Every sunscreen label hides the same engineering question: which UV filters, at what load, in which combination? Organic (chemical) filters are the answer for most of the world's SPF products because they dissolve cleanly, feel light and leave no white cast. But they are not interchangeable — each covers a different slice of the solar spectrum, and some actively destabilize their neighbors. Here is how the nine most-traded organic filters really behave.
First, the spectrum
UVB (290–320 nm) drives SPF and immediate erythema; UVA-II (320–340 nm) contributes pigmentation and complements SPF; UVA-I (340–400 nm) is the deep-penetration band behind photoaging and the PA+ rating. A modern "broad spectrum" claim needs real absorption across all three, and no single organic filter does it all — except one.
The UVB workhorses
Ethylhexyl methoxycinnamate (OMC, octinoxate) (CAS 83834-59-7) is the most widely used UVB filter in the world — strong absorption at 310 nm, oil-soluble, cost-efficient, limited to 10% in the EU and 7.5% under the US OTC monograph. Its weakness is photostability: it loses a meaningful share of its absorbance after a few hours of irradiation and, importantly, it accelerates the photodegradation of avobenzone (more on that below).
Ethylhexyl triazone (EHT) (CAS 88122-99-0) is the high-efficiency alternative. It has one of the highest extinction coefficients of any approved UVB filter, is intrinsically photostable, and unlike OMC it stabilizes avobenzone. It is oil-soluble with modest solubility (~15% in common esters), so it needs a good solvent oil; EU limit 5%.
Ethylhexyl salicylate (octisalate) (CAS 118-60-5) is a weaker UVB absorber on its own, but formulators love it for two things: excellent safety record (US limit 5%, EU 5%) and genuine avobenzone-stabilizing ability. It is a classic "team player" — low irritation potential in high-SPF systems.
Phenylbenzimidazole sulfonic acid (PBSA, ensulizole) (CAS 27503-81-7) is the rare water-soluble filter (as its sodium salt). That makes it the go-to for light lotions, gels and "no-oil-feel" daily products where it delivers a clean, dry finish. It covers UVB up to ~340 nm, so it quietly contributes to UVA-II as well; EU limit 4% (as acid), US limit 4%.
Padimate O (ethylhexyl dimethyl PABA) (CAS 21245-02-3) is the legacy filter of the group — an efficient UVB absorber still found in some markets, but it has been phased out of the EU and is absent from most new global launches. We list it for completeness and reformulation support.
The UVA specialists
Avobenzone (butyl methoxydibenzoylmethane) (CAS 70356-09-1) is the only globally accepted UVA-I filter of the dibenzoylmethane class and the backbone of most broad-spectrum products sold in the US (limit 3% in the US, 5% in the EU). Its famous problem: it photodegrades within hours, losing over half its absorbance unless it is photostabilized. Every avobenzone formula is really a stabilization exercise.
Terephthalylidene dicamphor sulfonic acid (Mexoryl SX) (CAS 92761-26-7) is a photostable, water-soluble UVA filter covering 290–400 nm with a λmax near 345 nm. It pairs beautifully with PBSA in "watery-feel" daily products and with oil-soluble filters in beach products; EU limit 10%.
Diethylhexyl butamido triazone (Uvasorb HEB) (CAS 154702-15-5) is an oil-soluble photostable UVA-II/UVB filter of the triazine family — strong at 330–340 nm, excellent solubility in ester oils, EU limit 3%. A quiet workhorse for high-SPF Asian and EU formulations.
The all-rounder
Bis-ethylhexyloxyphenol methoxyphenyl triazine (Tinosorb S, BEMT) (CAS 187393-00-6) is arguably the best-performing organic filter on the market: broad absorption from UVB deep into UVA-I (λmax 310 and 343 nm), essentially photostable, oil-dispersible, high molecular weight that resists skin penetration, EU limit 10%. If a formula has room for only one premium filter, it is this one. In the US it is still awaiting FDA approval, which is why American formulators lean on avobenzone instead.
Photostability: the rule that decides combinations
- Never pair avobenzone with OMC alone. The cinnamate transfers energy to the dibenzoylmethane and both degrade faster — the classic reason "SPF 50 drops to SPF 20 by lunchtime".
- Stabilize avobenzone with octisalate, EHT, BEMT or octocrylene; or avoid the problem entirely by building the UVA side on Mexoryl SX, Uvasorb HEB and Tinosorb S.
- Water-soluble pair: PBSA + Mexoryl SX gives a light, low-oil daily lotion with credible UVA protection.
- Classic high-SPF skeleton: OMC (cost/efficiency) + EHT (photostable UVB boost) + avobenzone + octisalate (stabilizer), or OMC + BEMT + Uvasorb HEB for an avobenzone-free claim.
- Asia-market finish: replace part of the oil load with esters like caprylic/capric triglyceride to dissolve crystalline filters (EHT, BEMT) and keep the texture light.
Side-by-side comparison
| Filter | CAS No. | Main band | Solubility | EU max | US OTC max | Role |
|---|---|---|---|---|---|---|
| OMC | 83834-59-7 | UVB | Oil | 10% | 7.5% | Workhorse UVB |
| Ethylhexyl triazone | 88122-99-0 | UVB | Oil | 5% | — | High-efficiency, photostable |
| Octisalate | 118-60-5 | UVB | Oil | 5% | 5% | Booster / stabilizer |
| PBSA | 27503-81-7 | UVB + UVA-II | Water (salt) | 4% | 4% | Light daily textures |
| Padimate O | 21245-02-3 | UVB | Oil | not permitted | 8% | Legacy / reformulation |
| Avobenzone | 70356-09-1 | UVA-I | Oil | 5% | 3% | Global UVA-I standard |
| Mexoryl SX | 92761-26-7 | UVA | Water | 10% | — | Photostable water-soluble UVA |
| Uvasorb HEB | 154702-15-5 | UVA-II + UVB | Oil | 3% | — | Photostable triazine UVA |
| Tinosorb S | 187393-00-6 | Broad spectrum | Oil/dispersion | 10% | — | Premium broad-spectrum |
Specs to check when sourcing
- Assay / purity — HPLC ≥ 97–98% for premium grades; lower assay means you are paying for impurities that contribute color and odor.
- Color and clarity — white to off-white powders (avobenzone, EHT, BEMT) or pale yellow liquids (OMC, octisalate); darkening signals oxidation of the filter itself.
- Individual transmittance curves — ask for the UV spectrum on the COA; it is the only proof the λmax matches the label claim.
- Residual solvents and heavy metals — critical for EU (REACH) and pediatric claims.
- For crystalline filters (EHT, BEMT, avobenzone) — confirm particle size and recrystallization behavior in your oil phase; poor solvent choice shows up weeks later as grit.
Shanghai Better Chemical supplies the full organic UV filter portfolio above — OMC, ethylhexyl triazone, octisalate, PBSA, avobenzone, Mexoryl SX, Uvasorb HEB and Tinosorb S — China origin, cosmetic grade, with TDS/COA/MSDS on request. Contact our team for combination advice matched to your target market.