors: Mirostaw MAZIEJUK; Wiesław GALLEWICZ; Michał CEREMUGA; Jarosław ŁAWREŃCZYK
Original assignee: Wojskowy Instytut Chemii I Radiometrii
Priority date: 2012-02-16
Filing date: 2012-10-18
Publication date: 2013-08-22
Also published as: PL229390B1; WO2013122485A8; PL398138A1

Abstract

The invention is characterised by greater functionality with regard to the analysis of signals coming from the gases detected, as well as being simpler and cheaper to construct. The essence of the chamber lies in the fact that it has two zones, an IMS zone (3) and a DMS zone (4). In the ionization area (5) of the IMS zone there is an ionization source (7), and in the drift area (6) of the IMS zone, in addition to the collecting electrode (9), there is a control electrode (8). The electrode is controlled by a voltage (10) changing in a fixed cycle. In the DMS zone there are control electrodes (11) and collecting electrodes (12).

Description

Ion mobility spectrometer

This invention relates to an IMS ion mobility spectrometer for gas analysis.

Ion mobility spectrometry permits the detection and identification of most organic substances regarded as being highly toxic. These are most often classical spectrometers operating at a temperature of about 50°C, with a high level of sensitivity, but not very high resolution, which in practice leads to false alarms. After detecting chemical contamination, the indicator generates a warning signal, i.e. it activates a beep and light or sends a signal to activate user-defined devices, such as ventilation devices or alarm systems. The number of false alarms should be as low as possible, as this undermines confidence in the contamination detection system and may cause the unnecessary implementation of emergency procedures.

The chamber for the IMS detector is divided into two areas. The first is the area from the semi-permeable membrane to the injection grid, in which ionization takes place from a β- or a-radioactive source. The second is the drift area - from the injection grid to the collecting electrode. Metal rings are located in this area. A high voltage (generally 1.5 kV to 3 kV) is applied to the grid in front of the radioactive source and the metal rings from the source to the collecting electrode have ever lower potentials. Thus the field is shaped so that the ions from the ionization area move in straight lines to the collecting electrode. Most gaseous substances have different mobility, so the transit time of the ions through the drift area varies, allowing for their identification.

Polish Patent Specification No. PL 187470 describes an ion mobility spectrometer chamber. In the drift area of the chamber there is a set of metal rings, generating a linear electrical field, divided by ceramic rings, fulfilling the function of insulators. European Patent Specification EP 2343546 describes an ion mobility spectrometer. In the drift area of the chamber there are metal rings, generating a linear electrical field.

The Enviromcs OY WO 2009/ 122017A1 international application describes the method of an ion mobility spectrometer for gas analysis. The method includes stages in the ionization of the gas sample, flow of the ionized gas along the extended measurement chamber, the measurement of ion mobility on the measuring electrode, the separation of ions with different mobilities on the collecting electrodes and the final measuring electrode. Ions of specified mobilities are taken up from the ionized gas sample flowing between pairs of flat electrodes, of which there are between a few and a dozen and to which is applied a high-intensity electric field high voltage with a high frequency.

The aim of the invention was to develop a chamber with enhanced functionality for the determination of gases.

This objective was achieved in the spectrometer chamber according to the invention, comprising a gas inlet and outlet, an ionization source, a control electrode, and a collecting electrode. The essence of the chamber lies in the fact that it has two zones, an IMS zone and a DMS zone. In the ionization area of the IMS zone there is an ionization source, and in the drift area of the IMS zone, in addition to the collecting electrode, there is a control electrode controlled by a voltage changing in a fixed cycle, in the DMS zone there are control electrodes and collecting electrodes.

In the chamber according to the invention, with the aid of one controlled electrode positioned in the drift area of the IMS zone, the same effect is achieved as that of using several or even a dozen pairs of collecting and measuring electrodes. Because of this, the spectrometer is simpler and cheaper to construct and much more functional in terms of the analysis of the signals from the gases detected.

The spectrometer chamber according to the invention is shown in the drawing, where Figure 1 shows a construction diagram and Figure 2 the electrode control.

The chamber with the gas inlet 1 and outlet 2 is divided into IMS zone 3 and DMS zone 4. The IMS area is divided into an ionization area 5 and a drift area 6. In the ionization area there is an ionization source 7. In the drift area there is a control electrode 8 and an IMS collecting electrode 9, connected to a control system 10. In the DMS zone there are control electrodes 1 and collecting electrodes 12. The chamber is fixed in a mounting bracket 13 and 14.

Claims

Patent Claim

A spectrometer chamber comprising a gas inlet and outlet, an ionization source, a control electrode, a collecting electrode, wherein there are two zones, an IMS zone (3) and a DMS zone (4). In the ionizing area (5) of the IMS zone there is an ionization source (7), in the drift area (6) of the IMS zone, in addition to the collecting electrode (9) , there is a control electrode (8), which is controlled by a voltage (10) , changing in a fixed cycle, and in the DMS zone there are control electrodes (11) and collecting electrodes (12).