# US 9,753,012 B2 · Method and device for the identification of gases

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- Number: US 9,753,012 B2
- Document ID: US9753012B2
- Status: Granted
- Kind: B2
- Application number: 15/186,239
- Filed: 2016-06-17
- Published: 2016-12-22
- Granted: 2017-09-05
- Earliest claimed: 2015-06-19
- Assignees: Airsense Analytics GmbH
- Applicants: Airsense Analytics GmbH
- Inventors: Andreas Walte; Wolf Muenchmeyer; Bert Ungethuem
- Web page: https://patentgrep.com/patent/US9753012B2

## CPC

- G01N 27/622: Ion mobility spectrometry
- H01J 49/0027: {Methods for using particle spectrometers}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

Method and device for identifying gases and/or ion mobility spectrometer and method for offsetting residual humidity are provided. The object of the invention is to develop a generic method for offsetting residual humidity in an ion mobility spectrometer and a related device, which has a simple structure and which fully exploits the reduced diffusion. This is achieved by a variable drift chamber drift gas velocity, which leads to differing penetration depths of the humidity into the drift chamber, and thus to variable residual humidities in the drift chamber. Methods of this type and the associated devices for detecting and identifying gases are used to recognise and identify chemical compounds, in particular explosive materials or material compounds and/or those which are damaging to health, and which must be identified in very low concentrations.

## Claims

### Claim 1

A method for identifying gases, the method comprising:
forming product ions by ionizing the gases to be identified;
measuring drift times of the product ions through a drift chamber (5); and
evaluating the measured drift times of the product ions,
wherein the measuring the drift times of the product ions comprises:
accelerating the product ions through an electrical field to drift velocities in the drift chamber (5), and
guiding a drift gas into the drift chamber (5) counter to a direction of movement of the product ions, wherein:
a drift gas velocity (13) of the drift gas is varied in the drift chamber (5); and
at the same time that the drift gas velocity (13) is varied in the drift chamber (5), an overall drift gas flow is varied to maintain constancy of a drift gas velocity (12) in a reaction chamber (4).

### Claim 2 (depends on 1)

The method according to claim 1, characterized in that by modifying the drift gas velocity (13) in the drift chamber (5), a constant average residual humidity is set in the drift chamber (5).

### Claim 3 (depends on 1)

The method according to claim 1, characterized in that water vapor and/or a dopant gas in the air is used as a drift gas.

### Claim 4 (depends on 3)

The method according to claim 3, characterized in that ammoniac or acetone is used as a dopant gas.

### Claim 5

A device for identifying gases consisting of an inlet system (1), at least one ion source (2), at least one reaction chamber (4) and one drift chamber (5), which are separated by an ion inlet device (3), at least one screen grid (8) and one detector (7) and ion guidance electrodes (6), and a drift gas circuit characterized in that in the drift gas circuit, a variable restriction (20) is switched,
so that a drift gas velocity (13) in the drift chamber (5) and/or a drift gas velocity (12) in the reaction chamber (4) can be modified;
wherein a mobility of a product ion Cl−[H2O]n in the drift chamber (5) is used for determining an unknown residual humidity in the drift chamber (5).

### Claim 6 (depends on 5)

The device according to claim 5, characterized in that the variable restriction (20) is a proportional valve.

### Claim 7 (depends on 5)

The device according to claim 5, characterized in that the variable restriction (20) is a pump.