Table 2. Summary of Analytical Techniques Used for Differentiating Branched and Linear Isomers.
| column | column dimensions | analytical reagents | injection volume | instrument | PFAS isomers (with count) studieda | study |
|---|---|---|---|---|---|---|
| FluoroSep-RP Octyl column | 150 × 2.1 mm, 3 μm particle size | methanol and water (3 mM formic acid in water, adjusted to pH 4.0 with ammonia) | 10 μL | LC-MS/MS | PFOA (4), PFOS (6), PFOSA (2) | Chen et al. 201510 |
| FluoroSep RP Octyl column | 150 × 2.1 mm, 3 μm particle size | methanol and water (adjusted to pH 4.0 with ammonium formate) | 20 μL | HPLC–MS/MS | N-EtFOSA(12), FOSA (6), PFHpA (4), PFHxA (8), PFOA (10), PFOS (11), PFNA (11), PFDA (3), PFUnA (7), PFDoA (18) | Benskin et al. 200776 |
| BEH C18 column | 2.1 × 50 mm, 1.7 μm particle size | methanol and 2 mM ammonium acetate | 1 μL | UPLC MS-MS | PFOS (2) | Gu et al. 201616 |
| Hypersil Gold precolumn + Betasil C18 column | 10 × 2.1 mm, 5 μm particle size + 50 × 2.1 mm, 5 μm particle size respectively | methanol and water (both with 10 mM aqueous ammonium acetate | 10 μL | HPLC | PFHxS (2), PFOS (2) | Belkouteb et al. 2020,13 Ahrens et al. 201677 |
| Zorbax Extend-C18 column | 2.1 × 50 mm, 1.8 μm particle size | methanol and ammonium acetate in water (pH 6) | 10 μL | HPLC + Q-TOF | PFOS (8) | Trojanowicz et al. 201978 |
| Zorbax RRHD Eclipse Plus C18 column | 100 mm × 2.1 mm, 1.8 μm particle size | methanol and 5 mM ammonium acetate in water | LC-MS/MS | PFOS (2) | Park et al. 202019 | |
| Zorbax Eclipse Plus C18 column | 4.6 mm × 100 mm, 3.5 μm particle size | 3% methanol in water and 10 mM ammonium acetate in methanol | HPLC + MS/MS | PFPeA, PFHxA, PFHpA, PFOA, PFNA, PFBS, PFPeS, PFHxS, PFHpS PFOS, FPeSA, FHxSA, FOSA, N-TAmP, FHxSA (2 for each) | Rodowa et al. 2020,20 Barzen-Hanson et al. 201779 | |
| C18, analytical column | 100 × 3.0 mm, 5 μm particle size | methanol and 20 mM ammonium acetate in water | 1 mL | QTOF | PFOS, PFHpS, PFHxS, PFOA, and PFHpA (2 for each) | Tenorio et al. 202070 |
| Perfluorinated phenyl (PFP) phase + X-Terra C18 phase | 150 × 2.1 mm, 5 μm particle size 100 Å pore size + 100 × 3.0 mm, 3.5 μm particle size, 125 Å pore size respectively | methanol and 4 mM ammonium acetate in water | ion trap mass spectrometer (LCQ | PFOS (7) | Langlois et al. 200680 | |
| Thermo Acclaim 120 C18 column + FluoroSep RP Octyl column (3 mm, 2.1 mm150 mm | 4.6 × 150 mm, 5 μm particle size + 2.1 × 150 mm, 3 μm particle size | acetonitrile and 10 mM ammonium acetate in water | HPLC + MS/MS | PFHxS (2), PFOS (6), PFOA (6) | Gao et al. 201923 |
a
Note: 2 indicates br (grouped together/single isomer studied) and L-PFAS.