information Value of Sultaines - HARKE Group

Surfactants
Viscosity (cps)
120,000
100,000
80,000
60,000
40,000
20,000
0
0.0 0.5 1.0 1.5 2.0 2.5
NaCl (%)
Hydroxysultaines
SLES-1/CMEA
systems
CAPB-FA
LAPB-FA
LAPHS-FA
CAPHS-FA
CAPHS-T
CAPB-T
Betaines
SLES-2
systems
CAPB-FA
LAPB-FA
CAPHS-FA
LAPHS-FA
CAPHS-T
CAPB-T
CAPHS-FA LAPHS-FA CAPHS-T CAPB-FA LAPB-FA CAPB-T
The procedure uses a water-soluble, yellow tetrazolium
salt (MTT {3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium
bromide}), which is reduced by succinate
dehydrogenase in the mitochondria of viable cells to a
purple, insoluble formazan derivative. Substances which
damage this mitochondrial enzyme inhibit the reduction
of the tetrazolium salt. The amount of MTT reduced by a
culture is therefore proportional to the number of viable
cells.
As per MatTek’s protocol, the samples are diluted to a
20% solution and the appropriate tissue preparation is
made. 100 microlitres of the test article and distilled
water (negative control) were added to the micelles
containing the EpiOcular samples. The six-well plates
containing the dosed EpiOcular samples were then
incubated at 37°C, 5% CO 2 and >90% humidity. The
results were then converted from an ET-50 value into a
familiar estimated Draize score.
According to this test, the ingredient is considered
more or less irritating depending on the Draize Score: 0-
15 means non-irritating, minimal, 15.1-25 is mild, 25.1-
50 is moderate and 50.1-110 is considered severely
irritating or extreme. Traditionally, true amphoterics or
highly ethoxylated nonionics are used to reduce or
minimise eye irritation of alkyl ethoxylated sulfates and
alkyl sulfates. Previous studies show that betaines have
minimal impact on this property. 2
EpiOcular comparisons were made for two anionic
combinations, one with SLES-2 and one with sodium
coco-sulfate to determine if sultaines displayed similar
Figure 4 - Viscosity
responses of sultaines &
betaines
References
1. McIntyre Group, McIntyre
Chemistry Manual 1997, 46-60
2. T. Schoenberg, Formulating
with Betaine and Amphoteric
Surfactants 1997, 2.
3. F. Wagner, D. Colovic, J.
Kiplinger, G. Cosby & E. Leroy, A
Novel Look at Amphoteric
Surfactants, Poster, 2010.
Contact
Denis Bendejacq
Rhodia CTRA
Labo Home & Personal
Care
52, rue de la Haie Coq
F-93308 Aubervilliers
France
E-mail: denis.bendejacq@
eu.rhodia.com
Website: www.rhodia.com
behaviour to betaines. The results (Table 1) show that,
although all surfactants tested individually at 10-15%
active were severely irritating, the combination of an
anionic with either a betaine or sultaine starts to mitigate
the irritation potential.
Sultaines especially reduced the irritation when
incorporating more sultaine than anionic in the SLES-
2/amphoteric combinations. For example 11.25% CAPHS
and 4.75% SLES-2 had a score of 6.6, non-irritating and
the corresponding CAPB was 22.4, or mild. The score of
this SLES-2/CAPHS combination was even lower than the
benchmark baby shampoo that claims ‘no more tears’.
Similarly, the estimated Draize scores of sodium cocosulfate
were reduced when incorporating a betaine or
sultaine. The impact of the ethoxylation of the alkyl
sulfate in combination with a sultaine was more dramatic
than the sulfate/betaine combinations, as also indicated in
the foam studies.
Conclusion
Sultaines molecular design makes them an ideal
amphoteric choice for personal care formulations where
mildness and foam are important. They are free of
processing aids and preservatives and are able to reduce
the irritation of common anionics more efficiently than
betaines.
Sultaines are highly compatible with anionic surfactants
and enhance foaming properties of ethoxylate-free
surfactants such as sodium coco-sulfate and also sulfatefree
surfactants such as disodium lauryl sulfosuccinate. In
every combination of anionic/amphoteric, sultaines
delivered superior or equal foam when compared to
betaines at the 90% confidence level.
Chain length of the betaine or sultaine and anionic
selection is more important in boosting foam than pH
effect. The degree of ethoxylation on an alkyl sulfate in
combination with a triglyceride-based CAPHS has a
favourable impact on mildness and foam. Sultaines build
viscosity similarly to their betaine counterpart and can
easily substitute them into a personal care formulation
while simultaneously boosting foam and mildness.
* - The authors would like to thank Dusanka Colovic Vos of
Rhodia, University Park, for her assistance in running many of the
foam and viscosity tests, Jon Kiplinger and Tom Ruch of Rhodia
CRTA for their assistance with EpiOcular correspondence and
interpretation of results and Eric Leroy of CRTA for his guidance
on relating the results to molecular structure as originally
published in a poster format. 3 They would especially like to thank
Denis Bendejacq of CRTA for all of his assistance and guidance in
writing this article.
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28 Speciality Chemicals Magazine January 2012 www.specchemonline.com