Table 2.

Tested sample preparation protocols for TEM analysis of the E171 materials.

Protocol	P1	P2	P3	P4	P5	P6
Weighed mass	25 mg	88 mg	88 mg	88 mg	88 mg	88 mg
Concentration	2.5 mg/mL	2.5 mg/mL	2.5 mg/mL	2.5 mg/mL	2.5 mg/mL	2.5 mg/mL
pH	10	6–7	6–7	6–7	6–7	6–7
Probe sonication	35 kJ	-	-	10 kJ	10 kJ	10 kJ
Centrifugation	-	30’	2 h	-	30’	2 h