analiz cosmetic

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J. Soc. Cosinefir Chemists 19 213-223 (1968) lo68 Socuty o Cosmetic hemistt f Great Britain

Estimation of hexachlorophanecosmetic roducts

in

A REPORT BY THE METHODS OF ANALYSISSUBCOMMITTEE OF THE SOCIETY OF

COSMETIC CHEMISTS OF GREAT BRITAIN

Syn0psisMethods for analysing hexachlorophane n toiletries and cosmetics are reviewed,and discussed. reliminary experiments with uv absorption methods ndicated that the differ-ential absorption method was preferable to the one measuring absorption at fixed wave-

lengths, which could suffer interference from extraneous and irrelevant absorption.Interlaboratory collaborative tests have been carried out on certain toilet preparations,

viz. alcoholic solutions, talcs and soaps, containing hexachlorophane at levels between 0.2and 2 o, using he differential absorption method of Elvidge and Peutrell. Results show hat

the method is sufficiently accurate and specific or the determination of hexachlorophane nthese preparations.

INTRODUCTION

Hexachlorophane s used n a large number of cosmetic nd toiletryproducts. t functions as a germicide, bactericide or deodorant n productssuch as talcs, soaps, deodorant and/or antiperspirant preparations, ooth-pastes, etc., and is generally used at a concentration between 0.01% and2.0%.

The Methods of Analysis Subcommittee of the Society of CosmeticChemists of Great Britain has reviewed existing methods or estimatinghexachlorophane o find a simple specific method suitable for estimatingthis material in toilet preparations.

REVIEW OF POSSIBLE METHODS

Published methods can be grouped as follows:(1) Titration methods.

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(2) Colorimetric methods.(3) Measurement f absorption t specific wavelengths.(4) Differential absorption measurements.(5) Gas chromatography.(6) Determination of organic chlorine.

Titration methods

Potentiometric itration (1) is suitable for the pure material but notfor hexachlorophane n a product. High frequency itration techniques 2)have been used or various phenols ut they require special quipment.

Colorimetric methods

Several colorimetric methods have been used.

t Amino antipyrine-potassium erricyanideThis method s widely used and was first published by Gottlieb and

Marsh (3). Mohler and Jacob 4) considered t to be the most sensitive ndaccurate method available, whereas Larson (5) and Lord, McAdam and

Jones (6) reported that results were unreliable. The sensitivity of thereaction s pH dependent nd he result s not specific or hexachlorophane.Achmeteli (7) overcame he interference rom methyl salicylate n

toothpaste y using methylene lue instead of potassium erricyanide, utanionic detergents lso eact with methylene lue and must irst be removed.

2.6 Dibromoquinone hloroimideThis method, often known as the Gibbs method (8), is based on the

formation of a dibromo-indophenol ye which can be estimated colori-metrically. t has been adapted by Singer and Stern (9) for the determina-tion of bisphenols uch as hexachlorophane, ut is not specific.

NitrosophenolGibbs 10) examined he reaction of phenols with nitrous acid and the

[ormation of coloured nitroso compounds. troughton 11) developedmethod or the preparation f nitroso compounds ith nitric and sulphuricacids t 100C, nd their rearrangement n the presence f excess lcoholicammonium hydroxide to produce a highly coloured quinonoid adical.Lykken, Treseder and Zahn (12) modified his method and used sodiumnitrite in acetic acid to form the nitrosophenol t room emperature.


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ESTIMATION OF HEXACHLOROPHANE IN COSMETIC PRODUCTS 215

Ferric chloride

Larson (5) used his reagent o determine hexachlorophane n soaps.Most of the colorimetric methods were originally developed or simplephenols nd have to be adapted for chlorinated bisphenols. n general heyare nonspecific, lthough ndividual phenols o give slightly different colours.

Measurement f absorption t specific wavelengths

Lord et al (6) measured he uv absorption of bisphenols n alkalinesolution and based a method of determination on well defined maxima in

the region 300-330 nm. The absorption s determined at three wavelengths,

and a Morton and Stubbs (13) correction s applied to allow for irrelevantabsorption ue to soap. Clements nd Newburger 14) quoted methods orextracting bisphenols rom soaps nd cosmetic reparations, nd determinedthe amount present by measuring he uv absorption n alcoholic solutionat three specified wavelengths and applying appropriate corrections.

Differential absorption measurements

Mahler (15) reported hat the uv absorbance f bisphenols aries withthe state of ionisation. Childs and Parks (16) used this phenomenon odetermine hexachlorophane n liquid soap by measuring he difference nabsorption at two pH values.

Elvidge and Peutrell (17) modified he pH 8 buffer by replacing odiumhydroxide n methanol with trishydroxymethyl mino methane. he pH 8buffer was selected ecause hlorinated bisphenols re fully ionized at thispH but phenol, cresol and resorcinol re not, thereby reducing nterference.

Elvidge and Peutrell also gave extraction methods or various ypes ofcosmetic preparations.

Gas chromatographyPorcaro (18) estimated dichlorophane, hexachlorophane nd other

bisphenols y glc, using short columns 0.2-0.3 m), a temperature of 200-250C nd fast flow rates. The carrier gas was helium and the stationaryphase DC 710 (phenyl methyl silicone); under these conditions etentiontimes were between 5 and 15 min and the sensitivity 5- 10 gg.

Determination f organically ombined hlorine

Any of the standard methods an be used but the preferred method s


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216 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS

probably a Sch6niger ype combustion. his procedure annot differentiate

between hexachlorophane nd other organic compounds ontaining chlor-ine.

CONSIDERATION OF METHODS

In considering hese methods t was borne in mind that the hexachloro-phane would possibly e present n a toilet or cosmetic roduct t low evelsand that only imited equipment may be available. Other phenolic materialscould also be present, hence t was desirable o have a specific method.

All the titration methods are non-specific and therefore were notconsidered urther. Likewise the colorimetric methods are non-specificsince he differences etween he colours produced by the various phenolsare often not sufficient for characterisation.

After some of the work was started a gas chromatographic method (18)was published, but it was decided not to do any practical work becausesome members of the subcommittee did not have suitable facilities.

Nevertheless t is a specific method, which s relatively simple f the equip-ment is available.

Determination of organic chlorine s lengthy and non-specific.Measurement f uv absorption t specific wavelengths with a correction

to allow for irrelevant absorption, and the differential absorption method,which makes an allowance or absorption y other phenols ppeared worthyof further attention.

They were examined using typical cosmetic products containinghexachlorophane.

INITIAL EXPERIMENTS

Samples f an alcoholic olution, deodorant tick, a talc and a soapeach containing hexachlorophane, ere distributed amongst ix laborator-ies. Each sample was examined or its hexachlorophane ontent by twomethods:--

(1) Absorption t three specified avelengths 14), and(2) differential bsorption 17).Both papers lso describe thepreparation f samples nd hese methods

were used where appropriate.

The results or the products are summarised n Table .


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ESTIMATION OF HEXACHLOROPHANE N COSMETIC PRODUCTS 217


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218 JOURNAL F THESOCIETY F COSMETICHEMISTS

The first sample f soap had been hand-prepared, nd the hexachloro-phane had not been uniformly dispersed, o that the results showed arather wide variation. These results were discarded and instead a commercialsoap was examined y the differential bsorption ethod nly, when moreuniform results were obtained.

The difference etween he results obtained by the two methods smarginal lthough he differential ethod erhaps ends o give slightlylower results. However, members referred he latter method and resultswere slightly ess variable. Two laboratories arried out tests, and oundthat the method was quantitative or pure hexachlorophane.

STANDARDISATION OF METHOD

A discussion t this point showed hat there had been minor variationsin the preparation f samples. he method was herefore arefully ditedto avoid any further ambiguity, nd details re given n the Appendix.

THE EFFECT OF PERFUME CONTAINING PHENOLIC CONSTITUENTS

Two alcoholic olutions ere ested, one without perfume nd he otherwith a relatively high level of a number of perfumery ompounds hichcould conceivably nterfere.

The results are given in Table II.Table II

No. f No. of mean rangeaboratories results--

Non-perfumed solution0.20% w/w hexachlorophane 6 8 0.197 o 0.19-0.20

Perfumed solution0.20 % w/w hexachlorophaneand 0.$ perfume 6 8 0.200 0.19-0.22

Composition f perfumeParts

Bergamot oil 50Amyl salicylate 20Exalavende 10Cananga oil 5Orantiol 5Clove oil 5Coumarin 3Birch tar oil 2Musk D.T.I. 2

102

The results ndicated, and subsequent tatistical analysis confirmed,that interference from perfume could be neglected.


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The differential absorption curves for these two compounds werecompared ith that of hexachlorophane Fig. 1 and Table V).

Table V

Spectroscopic data

ttexachlorophaneDichlorophaneBithionol

inx nm

312307327

max cm- 1

32,05032,60030,500

approx. 1lcm144

32157

160 -

140 --

100

80

60

4O

2O

30,500 cm-I327 nm

32,050m-I/["X12 nm , ,/ \

32,600cm?

307nm

, \

\ ,,

i \\\

Hexachlorophane.... Dichlorophane

Bi'l'hionol

o oo o g o g oo o o o

trigur i Differential absorption spectra


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The curve for bithionol s sufficiently different from that of hexachloro-

phane to ensure hat it will not intefere. The maxima are much closer orhexachlorophane nd dichlorophane ut if there is a mixture the maximumabsorption ies between 307 and 312 nm according o the amounts present,e.g. a 1:1 mixture has a maximum absorption at 310 nm.

These esults ndicate that dichlorophane nd bithionol will be detected,should hese compounds e present.

DISCUSSION

The results were generally satisfactory and no account was taken of thetype of spectrophotometer sed in the collaborative ests. It was foundnecessary o standardise he procedure airly tightly to secure omparableresults. The addition of likely perfumery compounds howed hat there wasno significant nterference rom this source.

For the soap sample here was a tendency or the results to be a littlelower than expected. However, recovery of hexachlorophane added tountreated soap chips was quantitative and it is considered hat the methodis satisfactory. A different extraction procedure may be necessary or othertypes of product containing exachlorophane, .g. antiperspirant/deodorantproducts and toothpastes.

CONCLUSIONS

Inter-laboratory collaborative tests have shown that the differentialabsorption spectrophotometric ethod published by Elvidge and Peutrellis sufficiently ccurate and specific or the determination f hexachlorophanein certain toilet preparations, e.g. alcoholic solutions, alcs and soaps,containing hexachlorophane evels between 0.2% and 2%.

ACKNOWLEDGEMENTS

The Committee are grateful to the following companies nd organisa-tions who allowed heir staff time and facilities o take part in the collabora-tive work:--Beecham Products U.K., Chesebrough-Pond's td., Goya Ltd.,Givaudan & Co. Ltd., Huntingdon Research Centre, The PharmaceuticalSociety of Great Britain, and Unilever Research Laboratory- Isleworth.

(Received: 8th December 967.)


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REFERENCES

(1) Technical bulletin H 7. Sindar Corporation, U.S.A.(2) Ershov, B. P. et al., Khim. Prom. 106 (1957); Anal. Abstr. 5 1904 (1958).(3) Gottlieb, S. and Marsh, P. B. Ind. Eng. Chem. Anal. Edition 18 16 (1946).(4) Mohler, E. F. and Jacob, L. N. Anal. Chem. 29 1369 (1957).(5) Larson, H. L. J. An. Oil Chemists Soc. 28 301 (1951).(6) Lord, J. W., McAdam, I. A. and Jones, E. B. Soap Perfumery Cosmetics 6 783 (1953).(7) Achmeteli, H. I. J. Assoc. Offic. Agr. Chemists 48 278 (1960).(8) Gibbs, H. D. J. Biol. Chem. 72 649 (1927).(9) Singer, A. J. and Stern, G. R. Anal. Chem. 28 1511 (1951).

(10) Gibbs, H. D. J. Biol. Chem. 71 445 (1927).(11) Stroughton, R. W. J. Biol. Chem. 115 293 (1936).(12) Lykken, L., Treseder, R. S. and Zahn, V. Ind. Eng. Chem. Anal. Edition 18 103 (1946).(13) Morton, R. A. and Stubbs, A. L. Analyst 71 348 (1946).(14) Clements, J. E. and Newburger, S. H. J. Assoc. Oc. Agr. Chemists 117190 (1954).(15) Mahler, W. J. Am. Chem. Soc. 76 3920 (1954).(16) Childs, R. F. and Parks, L. M. J. Am. Pharm. Assoc. Sci. Ed. 45 313 (1956).(17) Elvidgc, D. A. and Peutrell, B. J. Pharm. Pharmacol. 13 Suppl. 111T (1961).(18) Porcaro, P. J. Anal. Chem. 36 1664 (1964).


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Appendix

DETERMINATION OF HEXACHLOROPHANE BY DIFFERENTIAL ABSORPTION

PrincipleHexachlorophane in solution at pH 3 (unionised) has a lower extinction value than at

pH 8 {ionised), whereas he spectra of most other constituents of the toilet preparation areunchanged. Tlxe hexachlorophane content is determined by measuring the difference inextinction which has a maximum at 312 nm.

ReagentspH 8 buffer:

Dissolve 6.07gtris-(lxydroxy-methyl) aminomethane 2 amino 2-(hydroxy-methyl) propane-1:3-diol) in 900 ml methanol. Add 50 ml 0.SN hydrochloric and make up to 1 1 with distilledwater. Nix thoroughly.

ptt 1.4 buffer:Add 18 ml glacial acetic acid and 40 ml N hydrochloric acid to 900 ml methanol. Dilute

to 1 1 with distilled water and mix thoroughly.

Preparation of samplesSoap:

Accurately weigh about 2g of soap into a 100 ml volumetric flask. Add 10 ml water andwarm gently on a water bath until dispersed (1 ml of pH 8 buffer may,be added if necessaryto prevent excessive foaming). Dilute to 100 ml with pH 8 buffer keeping the solution at30-35C. Dilute one 10 ml aliquot to 50 ml with pH 8 buffer and a second 10 ml aliquot to50 ml with pH 1.4 buffer keeping the temperature between 30 and 35C. The solutions at thisdilution should be clear and will not gel for at least 1 hr even if cooled o room temperature.Proceed with spectrophotometric determination as soon as possible.Talc:

Accurately weigh about 2g of talcum powder nto a No. 3 porosity, sintered glass crucibleor funnel. Extract the powder with 5 successive ortions of 20 ml chloroform, draw eachextract through the sinter with gentle suction and collect the combined extracts in a Buchnerflask. Transfer to a beaker and remove the chloroform on a steam bath, taking care to avoidvolatilisation of the bisphenol. This is best achieved by evaporating almost to dryness, henremoving the beaker from the bath and finishing the evaporation using a jet of compressedair. Dissolve the residue n pH 8 buffer and dilute to 100 mi. Dilute one 10 ml aliquot to 50mlwith pH 8 buffer and a second 10 ml aliquot to 50 ml with pH 1.4 buffer. Proceed with thespectrophotometric determination.Alcoholic solution:

Pipette 10 ml of the alcoholic solution into a 100 ml graduated flask and dilute to volume

with pH 8 buffer. Dilute one 10 ml aliquot to 50 ml with pH 8 buffer and a second 10 mlaliquot to 50 ml with pH 1.4 buffer.

If a w/w result is required, determine the density of the original solution or weigh a 10 mlaliquot.

Spectrophotometric determination

Place the solution made up with pH 1.4 buffer in the reference beam and the solution madeup with pH 8 buffer in the sample beam. Read the optical density over the range 290-340 nm{33,480-29,410 m-1). The maximum absorption s at approximately 312 nm (32,050 cm-1)and heE/rvaluet this wavelengths 144.

It is advisableo check heE % value nd he wavelength or maximum bsorptioncmusing a sample of pure hexachlorophane. alculate he percentage hexachlorophane rom theobserved reading.

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