perspectives from research Submitted on behalf of TDMA & TC E172 - - PowerPoint PPT Presentation

Report on E171 (titanium dioxide) and E172 (iron oxide) - analytical perspectives from research

Submitted on behalf of TDMA & TC E172

1./2. April 2019 Parma

Report on E171 (titanium dioxide) and E172 (iron oxide) - analytical perspectives from research

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Five E171 grades were analysed by SEM, BET, Brookhaven XDC and CPS DC 25 E172 grades were analysed by SEM, TEM, BET, Brookhaven XDC and LD Yellow 3 Red 2 Red 11 Black 1 Sample B Sample A Sample C Sample D Sample E

Product Name Colour Crystal Phase Yellow 3 Yellow Goethite FeO(OH) Red 2 Red Hematite Fe2O3 Red 11 Red Hematite Fe2O3 Black 1 Black Magnetite Fe3O4 Sample Anatase (%) A 99,9 B 99,7 C 99,6 D 99,1 E 99,4

SEM results E171 E171 is not a nano product

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• SD low for E171 Manufacturer (M1, M2, M3)
• Inexperienced laboratories could find very different results

A B C D E M-1 SEM 0.137 0.105 0.115 0.163 0.106 M-2 SEM 0.140 0.101 0.110 0.173 0.102 M-3 SEM 0.138 0.108 0.113 0.162 0.105 0.000 0.050 0.100 0.150 0.200 0.250

median x50 (µm)

A B C D E M-1 SEM 18 46 36 10 44 M-2 SEM 18 50 37 10 47 M-3 SEM 19 41 36 14 44 10 20 30 40 50 60

Q0<100nm (%)

A B C D E LAB A SEM 4 5 3 22 LAB A STEM 12 12 19 7 42 LAB B TEM 29 55 41 15 59 10 20 30 40 50 60

Q0<100nm (%)

A B C D E LAB A SEM 0.179 0.162 0.165 0.222 0.142 LAB A STEM 0.145 0.145 0.126 0.183 0.12 LAB B TEM 0.127 0.095 0.109 0.164 0.095 0.000 0.050 0.100 0.150 0.200 0.250

median x50 (µm)

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Correlation x50 with dminVSSA high TEM vs BET

0% 20% 40% 60% 80% 100% 100 200 300 400 500 600 700 800

Yellow 1

Frequency Cumulative %

0% 20% 40% 60% 80% 100% 20 40 60 80 100

Red 11

Frequency Cumulative % 0% 20% 40% 60% 80% 100% 50 100 150 200 250 300

Red 2

Frequency Cumulative %

• VENATOR is the sole manufacturer
• f E172
• Primary particle size analysis

possible for red and yellow but not for black Iron Oxides

• Rubout of crystals in a monolayer on

the surface is important for accurate results

• Will be difficult to find an external lab

which is able to measure Iron Oxides

• High correlation with dminVSSA

y = 0.945x - 0.0049 R² = 0.9975 y = 1.0082x + 0.0047 R² = 0.9865 0.01 0.1 1 0.010 0.100 1.000

x50 (µm) dminVSSA (µm)

x50 feret.min vs dminVSSA x50 ECD vs dminVSSA Linear (x50 feret.min vs dminVSSA) Linear (x50 ECD vs dminVSSA)

Particle Size for Risk Assessment?

 We support the EFSA approach to analyse the particle size of food additives as pristine material, in the food matrix and in biological media  However, the guidance document is not consistent on page 21 in the evaluation of agglomeration or aggregation state by two independent methods  Standard EM can only measure the constituent particles size and not the agglomeration or aggregation state  The second method must corelate with EM to be a suitable screening method and the sample must be dispersed to a plateau  Nevertheless, for many products (Black Iron Oxides) EM doesn’t work and alternatives must be possible  The Nano Define decision-flow scheme for dispersion criteria on page 79 should be adjusted by the dispersion technique and mandatory correlation with EM

Constituent Particles

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Mobile Particle Size for Risk Assessment

 “Once a material is classified as nano according the constituent particle size of the EU definition, the information on the mobile particle size under realistic conditions (food matrix, biological media, etc.) is needed.  Dispersability has been reported as a founding base for the grouping of the nano materials” (EChA, “Appendix R.6-1 for nano materials applicable to the Guidance on QSARs and Grouping)  The OECD TG318 for aqua toxicity could be a good base for food application, a defined dispersion energy according to NIST 1200 is recommended and indicates the particle size in aqueous media  The same issues apply for food, what is the right dispersion energy, what is the dispersion medium, degradation, dissolution…….  An initial approach for the determination of the E171 and E172 smallest mobile particle size of the pristine material or in the food matrix is presented on the next slides

Defined Dispersion Energy

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Volume weighted Particle Size Standardised dispersion energy

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Particle size control of E171 and E172 by a standardised dispersion procedure:

• Comparing production dispersion

energy density with laboratory scale using NIST 1200 TG

• The energy density of 240 J/ml is

three times higher than normally applied in production wet milling of TiO2

• Full redispersion of agglomerates

without breaking up aggregates or constituent particles

• M. Stintz propose 270 J/ml for

synthetic amorphous silica (SAS), Powder Technology 318 (2017) 451- 458 and Nanomaterials 8 (2018) 454

Aggregate size is determined by the production process (page 17 line 14) Not possible to disperse completely to unbounded constituent particles Dispersion with low energy

Dispersion Energy

0.261 0.253 0.328 3.373 0.100 1.000 10.000

Yellow1 Red2 Red11 Black1 Volume X50 (µm)

E172

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Volume based particle sizes for risk assessment Comparison E171/ E172

0.280 0.264 0.267 0.369 0.304 0.100 1.000 10.000

A B C D E Volume X50 (µm)

E171

0.8 1.1 0.8 0.1 1.3 0.100 1.000 10.000

A B C D E Volume Nano (%)

E171

• “Dispersibility has been reported as a founding base for the grouping of the nano

materials” (EChA, “Appendix R.6-1 for nano materials applicable to the Guidance on QSARs and Grouping)

Brookhaven XDC Dispersion Energy 240 J/ml

5 2 1 0.100 1.000 10.000

Yellow1 Red2 Red11 Black1 Volume Nano (%)

E172

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Conclusion on Particle Size Analysis E171/ E172

 E171 is not a nano material according the EU definition  E172-Black Iron Oxides are not nano products  The dispersion criteria of the Nano-Define decision-flow scheme shall be corrected for “constituent particles”  Realistic volume based particle sizes for toxicological testing can be achieved by dispersion energies <300 J/ml  Using the NIST 1200 TG volume based particle sizes of different products can be easily compared by different laboratories  Implementation of a dispersibility criterium in the risk assessment  CPS DC and Brookhaven XDC are suitable instruments to measure mobile nano particles

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Back Up

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Absolute particle size depends on the method

E172 Particle Size by Brookhaven XDC & LD

• Dispersion Energy 240 J/ml
• Same trend for both methods

0.236 0.319 0.261 0.145 0.253 0.527 0.192 0.220 0.234 0.253 0.425 0.493 0.623 0.328 0.640 0.747 0.690 0.500 0.610 0.870 0.580 0.570 0.590 0.600 0.690 0.717 0.900 0.770 0.000 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800 0.900 1.000 Yellow1 Yellow2 Yellow3 Red1 Red2 Red3 Red4 Red5 Red6 Red7 Red8 Red9 Red10 Red11 Geothite Hematite

[µm]

Average XDC X50 Volume (µm) Average MS2000 X50 Volume (µm)

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Good sensitivity for high nano contents

E172 Nano Content by XDC & LD

• Brookhaven XDC is more sensitive to fine particles than LD

5.0 3.0 5.0 12.0 2.0 1.0 6.0 5.7 5.0 1.7 1.0 1.0 1.0 1.0 1.2 0.1 0.7 8.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 4 6 8 10 12 14 Yellow1 Yellow2 Yellow3 Red1 Red2 Red3 Red4 Red5 Red6 Red7 Red8 Red9 Red10 Red11 Geothite Hematite

[%]

Average XDC Q3 (%) <100nm Averagen MS2000 Q3 (%) <100nm

Long Dispersion experiment No complete dispersion of aggregates after 3h

13 Anatase 1h Horn Sonication Anatase 2h Horn Sonication Anatase 3h Horn Sonication Some Crystal Debris More Crystal Debris Increased Crystal Debris

Anatase 3h probe sonication increased tip debris aggregates still survived Anatase 2h probe sonication more tip debris Anatase 1h probe sonication some tip debris

3600 J/ml 7200 J/ml 10800 J/ml

E171 Long Dispersion experiment Particle size analysed by CPS DC

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0.15 0.14 0.14 0.13 0.13 0.13 0.13 0.13 0.12 0.13 23.2 22.9 28.3 28.5 27.2 30.1 28.9 28.4 31.9 30.2 0.29 0.28 0.27 0.26 0.24 0.24 0.24 0.23 0.23 0.23 1.31 1.57 1.98 2.26 2.59 2.82 2.88 3.02 3.48 3.28 0.01 0.1 1 10 100 120 300 600 900 1800 3600 5400 7200 9000 10800 2 5 10 15 30 60 90 120 150 180 Dispersion Energy (J/ml) ) Dispersion Time (min) Number Median x50 (µm) Q0.<0,1µm (%) Volume Median x50 (µm) Q3<0,1µm (%)

E171/E171 food P25 nano OECD TG318 SCCS UV-Filter

SEM number feret.min: Median x50 = 0,100 µm Q0<100nm = 47% SEM number ECD: Median x50 = 0,120 µm Q0<100nm = 33%

E171 Brookhaven XDC & CPS DC results High agreement between different manufacturer

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A B C D E M 1 XDC 0.5 0.8 0.3 0.0 1.0 M 2 CPS DC 0.9 1.3 1.1 0.2 1.5 M 1 CPS DC 1.1 1.2 1.0 0.2 1.5 0.0 0.5 1.0 1.5 2.0

Q0<100nm (%)

A B C D E M 1 XDC 0.281 0.260 0.264 0.360 0.301 M 2 CPS DC 0.276 0.264 0.268 0.363 0.310 M 1 CPS DC 0.283 0.269 0.270 0.383 0.301 0.000 0.100 0.200 0.300 0.400

x50 Volume (µm)

A, 0.280 B, 0.264 C, 0.267 D, 0.369 E, 0.304

0.000 0.100 0.200 0.300 0.400 x50 Volume (µm)

A, 0.8 B, 1.1 C, 0.8 D, 0.1 E, 1.3

0.0 0.5 1.0 1.5 2.0 Q3 Volume <100nm (%)

• Small interlaboratory SD on volume particle sizes and nano contents
• High reproducibility of results

Screening of particle sizes and nano contents VSSA E172

77.0 74.3 71.9 91.0 59.8 22.1 76.4 69.2 65.4 61.6 34.2 33.3 21.0 47.5 46.8 72.6 39.0 49.3 43.6 49.6 29.8 27.3 29.4 26.9 42.9 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 Yellow1 Yellow2 Yellow3 Red1 Red2 Red3 Red4 Red5 Red6 Red7 Red8 Red9 Red10 Red11 Brown1 Brown2 Brown3 Black1 Black2 Black3 Black4 Black5 Black6 Black7 Black8 Yellow Red Brown Black

VSSA (m2/cm3)

Cubes&Spheres = 60 m2/cm3 Needles = 40 m2/cm3 Needles & Spheres = 50 m2/cm3

VSSA cut off = 60 𝑛2

𝑑𝑛3 ∗ 𝐸 3

Smallest dimension D= 3 spheres, 2 needles, 1 flakes

dminVSSA (D*) =

2𝐸 𝑊𝑇𝑇𝐵

BET

According to DIN ISO 9277, samples are heated up to 180°C in 30 min and left at this temperature for one hour before determination of the SSA under Nitrogen at 5 different pressure ratios: 0,1 – 0,15 – 0,2 – 0,25 – 0,3. The Volume Specific Surface Area (VSSA) is calculated by multiplication of the SSA with the gravity () VSSA = SSA x  Equation 1 The Monodisperse Diameter of the Volume Specific Surface Area (dminVSSA) is calculated for different particle shapes by the following equation dminVSSA (D*) =

2𝐸 𝑊𝑇𝑇𝐵

Equation 2 The VSSA cut off is calculated by the equation below. VSSA cut off = 60

𝑛2 𝑑𝑛3 ∗ 𝐸 3

Equation 3

*Smallest dimension D= 3 spheres, 2 needles, 1 flakes

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Disc Centrifuge and Dispersion

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Company Instrument Detector Disc Speed Formulation M-2 CPS DC UV-Light 405nm 18000 rpm 0,1g E171, 100 ml water, 0,06 g Calgon N M-1 Brookhaven XDC X-Ray 3000 rpm 2g E171 in 50 ml water, 0,02 g calgon N M-1 CPS DC UV-Light 470nm 18000 rpm 0,1g E171, 38 ml water, 12g PDO*, 0,05 g Calgon N Company Sonic Probe Tip Diameter Tip Length Eglible volume Nominal Power M-2 Sonoplus 2200 13 mm 250 mm 25-500 ml 750 W M-1 Sonics VCX750 13 mm 136 mm 25-500 ml 750 W

Dispersion Equipment Instrumentation, parameters and formulation

NIST 1200 Technichal Guideline Power Calibration

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