SOLVENT EFFECTS ON SPF AND BROAD-SPECTRUM PROTECTION 159 2,6-naphthalate (Table IV and Figure 2B). The rest of the solvents only caused a minimal shift (1–2 nm) toward either the shorter or longer wavelengths. In the case of ethylhexyl salicylate, shea butter ethyl esters, diethylhexyl 2,6-naphthalate, and tris(PPG-3 benzyl ether) citrate shifted the λmax signifi cantly toward shorter wavelengths (p 0.05, Table IV and Figure 2C), the rest of the solvents did not cause a signifi cant change. The mix- tures of diethylhexyl 2,6-naphthalate and the UVB fi lters had three absorption peaks, similar to diethylhexyl 2,6-naphthalate alone. All solvents except for diisopropyl adipate caused a signifi cant shift in butyl methoxydibenzoylmethane’s λmax (p 0.05) diethyl- hexyl 2,6-naphthalate shifted the λmax toward a shorter wavelength, whereas the rest of the solvents caused a bathochromic shift. Diethylhexyl 2,6-naphthalate, butyloctyl sa- licylate, and polyester-8 caused double peaks for butyl methoxydibenzoylmethane (Table IV and Figure 2D). In the case of the UV fi lter blend, diethylhexyl 2,6-naphthalate caused a signifi cant hypsochromic shift (p 0.05) the rest of the solvents did not cause a signifi cant change in the UVB region (Table IV and Figure 2E). Isopropyl myristate, ethylhexyl methoxycrylene, and polyester-8 did not cause a signifi cant change in the UVA range, whereas the rest of the solvents shifted the λmax (p 0.05) to either a shorter wavelength (diethylhexyl 2,6-naphthalate) or longer wavelength (rest of the solvents). Table III Critical Wavelength (nm) of the UV Filter–Solvent Mixtures INCI name 1:9 Mixture with H 1:9 Mixture with EHS 1:9 Mixture with BMDM 2.3:7.7 Mixture with UV fi lter blend 1 Isododecane 324 357 - - 2 Cyclotetrasiloxane and cyclopentasiloxane 322 354 - - 3 Olea europaea (olive) fruit oil 323 326 382 378 4 C12-15 alkyl benzoate 321 325 382 378 5 Shea butter ethyl esters 322 323 381 377 6 Mineral oil 323 324 7 Helianthus annuus (sunfl ower) seed oil 324 323 - - 8 Isopropyl isostearate 322 322 - - 9 Dimethicone 322 323 - - 10 Heptyl undecylenate 323 322 381 377 11 Isopropyl myristate 322 328 380 376 12 Caprylic/capric triglyceride 322 326 381 377 13 Ethanol 331 330 - - 14 Ricinus communis (castor) oil 325 321 - - 15 Propanediol dicaprylate/caprate 323 323 381 377 16 2-Ethylhexyl palmitate 322 323 - - 17 Diethylhexyl 2,6-naphthalate 353 353 383 377 18 Pentylene glycol 327 319 - - 19 PPG-3 benzyl ether ethylhexanoate 323 324 383 378 20 Tris(PPG-3 benzyl ether) citrate 323 328 384 380 21 Butyloctyl salicylate 330 329 382 377 22 Diisopropyl adipate 322 320 381 377 23 Ethylhexyl methoxycrylene 387 386 387 386 24 Polyester-8 356 356 384 379 H: homosalate, EHS: ethylhexyl salicylate, BMDM: butyl methoxydibenzoylmethane. - refers to solvents in which BMDM was insoluble.

Table IV Wavelength of Maximum Absorbance INCI name Homosalate Ethylhexyl salicylate Butyl methoxy-dibenzoylmethane Mixture Wavelength (nm) 1 Isododecane 310 310 - - 2 Cyclotetrasiloxane and cyclopentasiloxane 309 310 - - 3 Olea europaea (olive) fruit oil 309 310 361 310, 361 4 C12-15 alkyl benzoate 310 310 361 310, 361 5 Shea butter ethyl esters 297 297 362 310, 361 6 Mineral oil 310 310 - - 7 Helianthus annuus (sunfl ower) seed oil 309 310 - - 8 Isopropyl isostearate 309 309 - - 9 Dimethicone 309 309 - - 10 Heptyl undecylenate 309 309 361 310, 361 11 Isopropyl myristate 309 309 361 310, 359 12 Caprylic/capric triglyceride 309 309 361 310, 361 13 Ethanol 309 309 - - 14 Ricinus communis (castor) oil 309 310 - - 15 Propanediol dicaprylate/caprate 309 309 361 310, 361 16 2-Ethylhexyl palmitate 309 310 - - 17 Diethylhexyl 2,6-naphthalate 297 (and 335, 351) 297 (and 335, 350) 297 (and 350) 297 (and 335, 350) 18 Pentylene glycol 309 309 - - 19 PPG-3 benzyl ether ethylhexanoate 309 309 361 310, 361 20 Tris(PPG-3 benzyl ether) citrate 309 297 362 310, 361 21 Butyloctyl salicylate 310 310 311, 362 310, 361 22 Diisopropyl adipate 309 309 358 310, 360 23 Ethylhexyl methoxycrylene 312 311 362 311, 355 24 Polyester-8 311 312 311, 361 311, 358 - refers to solvents in which BMDM was insoluble. JOURNAL OF COSMETIC SCIENCE 160