Technology

Ion Mobility Spectrometry

What is Ion Mobility Spectrometry (IMS)?

Ion Mobility Spectrometry (IMS) is an analytical technology that separates analyte mixtures into their component compounds and then detects what these compounds are.

Separation of compounds is based on the specific drift times that ionised compounds need to pass a fixed distance (drift tube) in a defined electric field. The drift time of each substance is determined by the mass and geometric structure of its own ions. These parameters determine the number and rate of collisions with the drift tube walls that, in turn, impact upon the speed of transit through the drift tube. An electrometer then measures the resulting ion current as a function of time.

IMS is an ideal tool to analyse gaseous and liquid headspace samples. Its ultra-sensitivity and rapidity make it ideal for situations where quick results are required, when compound levels are low or where analysis is better done on-site rather than in a laboratory.

Comparative specifications: IMS vs other techniques

Would you like to understand whether IMS is the right choice for your lab or application? This table may help you:

TD/GC/MSD PTR-TOF-MS SIFT-MS GC/IMS
Deployment Laboratory Laboratory Laboratory Lab & Point-of-Care
Mass range 1050 amu 20 – 180 amu < 300 Da < 1000 Da
Ions positive positive positive positive, negative
Detection limit ppbv-ppmv pptv ppbv pptv-ppmv
Gas consumption Helium Helium Helium Air
Vacuum pump needed yes yes yes no
Measurement time 60 – 120 min 30 min 30 min 10 min
Weight 96 kg 170 kg 212 kg 18 kg
Dimensions (cm x cm x cm) 88 x 56 x 50 56 x 130 x 78 90 x 72 x 88 45 x 35 x 28
Personnel needed for operation Scientist Scientist Scientist Technician

GC-IMS vs GC-MS

While IMS can be complimentary with many analytical techniques, it can often be seen as an alternative to GC-MS. So, how do they compare?

Performance
Low ongoing cost of ownership
At home, in the laboratory or on-site
Intuitive software