STABILITY OF PEDIATRIC SUNSCREEN EMULSION 377 PREPARATION OF THE TOWELETTES A coeffi cient of impregnation (C.I.) of 3 was chosen for our formulation, with a viscosity of less than 350 cps. The different permeation coeffi cients were calculated from experimental determinations using as a standard the commercial towelettes currently available on the mar- ket. The volume required to moisten each individual towelette was calculated as follows: ( VOL ml):50g m2 ×0.2m ×0.175×3ml g×1 = 5.25 ml ORGANOLEPTIC CHARACTERISTICS After macroscopic observations of the preparations, the emulsion was found to be creamy to the touch, and was easily spread but felt slightly sticky after application to the skin. On the other hand, the towelette preparation was found to be homogenously impreg- nated and easy to apply, and it left a pleasant soft feeling on the skin. These results were constant at each time and temperature interval, with no signifi cant changes in organolep- tic characteristics, texture, or appearance. After heat treatment at 40°C, there was an increase in the consistency of the emulsion, with the formation of a thin solid layer on the surface of its airtight container. However, no modifi cations were observed in the towelettes contained in the single-dose sachets. DRY MATTER The defi nition of the intervals was carried out in the laboratory for the three consecutive, identical, batches from the emulsion and towelette formulations. After each triplicate analysis per formulation, average values for the results and standard deviation were calculated, result- ing in an interval range of 24–29% for the emulsion and 3.5–4.2% for the towel. This differ- ences in interval range may be attributed to the non-woven structure of the towlette, which limits loss of moisture and therefore improves stability. The results are shown in Table III. As shown by Figures 1 and 2, the results of the dry matter analysis do not show any signifi cant variability between the emulsion and towel formulations. Moreover, this Table II Towlette Test and Emulsion at Time 0 Analysis Specifi cation Results T0 E0 Organoleptic characteristics Milky white emulsion coconut smell A A Dry matter 24.0–29% (emulsion) 3.5–4.2% (towelette) 3.9% 27.30% Density 0.985–0.995 g/m3 NA 0.988 pH 7.2–7.5 7.24 7.23 Microbiology control 100 UFC/g 1 2 Rheological characteristics 280–350cps NA 298 Stability in centrifuge Without alteration NA A Stability in oven Without alteration A A A: agreed. NA: did not agree. NA: not applicable.

JOURNAL OF COSMETIC SCIENCE 378 parameter not only remains constant, but framed within the above predefi ned interval, ranging between 25.62% and 27.11% for the emulsion and 3.75% and 3.90% for the towelette (see Figures 1 and 2). DENSITY The parameter of density determines the consistency of the emulsion and must be main- tained in a state of fl uidity in order to impregnate the towel through capillary action. The density values for an emulsion must fall within the 0.985–0.995 g/m3 range, a value that Table III Results for Dry Matter Analysis of the Emulsion and the Towlette Formulations Dry matter emulsion Dry matter towelette Batch Mean ± Standard dev. Mean ± Standard dev. 1 24.90% 0.00577 3.70% 0.06110 2 28.40% 0.02517 4.02% 0.06028 3 26.80% 0.03055 3.79% 0.09504 Figure 1. Evolution of dry matter results for the emulsion. Figure 2. Evolution of dry matter results for the towelette preparation.