Table 2.
Key physical, chemical, and biological properties of the linear perfluorinated carboxylic acids from 2 to 8 carbons
| Property | Trifluoroacetic acid | Perfluoropropanonic acid | Perfluorobutanoic acid | Perfluoropentanoic acid | Perfluorohexanoic acid | Perfluoroheptanoic acid | Perfluorooctanoic acid |
|---|---|---|---|---|---|---|---|
| Abbreviation | TFA | PFPrA | PFBA | PFPeA | PFHxA | PFHpA | PFOA |
| CAS# | 76-05-1 | 422-64-0 | 375-22-4 | 2706-90-3 | 307-24-4 | 375-85-9 | 335-67-1 |
| Molecular formula | CF3COOH | CF3CF2COOH | CF3(CF2)2-COOH | CF3(CF2)3-COOH | CF3(CF2)4-COOH | CF3(CF2)5-COOH | CF3(CF2)6-COOH |
| Number of carbon atoms | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Log KOW | 0.5 | 1.5a | 2.43a | 3.262a | 3.48 | 5.024 a | 5.905a |
| Henry’s Law Constant (atm m−3 mol−1) | 1.11 × 10–7 | 4.43 × 10–6 a | 0.0051 a | 0.029a | 0.174a | 1.521a | 3.044a |
| Koc (L kg−1) | 0.17–20 | 12.7 a | 58 a | 270 a | 1247 a | 5761 | 30,440 |
| NOEC most sensitive aquatic plant (ng L−1) | 2.5 × 106b | 1.44 × 107c | 6.21 × 108c | > 1.00 × 109c | NA | > 1.02 × 109c | 5.80 × 103c |
| NOEC most sensitive aquatic animal (ng L−1) | LC50 = 7 × 107d | LC50 = 8.0 × 107d | LC50 = 1.1 × 108 d | LC50 = 1.3 × 108 d | LC50 = 1.4 × 108 d | LC50 > 1.02 × 106d | LC50 = 1.5 × 108 |
| Half-life in humans f | 16 h | NA | 72–81 h | NA | 14–49 de | 1.2–1.5 year | 2.1–10 year |