Table 2.

A Summary of Breath Analysis Technologies

Analysis Method	Instrument	Sampling Method	LOD	Analysis Time	Advantages	Limitations	Suitable for POC Application
Benchtop GC[39,40]	GC-FID/TCDa; GC-MS; GCxGC-MS;	Sorbent trap SPME	pptf	Long	Most widely used; High separation capability; Compound identification available;	Bulky size; Heavy weight; Dedicated personnel needed; Sample preparation needed;	No
Selected Ion Flow Tube[30–32]	SIFT-MS	Direct input	ppbg to ppt	Real time	Rapid analysis; High sensitivity; Allow breath-by-breath analyses; No sample preparation needed;	Bulky size; Heavy weight; High cost; Dedicated personnel needed;	No
Proton Transfer Reaction [41]	PTR-MS	Direct input	ppb to ppt	Real time	Rapid analysis; High sensitivity; Allow breath-by-breath analyses; No sample preparation needed;	Bulky size; Heavy weight; High cost; Dedicated personnel needed;	No
Ion Mobility Spectrometry[33–35]	FAIMSb	Direct input	ppmh to ppb	Short	Portable; Fast; No sample preparation needed;	Low separation capability; Background VOC interference;	Yes
Electronic Nose[21, 36, 37]	AuNPsc; CNTsbd; CPse; Color-metric;	Direct input	ppm to ppb	Short	Easy to use; Highly portable; Low cost; No sample preparation needed;	Low separation capability; Sensors drift overtime; Background VOC interference;	Yes
Portable GC[42]	Portable GC; Proposed portable 2D GC;	Sorbent trap	sub-ppb	Moderate	Portable; Fully automated; High separation capability; High sensitivity; No sample preparation needed;	More complicated than 1D portable GC	Yes

^aFlame ionization detector/Thermal conductivity detector

^bField Asymmetric Ion Mobility Spectrometry

^cGold nanoparticles

^dCarbon nanotubes

^eConducting polymers

^fparts-per-trillion, 10⁻¹²

^gparts-per-billion, 10⁻⁹

^hparts-per-million, 10⁻⁶