Table 2.
Comparison analytical methods.
| Method | Description | Real-time analysis | Cost | Risk of contamination | Sample preparation | Online/offline | Storage time |
|---|---|---|---|---|---|---|---|
| Gas chromatography-mass spectrometry (GC–MS) | Separation of chemical components based on their relative affinity with a capillary column. Components elute from the GC-column with different retention times after which they are captured, ionised, accelerated, deflected and detected by the MC. | – | + | + | + | Offline | + |
| Ion mobility spectrometry (IMS) | Separation of chemical components on the basis of differences in ion mobilities within an electric field | + | – | – | – | Online | – |
| Selective ion flow tube-mass spectrometry (SIFT-MS) | Absolute quantification of trace VOC by ionisation with precursor/reagent ions | + | + | – | – | Online | – |
| Electronic nose (E-nose) | Array of sensors creating a smell “fingerprint” with pattern recognition modules resembling the olfactory system | – | – | + | + | Offline | + |
| Field asymmetric ion mobility spectrometry (FAIMS) | Separation of chemical components on the basis of differences in ion mobilities within an electric field | + | – | – | – | Online | – |
++: =applicable/high/long; -: =not applicable/low/short; Online: =immediate analysis of the sample; Offline: =preconcentration of samples and possibility of storing samples for later analysis.