Table 2.
Size determination of nine TiO2 materials, from which two are reference materials, NM103 and NM104, and seven are pigments provided by commercial suppliers
| TiO2 material | Rt in aF4 (min) | aF4-UV (Øh) (nm) | aF4-MALS (Øg) (nm) | Øg/Øh ratio | spICPMS (nm) | SEM aggregate size bin (modal) (nm) | Primary particle (nm) |
|---|---|---|---|---|---|---|---|
| NM103 | 9.8 | 209 | 190 | 0.91 | 122 | 100–160 (155) | 13–35 |
| NM104 | 10.6 | 224 | 240 | 1.07 | 120 | 100–160 (135) | 13–35 |
| Pigment-1 | 15.7 | 333 | 420 | 1.26 | 128 | 160–250 (200) | 60–300 |
| Pigment-2 | 16.2 | 343 | 370 | 1.08 | 159 | 250–400 (320) | 60–300 |
| Pigment-3 | 16.7 | 354 | 370 | 1.05 | 221 | 250–400 (320) | 60–300 |
| Pigment-4 | 17.0 | 360 | 310 | 0.86 | 156 | 250–400 (320) | 60–300 |
| Pigment-5 | 17.4 | 368 | 400 | 1.09 | 220 | 250–400 (345) | 60–300 |
| Pigment-6 | 19.5 | 414 | 390 | 0.94 | 156 | 250–400 (375) | 60–300 |
| Pigment-7 | 22.7 | 480 | 440 | 0.92 | 158 | 400–650 (415) | 60–300 |
Size determinations by asymmetric flow field flow fractionation (aF4) separation and UV254 nm detection were performed on the basis of retention time after calibration with polystyrene standards. spICPMS single particle ICPMS, SEM scanning electron microscopy, Øg gyral diameter in nm from aF4-MALS detection using the Berry model for data processing, Øh hydrodynamic diameter in nm. SEM results are given as size bins in which modal diameters are observed and as size range (smallest-largest) in diameters of the constituting primary particles. Between brackets the modal diameters, estimated from a fit of SEM data points