A regulatory-first selection framework for fumed silica grades spanning FDA 21 CFR, USP/NF, EP, and REACH compliance across the SEMISIL portfolio.
A regulatory-first selection framework for fumed silica grades spanning FDA 21 CFR, USP/NF, EP, and REACH compliance across the SEMISIL portfolio.
FDA compliance for fumed silica in food applications is governed primarily by 21 CFR 172.480 (silicon dioxide as direct additive, ≤2% by weight) and 21 CFR 178.3297 (indirect food contact). Hydrophilic grades with BET surface areas of 150–300 m²/g and SiO₂ purity ≥99.8% are standard selections. SEMISIL 150 and S-200 meet these requirements without surface treatment, making them suitable as anti-caking agents in powdered foods and as flow aids in food-contact adhesives. Buyers should confirm each supplier lot ships with a current FDA compliance declaration — not just a generic statement of composition.
Pharmaceutical-grade fumed silica must conform to USP/NF monograph for Colloidal Silicon Dioxide and the European Pharmacopoeia (EP) monograph for Colloidal Anhydrous Silica. These require SiO₂ content ≥99.0% (dried basis), loss on drying ≤2.5%, loss on ignition ≤2.0%, and heavy metals below defined limits (Pb ≤10 ppm, As ≤3 ppm). SEMISIL 200 (BET 200 ±25 m²/g) is the workhorse pharma grade — used as a glidant at 0.25–1.0% in tablet formulations and as a thickener in topical gels at 2–6%. Each lot requires a Certificate of Analysis referencing the specific monograph tests.
Any fumed silica sold in the EU above 1 tonne/year requires REACH registration under EC 1907/2006. Synthetic amorphous silica (CAS 112945-52-5) is registered at the highest tonnage band (\>1000 t/a). SEMISIL hydrophilic grades carry full REACH registration with exposure scenarios covering industrial use in coatings, adhesives, sealants, and pharmaceutical manufacturing. Hydrophobic grades (HMDS- or DDS-treated) are registered under separate CAS numbers. Buyers importing into the EU should verify the supplier’s Only Representative appointment or own registration — non-compliance risks SVHC classification delays at customs.
Not every application requires pharmaceutical-grade purity. Over-specifying wastes 20–40% on material cost. Direct food additives require FDA 21 CFR 172.480 compliance — use untreated hydrophilic grades (S-150, S-200). Pharmaceutical tablet and topical formulations need USP/NF + EP dual-monograph grades with full CoA per lot. Food-contact packaging adhesives fall under 21 CFR 178.3297 — standard industrial hydrophilic grades often qualify. Industrial coatings for food-processing equipment need only REACH registration plus an FDA-compliant composition declaration. Always request the specific regulatory dossier, not a generic TDS.
The table below maps SEMISIL grades to regulatory frameworks, key purity thresholds, and primary application sectors. Use this as a first-pass screening tool — final qualification requires supplier CoA review and end-use regulatory counsel.
| Grade | BET (m²/g) | SiO₂ Purity | FDA 21 CFR | USP/NF | EP | REACH | Primary Use |
|---|---|---|---|---|---|---|---|
| S-150 | 150 ±20 | ≥99.8% | 172.480 ✓ | — | — | ✓ | Food anti-caking, flow aid |
| S-200 | 200 ±25 | ≥99.8% | 172.480 ✓ | ✓ | ✓ | ✓ | Pharma glidant, topical gel thickener |
| S-300 | 300 ±30 | ≥99.8% | 172.480 ✓ | ✓ | ✓ | ✓ | High-surface pharma, controlled release |
| S-380 | 380 ±30 | ≥99.8% | — | — | — | ✓ | Industrial thixotropy, not food/pharma |
| H-150 | 150 ±20 | ≥99.6% | — | — | — | ✓ | Hydrophobic, coatings reinforcement |
| H-200 | 200 ±25 | ≥99.6% | — | — | — | ✓ | Hydrophobic, moisture-sensitive systems |
For FDA food-contact applications, specify untreated hydrophilic grades (S-150 or S-200) with ≥99.8% SiO₂ purity and current 21 CFR 172.480 declarations. For pharmaceutical use, require USP/NF + EP dual-monograph compliance with per-lot CoA — SEMISIL 200 is the standard starting point.
Yes — synthetic amorphous silica (including fumed silica) is permitted as a direct food additive under 21 CFR 172.480 at concentrations up to 2% by weight of food. Only untreated hydrophilic grades with SiO₂ ≥99.8% qualify. Surface-treated (hydrophobic) grades are excluded from this regulation.
Pharma-grade fumed silica must meet USP/NF and EP monograph tests for heavy metals, loss on drying, and ignition residue — with per-lot Certificate of Analysis. Food-grade only requires FDA 21 CFR 172.480 compositional compliance. Pharma grades cost 20–40% more due to tighter QC and documentation requirements.
Generally no. Hydrophobic grades are surface-treated with HMDS or DDS, altering the CAS number and excluding them from 21 CFR 172.480. They may qualify for indirect food contact (21 CFR 178.3297) in packaging adhesives, but direct food use requires untreated hydrophilic grades.
BET 200 m²/g is the standard for glidant use at 0.25–1.0% loading in direct compression tablets. Higher BET (300 m²/g) increases flow improvement but can affect dissolution profiles. Lower BET (150 m²/g) provides less glidant efficiency and is more common in food applications.
Yes — any fumed silica sold into the EU above 1 tonne/year must be REACH-registered under EC 1907/2006. Synthetic amorphous silica (CAS 112945-52-5) is registered at the \>1000 t/a band. Buyers should verify the supplier holds registration or has appointed an Only Representative.
Request the specific regulatory dossier, not just a Technical Data Sheet. For pharma grades, require a per-lot Certificate of Analysis referencing USP/NF or EP test methods. For FDA compliance, ask for a current 21 CFR 172.480 declaration letter. For REACH, request the registration number and tonnage band confirmation.
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