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Ion Mobility Spectroscopy (IMS) Instruments Maintenance Management, Support, and Repair

Category Chemical/Explosives
Type Analytical
Ease of Use 5 out of 5
Determination Capability 2 out of 5

How it works

IMS uses an ionization source like Nickel 63, a weak radioactive metal, to put a positive or negative charge on a chemical. Once the chemical is a charged particle, it can be moved by placing a similar charge near it to push it or an opposite charge to attract it.

In the case of IMS, the ionized particle is introduced into a drift tube and the opposite charge is electronically introduced on the other end of the tube at the detector. Due to attraction, the particle moves down the drift tube to the opposite end. Using temperature and drift gas, the particle will move through the tube at a very reproducible rate. The amount of time it takes to reach the end of the tube is called the drift time. This time can be compared to previously recorded drift times of chemicals of concern. If the time of the particle is within the established drift time window, the software reports the particle as the chemical of concern.

IMS can detect multiple chemicals because the particle size is directly comparable to the amount of time it takes to “drift” to the end of the tube. The larger the particle, the longer it takes to make it to the other end for detection. Separation and drift time comparison makes this instrument a simple and powerful tool to determine the presence or absence of a chemical agent like Sarin even when potential interfering chemicals are present.

IMS is one of the most frequently used technologies for determining Chemical Agents. It is simple and can distinguish which chemical is present. Like all techniques, it is important to understand the limitations of IMS. The biggest problem is that compounds with similar molecular weights take similar times to drift. As a result wintergreen oil (molecular weight = 152) will be incorrectly identified as mustard gas (molecular weight = 158).


IMS a very good tool for initial determination of the presence or absence of Chemical Agents, however any positive hits should be confirmed by a second technique.

KD Analytical supports IMS Instruments

KD Analytical offers a suite of services for IMS instruments (as well many other analytical instruments) that can save you money and time and help you to guarantee the readiness of your equipment and team.

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