Table 2 Summary of factors reported to influence volatile organic compounds within exhaled breath
Study | Environmental considerations | Patient-related factors | Breath collection methods | Method of analysis | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Ambient air | Specific room for breath sampling | Detection contamination | Physiological conditions | Setting | Sampling period | Sample collection and extraction methods | Breath portion | Volume | Route | Flow rate | Stability of VOCs | Analysis platform | Sensitivity | Repeatability | VOC identification | |
Peled, N. [20] | NR | NR | NR | NR | the University of Colorado Cancer Center and Denver Veterans Affairs Medical Center, America | NR | Mylar bag + SPME | all | 750 mL | mouth | NR | NR | GC-MS | NR | NR | NR |
Bousamra, M., 2nd [21] | collected. | NR | NR | NR | NR | NR | Teldar bag | all | 1Â L | NR | NR | NR | FT-ICR-MS | NR | NR | NR |
Fu, X. A. [22] | collected. | NR | NR | NR | NR | before resection | 1Â L Tedlar bag | all | 1Â L | NR | NR | NR | FT-ICR-MS | NR | NR | confirmed by FT-ICR-MS/MS |
Li, M. X. [61] | collected. | clinic room | Tedlars bags and syringes were tested free of contamination. | no diet controls | the James Graham Brown Cancer Center at the University of Louisville, America | NR | 1Â L Tedlar bag | all | NR | NR | 5 mL/min | NR | FT-ICR-MS | NR | NR | NR |
Schumer, E. M. [23] | NR | NR | NR | NR | NR | NR | Tedlar bag | all | 1Â L | NR | NR | NR | FT-ICR-MS | NR | NR | NR |
Phillips, M. [27] | NR | NR | NR | NR | NR | NR | a dual-bedded sorbent trap + TD | all | 1 L | mouth | NR | at least 3 years | GC-MS | NR | replicate assays at two independent laboratories | according to mass spectrometry library NIST |
Shaohua Xie [49] | collected. | a ventilated room | NR | Sit over 10 min, avoid food and smoke for at least 8 h. No deep inhalation before sampling, no ventilation through nasal and no second breaths during sampling. | Sichuan Cancer Hospital, China | before biopsy or resection | 500 mL Tedlar bag + Bio-VOC breath sampler + SPME | last portion | 450mL | mouth | NR | 1 week | GC-MS | 35–200 m/z | NR | according to mass spectrometry library NIST 08 |
Pengqiang Liao [28] | NR | NR | NR | Participants were required not to eat for 8 h before breath collection, and rest for at least 10 min in a well-ventilated room; Deep breathing before sampling and nasal ventilation and secondary breathing during sampling were not allowed. | Sichuan Cancer Hospital; Nanchong Central Hospital; Longquanyi CDC | before resection | 500 ml Tedlar bag + SPME | last portion | 450mL | mouth | NR | within 7 days | GC-MS | 35-200amu | NR | according to mass spectrometry library NIST and RI |
Chen, X. [24] | collected. | a specific controlled room | NR | Avoid high fat food any antioxidant supplements for at least 24 h. Fasting for 12 h, then stayed in a specific room. Next day before the breakfast, the participants arrived in a specific controlled room for breath sample collection.The participants didn’t brush teeth, and gargled with plain tap water 15 min before. | Sir Run Run Shaw Hospital, China | NR | TD | last portion | 1 L | mouth | NR | NR | GC-MS | 45–500 m/z | Repetitive tests were performed on collected air and breath samples. | according to mass spectrometry library NIST 05 and NIST 05 s |
Rai, S. N. [58] | collected. | a clinic exam room | NR | NR | healthy control: patient family members the James Graham Brown Cancer Center and Jewish Hospital at the University of Louisville | NR | 1Â L Tedlar bag | all | 1Â L | mouth | 5 mL/min | NR | FT-ICR-MS | NR | NR | NR |
Ding, X. [60] | collected. | a fixed room | NR | Participants fasted for at least 6 h. Participants were asked not to ingest spicy food, alcohol, or coffee the night before exhaled breath collection. Participants first gargled with pure water | PKUPH Cohort: the Department of Thoracic Surgery, Peking University People’s Hospital; CHPKU Cohort: the Cancer Hospital of Peking University | before PET-CT scanning and the morning before surgery | Tedlar bag | all | NR | mouth | NR | within 4 h | HPPI-TOFMS | m/z < 500 | NR | detected by HPPI-TOFMS |