Table 2. Physico-chemical parameters of the test materials.
| Pigment | Size in nm (d50) (TEM) | Surface in m2/g (BET) | Composition (elements in %) (oxidation, XRD, XRF) | Surface chemistry (elements in %) (XPS) | Reactivity (in μUFRAS/m2h) (FRAS) | Dissolution in water (ICP-MS, UV/Vis) | Dispersibility in DMEM-FCS (d50) (AUC-XLA) | Charge in mV (zeta potential) | Hydrophobicity (contact Angle) | |
|---|---|---|---|---|---|---|---|---|---|---|
| Mixed chlorinated DPP isomers | 39 | 62 | C 60.5, H 2.9, N 7.8, O 9.1, Cl 19.6; amorphous and crystalline; no contaminations >0.1% | C 74.8, O 8.1, N 8.3, Cl 8.9 | <1 ppm | 988 nm, AAN: 25 | N/A a | Hydrophobic (138°) | ||
| Fine Pigment Red 254 | 43 | 94 | C 60.9, H 2.8, N 7.8, O 9.0, Cl 19.9; no contaminations >0.1% Si, Br <0.1% | C 77.1, O 10.9, N 5.9, Cl 6.1 | Non-active (0.0006) | ≪1 ppm | 774 nm, AAN: 18 | −16 | Hydrophobic (135°) | |
| Coarse Pigment Red 254 | 233 | 16 | C 60.5, H 2.8, N 7.8, O 8.9, Cl 19.7; no contaminations >0.1% Si, Br <0.1% | C 79.4, O 10.0, N 5.1, Cl 5.2, | Non-active (0.0007) | <1 ppm | 352 nm, AAN: 1.5 | -41 | Hydrophobic (136°) | |
| Coarse meta-chloro DPP | 0.3–3 μm × 70–200 nm | 42 | C 60.4, H 2.9, N 7.8, O 9.1, Cl 19.8; no contaminations >0.1% | C 73.1, O 8.4, N 9.5, Cl 9, | Intermediate (0.0196) | ≪1 ppm | ≫1 μm, AAN > 10 | −11 | Hydrophobic (110°) | |
| Fine meta-chloro DPP | 30–400 nm × 10-50 nm | 64 | C 60.6, H 2.9, N 7.9, O 9.0, Cl 19.6; no contaminations >0.1% | C 73.6, O: 8.8, N 8.7, Cl 8.8 | Intermediate (0.0256) | ≪1 ppm | ≫1 μm, AAN > 33 | −12 | Hydrophobic (141°) | |
| Fine Pigment Red 101 | 15–130 nm× 4–21 nm | 107 | Fe2O3, hematite | O 54.2, Fe 27.2, C 15.7, P 1.6, Ca 0.9, S 0.2, F 0.1, Mg 0.1 | Intermediate (0.0372) | <1 ppm | >1 μm, AAN > 1000 | −27 | Hydrophilic (0°) | |
| Coarse Pigment Red 101 | 48–90 nm | 12 | predominantly Fe2O3, hematite; possibly also Fe3O4 magnetite | O 49.6, Fe 24.6, C 23.9, Na 1.9 | Intermediate (0.0200) | <1 ppm | >1 μm, AAN > 20 | −55 | Hydrophilic (0°) |
TEM: transmission electron microscopy; BET: Brunauer–Emmet–Teller; XRD: X-ray diffraction; XRF: X-ray fluorescence; XPS: X-ray photoelectron spectroscopy; FRAS: ferric reducing ability of serum; ICP-MS: inductively coupled plasma mass spectrometry; AUC-XLA: analytical ultracentrifuge; AAN: average agglomeration number.
a
Charge of mixed chlorinated DPP isomers is not detectable by the used measurement technique.