Table 3.

Potential electronic-nose applications for human and animal disease diagnoses via detection of volatile biomarker indicator compounds.

Disease/Disorder/Infection	Aroma sample source	Associated volatile biomarkers†	References
Aerobic gram negative bacteria	Intraperitoneal fluid	Terpenes, ketones	[10]
Alcoholic fatty liver disease (AFDL)	Human breath	Acetaldehyde, isoprene, 3 other unidentified VOCs	[240]
Alcohol-induced hepatic injury	Human breath	Ethane, pentane (volatile alkanes)	[241]
Allograft rejection	Human breath	Carbonyl sulfide	[242]
Anaerobic bacterial infections	Intraperitoneal fluid	Acetic acid, butyric acid	[243]
	Urine	Isobutylamine, acetic acid, butyric acid	[106,244,245]
Asthma	Human breath	Pentane, ethane, 8-isoprostane, nitric oxide, leukotriene B4, prostaglandin E2	[246–253]
Bacteremia	Blood cultures	Specific complex mixture of VOCs	[254]
	White blood cell cultures	Acetaldehyde, hexanaldehyde	[255]
Bacterial infections (local)	Human pus	Isobutyric, isovaleric, & isocaproic acids	[256]
Bacterial vaginosis	Vaginal swabs	Specific complex mixture of VOCs	[257]
Bacteriuria	Urine	Specific complex mixture of VOCs	[258]
Breast cancer	Human breath	C4-C20 alkanes, monomethylated alkanes	[67]
Cardiopulmonary disease	Alveolar air	Ethanol, acetone	[259]
Cholera	Feces	p-menth-1-en-8-ol, dimethyl disulphide	[260]
Chronic hepatitis	Alveolar air	Methyl-mercaptan, dimethyl sulfide	[261]
Chronic obstructive pulmonary disease (COPD)	Human breath	NO, H2O2, aldehydes, 8-isoprostane, nitrotyrosine, Leukotriene B4, cytokines	[99,100,262–265]
Cystic fibrosis	Human breath	Leukotriene B4, interleukin-6, carbonyl sulfide, alkanes	[192,266]
Cystinuria	Human breath	Cadaverine, piperidine, putrescine, pyrrolidine	[42,267]
Diabetes mellitus	Human breath	Acetone, ethanol, methyl nitrate, complex VOCs	[226,268]
Eye infections	Cultures of ocular fluids	Specific complex mixture of VOCs	[176]
Foetor hepaticus	Human breath	Specific complex mixture of VOCs	[269]
Haematuria	Urine	Specific complex mixture of VOCs	[270]
Halitosis	Human breath	Hydrogen sulfide, methyl mercaptan, dimethyl sulfide	[271]
Hepatic cirrhosis	Alveolar breath	Dimethyl sulfide, hydrogen sulfide, mercaptans, volatile fatty acids	[272]
	Alveolar air	Dimethyl sulfide, acetone, 2-pentanone and 2-butanone	[273]
	chronic hepatitis	Methyl-mercaptan, dimethyl sulfide	[261,239]
Hepatic coma	Alveolar air	Methyl-mercaptan, dimethyl sulfide	[261,239,274]
Hepatic encephalopathy	Blood plasma, spinal fluid	3-methylbutanal	[72]
Histidinemia	Human breath	2-imidazolepyruvic acid, 2-imidazolelactic acid, 2-imidazoleacetic acid	[42]
Hyperglycemia	Human breath	Methyl nitrate, xylene, ethylbenzene	[183,268]
Inflammatory bowel disease (IBD)	Human breath	Pentane, ethane, propane	[73,275–277]
Isochemic heart disease, angina	Human breath	Alkanes, methylated alkanes	[278,279]
Ketosis	Alveolar air	Acetone	[76]
Leg ulcers & wound healing	Contact dressings	Specific complex mixture of VOCs	[280,281]
Liver cancer	Blood	Hexanal, 1-octen-3-ol, octane	[282]
Lung cancer	Human breath	Alkanes, monomethylated alkanes	[64,278]
	Human breath	Alkanes, aromatic compounds	[283]
	Human breath	Specific complex mixture of VOCs	[234,284–286]
Maple syrup urine disease	Human breath	2-oxoisocaproic acid	[42]
Metabolic disorders	Urine	Isovaleric acid	[287]
Necrotizing enterocolitis (NEC)	Feces	2-Ethyl-1-hexanol, fewer esters present in VOCs	[288]
Oxidative stress	Human breath	8-isoprostane	[247]
Phenylketonuria	Human breath	Phenylpyruvic acid, phenyllactic acid, phenylacetic acid	[42]
Renal dysfunction and failure	Urine	Specific complex mixture of VOCs	[270]
Respiratory infections	Human breath	Specific complex mixture of VOCs	[289]
Rheumatoid arthritis	Alveolar air	Pentane	[290]
Tyrosinemia	Human breath	p-hydroxyphenylpyruvic acid	[42]
Schizophrenia	Alveolar air	Pentane, carbon disulfide, ethane	[34,35,291]
Sweaty feet syndrome	Urine, sweat, human breath	Butyric acid, hexanoic acid; trans-3-methyl-2 hexenoic acid	[37]
Urinary tract infection	Urine	Isovaleric acid, alkanes	[245]
	Urine	Specific complex mixture of VOCs	[245,292]

^†Bio-indicator compounds are volatile organic compounds (VOCs) that usually were initially identified and confirmed using gas chromatography-mass spectroscopy (GC-MS) or similar analytical equipment prior to development of corresponding e-nose reference libraries for detection.