293 IN SITU ANALYSIS OF GLUCOSE IN COSMETIC FORMULATIONS
(provided by the slope of the calibration curve). In the following studies the blue channel
output was registered upon image analysis of all emulsions.
A typical standard curve obtained in emulsion A is given in Figure 1, while in emulsion B,
in Figure 2, left. The next step was to study the kinetics of the color-developing reaction, to
establish the optimum time point for picture capturing. For this reason, the kinetics were
studied for five preparations of emulsion B where glucose was present at a concentration
between 0.0%, and 5.45% w/w. Color development was at 25°C, upon addition of 642 µL
Table I
Composition and Properties of Tested Cosmetic Products (Source: Cosmetic S.A)
Cream A Cream B Shampoo A Gel A
Composition Aqua, Urea,
Paraffinum
Liquidum,
Glycerin,
Cetearyl Alcohol,
Glyceryl Stearate,
Peg-100 Stearate,
Petrolatum,
Panthenol,
Dimethicone,
Triacetin,
Phenoxyethanol,
Sorbitan
Sesquioleate,
Sorbitan Stearate,
Allantoin,
Caprylyl Glycol,
Ethylhexyl-
glycerin,
Hectorite,
Hydroxy-
ethylcellulose,
Disodium
EDTA, Bisabolol,
Farnesol
Aqua, Panthenol,
Cetearyl Alcohol,
Glycerine, Octyl
Stearate,
Cyclomethicone,
Paraffinum
Liquidum, Cetearyl,
Isononanoate,
Dicetyl Phoshate,
Ceteth-10 Phoshate,
Cetearyl Octanoate,
Isopropyl Myristate,
Allantoin, Sodium
Caproyl/Lauroyl
Lactylate, Stearic
Acid, Acrylamide/
Sodium Acrylate
Copolymer, Linallol,
Hydroxy Citronellal,
Benzyl Alcohol,
Eugenol,
Imidazolidinyl Urea,
Phenoxyethanol,
Methyl-/Ethyl-/
Propyl-/Butyl-
paraben, Perfume
Aqua, Sodium Laureth
Sulfate, Tea-Lauryl Sulfate,
Cocamidopropyl Betaine,
Disodium
Cocoamphodiacetate, Bis
(C13-15 Alkoxy) Pg
Amodimethicone, Salix Alba
(Willow) Bark Water, Peg-6
Caprylic/Capric Glycerides,
Peg-7 Glyceryl Cocoate,
Peg-120 Methyl Glucose
Dioleate, Sodium Chloride,
Perfume Phenoxyethanol,
Propylene Glycol, Citric
Acid, Polyquaternium-11,
Carbocysteine, Maris Sal (Sea
Salt), Disodium EDTA,
Methylparaben, Glycerin,
Panthenol, Propylparaben,
Pentylene Glycol, Butylene
Glycol, Coumarin, Sodium
Benzoate, Ethylparaben,
Urtica Dioica (Nettle) Leaf
Extract, Panax Ginseng
Root Extract, Faex Extract,
Santalum Album Seed Oil,
Potassium Sorbate
Alcohol Denat.,
Aqua,
Ammonium
Acryloydimethyl-
taurate/VP
Copolymer,
Glycerin, Aloe
Barbadensis Leaf
Juice powder
Oil %w/w 27.9 21.7 1.0 0.0
Individual
components,
%w/w
Surfactants: 8.0
Polymers: 0.35
Urea: 15
Surfactants: 3.1
Polymers: 1.0
Surfactants: 19.8 Polymers:
1.1
Ethanol: 62
Polymers: 0.6
Viscosity, mPa
[shear rate]
∼1,000 k
[0.3 rpm]
∼500 k [0.3 rpm] ∼3.3 k [6.0 rpm] ∼45 k [0.6 rpm]
Conductivity,
mS/cm
2.92 4.70 14.56 4.00
pH 6.82 (prod.)
7.31(mix.)
6.51 (prod.)
6.82 (mix.)
5.40 (prod.)
6.61 (mix.)
6.37 (prod.)
7.97 (mix.)
Transparency opaque opaque transparent translucent
pH (prod.): pH of the product pH (mix.): pH of the mixture (product +spiked glucose +WR).
Viscosity, transparency, oil %w/w and individual components %w/w refer to untreated cosmetic product,
while conductivity refers to the mixture (product +spiked glucose +WR). pH of both the product and the
mixture is provided.

294 JOURNAL OF COSMETIC SCIENCE
Table II
Optimization Data in Terms of Amount of WR Added/g of Cosmetic Preparation
μL WR/g emulsion R2 Linear dynamic range (%w/w glucose)
100 0.993 0.00–1.43*10−3
186 0.980 0.00–2.29*10−3
445 0.998 0.00–4.96*10−3
642 0.994 0.00–7.50*10−3
Table III
Analytical Parameters Obtained for Various Channels Upon Digital Image Analysis of Glucose Standards in
Emulsions A and B
Channel (emulsion) Linear Equation R2 Linear Dynamic Range (%w/w glucose)
Red (A) −2406x +199.5 0.962 0.00–6.37*10−3
Red (B) Poor linear dependence
Green (A) −10990x +193.8 0.987 0.00–6.37*10−3
Green (B) −8400x +180.8 0.991 0.00–7.08*10−3
Blue (A) −8976x +201.2 0.992 0.00–6.37*10−3
Blue (B) −7869x +170.9 0.994 0.00–7.50*10−3
RGB average (A) −7410x +198.0 0.992 0.00–6.37*10−3
RGB average (B) −5657x +185.9 0.990 0.00–7.08*10−3
Hue (A) 1602x +230.9 0.892 1.82–6.37*10−3
Hue (B) Poor linear dependence
Saturation (A) 11411x +16.7 0.989 0.00–6.37*10−3
Saturation (B) 5764x +44.6 0.972 0.14–7.50*10−3
Brightness (A) −2479x +200.4 0.986 0.00–8.00*10−3
Brightness (B) −1045x +209.5 0.833 0.63–7.50*10−3
R2: correlation coefficient.
Figure 1. Left: Linear relationship between blue color component intensity and glucose concentration in
emulsion A standards. Below, a picture of the corresponding wells is given, which was used to extract the
graph data (where glucose concentration is indicated (in 10−3% w/w)). Right: Saturation profile of the same
emulsion A preparations, against glucose concentration.