## 2 Results and Discussion
### Discriminative Value of the D-HS-MultiSPME/Tenax Method for Individual Human Milk Samples
1: acetic acid (LRI: 1460), 2: methanooic acid (LRI: 1534), 3: propanoic acid (LRI:1547), 4: butanoic acid (LRI: 1637), 5: pentanoic acid (LRI: 1746), 6: hexanoic acid (LRI: 1862), 7: heptanoic acid (LRI: 1968), 8: octanoic acid (LRI: 2076), 9: nonanoic acid (LRI: 2172), 10: decanoic acid (LRI: 2378), 11: 2-methyl-1-propanol (LRI: 1077), 12: 1-butanol (LRI: 1140), 13: (_E_)-1-penten-3-ol (LRI: 1145), 14: 3-methyl-1-butanol (LRI: 1205), 15: 1-pentanol (LRI: 1250), 16: 1-octen-3-ol (LRI: 1445), 17: 2-ethyl-1-hexanol (LRI: 1488), 18: pentanal (LRI: 980), 19: hexanal (LRI: 1088), 20: heptanal (LRI: 1190), 21: (_E_)-2-hexneal (LRI: 1233), 22: octanal (LRI: 1295), 23: (_E_)-2-heptrenal (LRI: 1346), 24: nonanal (LRI: 1409), 25: (_E_)-2-octencal (LRI: 1445), 26: (_E_,_)-2-4-heptrolateral (LRI: 1484), 27: decanal (LRI: 1498), 28: (_E_,_)-2-4-heptrolateral (LRI: 1521), 29: (_E_)-2-nonencal (LRI: 1563), 30: benzaldehyde (LRI: 1563), 31: 2-propanone (LRI: 793), 32: 2-butanone (LRI: 904), 33: 2,3-butanedione (LRI: 975), 34: 3-octanone (LRI: 1264), 35: 6-methyl-5-hepten-2-one (LRI: 1351), 36: 2-nonanone (LRI: 1397), 37: 3-octan-2-one (LRI: 1423), 38: 2-undecanone (LRI: 1611), 39: acetophenone (LRI: 1702), 40: ethyl acetate (LRI: 878), 41: methyl decanoate (LRI: 1601), 42: \(\alpha\)-pinene (LRI: 1023), 43: camphene (LRI: 1071), 44: \(\beta\)-pinene (LRI: 114), 45: 3-caren (LRI: 1156), 46: \(\beta\)-myrcene (LRI: 1163), 47: dl-limonene (LRI: 1210), 48: 1,8-cineole (LRI: 1220), 49: \(\gamma\)-terpinene (LRI: 1259), 50: \(\alpha\)-terpinolence (LRI: 1295), 51: (_E_)-geranylacetone (LRI: 1885), 52: pyrazine (LRI 1226), 53: 2-methylpyrrole (LRI: 1575), 54: 2-pentylfurane (LRI 1236), 55: furural (LRI: 1486), 56: 5-methyl-2-furfurral (LRI: 1601), 57: toluene (LRI: 1041), 58: styrene (LRI: 1275), 59: Butynolactone (LRI: 1685), 60: phenol (LRI: 2049). this combinatorial method. Indeed, numerous aldehydes (\(n=13\)), carboxylic acids (10), terpenes (10), ketones (9), alcohols (7), and esters (2) were identified. In addition, several minor compounds in human milk, such as furans, lactones, pyrazine and pyrrole compounds, are also recovered and identified through this D-HS-MultiSPME/Tenax method. Moreover, to the best of our knowledge, nine compounds are unanticipated in human milk. Among them, methanoic and propanoic acids, 2-methyl-1-propanol, 3-methyl-1-butanol and \(\gamma\)-butyrolactone belonged to chemical families generally linked to lipid oxidation in milk [25]. \(\beta\)-phellandrene is also detected for the first time in the milk of at least one of the mothers. As a terpene, this compound may derive from a maternal diet [19] or cosmetic usage. Similarly, pyrazine and 2-methylpyrrole are first found in one mother's milk. Although these chemicals were largely reported in roasted food products [8], their origin in human milk is not clear. Finally, phenol is also reported in this study. Phenols were already detected in HS-SPME extracts of human milk [20; 21], but even if they may derive from forage in bovine milk [54], their origin in human milk remains unexplained. Hence, the compounds identified in the present study correspond to approximately 30% of the total volatile compounds currently found in human milk [11]. This proportion must be considered in the light of the objective that was mainly centered on volatile and semi-volatile compounds (LRI < 2600). Therefore, heavy compounds like steroids or some pollutants, which are largely reported in studies focusing on specific compounds related to environmental contamination or medication, will not be detected by this method [11; 62; 63]. Given the high variation in milk volatile profile between women [27] and the restricted number of individual human milk samples analyzed here, the number of compounds identified in human milk is expected to be further increased with the analysis of additional individual milk samples using this innovative D-HS-MultiSPME/Tenax method.