What is IMS (Ion Mobility Spectrometry)?
Ion Mobility Spectrometry is an analytical technology to separately detect gaseous compounds in a mixture of analytes. The separation is based on the specific drift times, that ionized compounds need to pass a fixed distance (drift tube) in a defined electric field. The drift times of each substance is determined by it’s ion’s mass and geometric structure as slowing collisions with the drift gas tube are more frequent for sterically demanding structures. Therefore IMS can even differentiate between isobaric molecules. For detection, the resulting ion current is measured by an electrometer as a function of time.
IMS (ion mobility spectrometry) is an analytical technique ideal for the analysis of gaseous samples and the headspace of liquid samples.
IMS is extremely fast and sensitive and is the ideal technique when fast results are needed, when very low levels of compounds are seeked or when there is an interest in taking the analysis to the point of need rather than taking the samples to the laboratory.
IMS and 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 | MCC/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:
- Ideal for detecting variations in known matrices
- Quickly spots minor differences in complex samples
- Screens faster and more reliably than human sensory panels
- As sensitive as standard GCMS for a wide range of VOC
- Inherent two-dimensional separation allows fast throughput of complex samples
Low ongoing cost of ownership
- Simplicity of operation means the system just keeps running
- Reproducibility and repeatability mean low frequency of calibration
- Designed to run continuously in the lab or at site
- Requires only high purity nitrogen as carrier and drift gas
- Can be operated by minimally trained staff
- Uses standard laboratory consumables
- Routine maintenance-conducted by end-user
At home in the laboratory or on-site
- Compact all in one solution (sampling, separation, detection and analysis in one box)
- Easy to transport
- Simple interchange between advanced user or turn-key interface
- Ideal for remote locations
- Can store data locally for interrogation or download, or transmit via a network
- No vacuum pump to maintain
Intuitive software
- Allows simple on-instrument output of results and/or data-mining by advanced users
- Makes complex chromatogram comparison easy
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