Table 1.

Primary particle size, charge and specific surface area of E171 and E153

	DLS Mean (nm)	Particle size (TEM) Mean (nm)	Surface area (BET) m2/g	Zeta potential mV
E171	19 (1%)	135 ± 46 (27)	7.9	−37.2 ± 2.0
	880 ± 390 (94%)	305 ± 61 (12)
	3200 (5%)	900 ± 247 (5)
E153	283 ± 60	50 ± 10 (12)	1935	− 24.7 ± 1.6
		950 ± 200 (20)

Dry particle size was measured by TEM analysis. Three size groups were observed from E171 and two size groups from E153. Surface area was determined by BET analysis. Zeta potential was determined by PALS. The data on TEM, surface area, and zeta potential are expressed as the mean ± SD (number of particles is indicated in the brackets). The hydrodynamic size distribution was also measured by DLS. Three size distributions were observed for E171. Numbers in brackets indicate the intensity distribution