J. Cosmet. Sci., 56, 153–166 (May/June 2005)
Detection thresholds of capsaicin: A new test
to assess facial skin neurosensitivity
ROLAND JOURDAIN, PHILIPPE BASTIEN, OLIVIER DE LACHARRIE` RE,
and GILLES RUBINSTENN, L’Ore´al Recherche, 90 Rue
du Ge´ne´ral Roguet, 92583 Clichy (R.J., O.d.L.,
G.R.), and L’Ore´al Recherche, 1 Avenue Euge`ne
Schueller, 93601 Aulnay sous Bois (P.B.), France.
Accepted for publication February 15, 2005.
The goal of this study was to assess the accuracy/reliability
of a new test designed to measure cutaneous neurosensitivity.
The test was carried out on a random population of 150 healthy
adult women and was based on the determination of individual
detection thresholds of topically applied capsaicin. Five capsaicin
concentrations were used in 10% ethanol aqueous solution (3.16
× 10-5%; 1 × 10-4%; 3.16 × 10-4%; 1 ×
10-3%; 3.16 × 10-3%). The methodology used to attain the
detection threshold was capsaicin application in increasing
concentration on the nasolabial folds. The vehicle was simultaneously
applied following a split-face, single-blind plan. The test
was stopped as soon as the subject reported a specific sensation
lasting more than 30 seconds on the capsaicin side. The safety
of the test was judged as excellent by the panelists since all
the reported sensations were considered as slightly or moderately
perceptible. The test allowed the classification of the test
population according to six threshold levels corresponding to
the sensitive reaction to one of the five capsaicin concentrations
and to the absence of sensitivity to the highest concentration.
Surprisingly, the distribution of the population was not unimodal
and seemed to reveal the existence of two different sub-groups:
individuals with a low capsaicin detection threshold and those
with a high threshold. These two sub-populations strongly differed
in their respective self-perception of sensitive skin. The higher
the self-declared sensitive skin incidence was, the lower the
detection threshold was. This new test of skin neurosensitivity
is easy, quick, and truly painless. It appears to be a promising
tool for the cosmetic diagnosis of sensitive skin.
J. Cosmet. Sci., 56, 167–174 (May/June 2005)
Use of triphenyltetrazolium chloride in preservative
D. S. ORTH and K. S. ECK, Neutrogena Corporation, 5760 West
96th Street, Los Angeles, CA 90045.
Accepted for publication March 1, 2005.
Preservative efficacy testing without counting colonies was
done by determining growth in dilutions of inoculated product
following enrichment in Letheen broth with 0.001% triphenyltetrazolium
chloride (TTC) in 96-well microtiter plates. Bacterial growth
was indicated by the development of a red/pink color in the
enrichment broth. The method was used to determine log reductions
of bacteria at specified times after inoculation, and D-values
were calculated using the reciprocal of the highest dilution
showing growth (pink color) as the log CFU/ml bacteria at each
time point. The method using TTC was validated by demonstrating
that D-values for Staphylococcus aureus, Pseudomonas aeruginosa,
Burkholderia cepacia, and Escherichia coli in 44 aqueous cosmetic
and OTC-drug products were virtually identical to those obtained
when using Alamar Blue_ in the miniaturized system (1). Plotting
D-values obtained using TTC as a function of D-values obtained
using Alamar Blue gave a line with a slope of 0.98, which shows
excellent agreement of results obtained by the two methods.
This miniaturized assay system has been used for more than three
years for preservative efficacy testing of several hundred cosmetic
and OTC-drug product samples in our laboratory. It is recommended
for laboratories that conduct large numbers of preservative
J. Cosmet. Sci., 56, 175–182 (May/June 2005)
Study of sensory properties of emollients used
in cosmetics and their correlation with physicochemical properties
MARI´A EMMA PARENTE, ADRIANA GA´ MBARO, and GERARDO
SOLANA, Ca´tedra de Quý´mica Cosme´tica
(M.E.P., G.S.) and Seccio´n Evaluacio´n Sensorial,
Ca´tedra de Ciencia y Tecnologý´a de Alimentos
(A.G.), Facultad de Quý´mica, Universidad de la
Repu´blica, Montevideo, Uruguay.
Accepted for publication February 28, 2005.
Eight liquid emollients (mineral oil, sunflower oil, squalane,
decyl oleate, isopropyl myristate, octyldodecanol, dimethicone,
and cyclomethicone) were characterized by instrumental and sensory
methods and evaluated to determine the relationship between
sensory and instrumental measures. Sensory analysis was carried
out by a panel of 14 assessors, who evaluated the following
attributes: difficulty of spreading, gloss, residue, stickiness,
slipperiness, softness, and oiliness. The physicochemical properties
measured were spreadability (at one-half minute and at one minute),
viscosity, and superficial tension. Data collected were statistically
analyzed by analysis of variance (ANOVA), principal component
analysis (PCA), and linear partial least squares regression
analysis (PLS). In consideration of their physicochemical characteristics,
the studied emollients were sorted into three groups, in which
the silicones distinctly separate from the rest. Sensory characteristics
enabled the discrimination of four groups of emollients where,
besides the two silicones, isopropyl myristate was also differentiated.
PLS revealed that emollient sensory attributes could be well
predicted by instrumental measurements.
J. Cosmet. Sci., 56, 183–192 (May/June 2005)
Simultaneous determination of chlorinated bacteriostats
in cosmetic and pharmaceutical products
LAI-HAO WANG, MEY TSO, and CHUN-YU CHIN, Department of Applied
Chemistry, Chia Nan University of Pharmacy and Science, Tainan,
Taiwan, 71743, R.O.C.
Accepted for publication April 4, 2005.
A high-performance liquid chromatography method has been developed
for simultaneous determination of triclosan (2,4,4_-trichloro-2_-hydroxydiphenyl
ether) and triclocarban (3,4,4_-trichlorocarbanilide) in cosmetic
and pharmaceutical products. The two compounds could be separated
on a Nucleosil C18 column and eluted with acetonitrile and water
(70:30, v/v) as the mobile phase and detected with a differential
refractive index detector. The retention times of triclosan
and triclocarban were 5.81 and 2.99 min, respectively. The results
obtained were in good agreement with those obtained by a differential
pulse voltammetric method.
J. Cosmet. Sci., 56, 193–204 (May/June 2005)
Spatial and angular distribution of light incident
on coatings using Mie-scattering Monte Carlo simulations
MASAKO YAMADA, MATTHEW D. BUTTS, and KAREN K. KALLA, General
Electric Global Research Center, 1 Research Circle, Niskayuna,
NY 12309 (M.Y., M.D.B.), and Procter and Gamble, 11810 East
Miami River Road, Cincinnati, Ohio 45252 (K.K.K.).
Accepted for publication March 14, 2005.
We show the results of Mie-scattering Monte Carlo models developed
to simulate the optical properties of light incident on particle-containing
coatings. The model accommodates mixtures of particles with
different sizes and complex refractive indices, enabling the
simulation of formulations, including pigments. The simulation
tracks trajectories of photons as they propagate through the
turbid medium, calculating both angular and spatial light intensity
distributions. Scalar quantities such as total transmission
and reflection, and haze and diffuse reflectance, are also calculated.
J. Cosmet. Sci., 56, 205–206 (May/June 2005)
Journal of the Society of Cosmetic Chemists Japan Vol. 39,
No. 1, 2005*
J. Cosmet. Sci., 56, 207–210 (May/June 2005)
International Journal of Cosmetic Science Vol. 27, No. 1, 2005*
J. Cosmet. Sci., 56, 211–212 (May/June 2005)
IFSCC Magazine Vol. 8, No. 1, 2005*