Determination of Bronopol, Bronidox, and Methyldibromo Glutaronitrile in Cosmetics by Liquid Chromatography with Electrochemical Detection

A method for the simultaneous determination of methyldibromo glutaronitrile, bronopol, and broni-dox in cosmetics, based on liquid chromatography with electrochemical detection, is described. The method is suitable for both aqueous products and emulsions. The detection limit is better than 0.002% for all analytes. Recoveries from an emulsion, spiked to concentrations of 0.03% of the analytes, were 100.4% for bronopol [relative standard deviation (RSD), 0.43%], 97.1% for bronidox (RSD, 0.83%), and 98.4% for methyldibromo glutaronitrile (RSD, 1.7%). Repeatabilities were calculated from 10 replicate analyses of commercial samples. The repeatability for bronopol from an emulsion containing 0.047% bronopol was 0.0027% (RSD, 1.99%); for bronidox from a lotion containing 0.027% bronidox, 0.0014% (RSD, 1.86%); and for methyldibromo glutaronitrile from an emulsion containing 0.031% methyldibromo glutaronitrile, 0.0019% (RSD, 2.16%). A ruggedness test showed that sample amount influenced the results for all 3 analytes. The results obtained for bronidox also depended on detection parameters and composition of extraction solvent. The method was applied to 138 cosmetic products and performed trouble free during these analyses. Bronopol was found in 14 samples, and bronidox was found in 4 samples, including a baby hair lotion, in which it is prohibited. Methyldibromo glutaronitrile was present in 27 samples, including creams, lotions, and sun protection cosmetics.

Methyldibromoglutaronitrile is an important contact allergen in The Netherlands

From 15 May to 15 December 1994, 2943 patients suspected of having contact dermatitis (1955 women, 988 men) were patch tested with methyldibromoglutaronitrile 0.3%, 0.1% and 0.05% pet. 119 patients (4.0%; women 4.1%, men 3.8%) proved to be allergic. 71% of the reactions were considered to be relevant. In 2/3 of the patients, causative products were cosmetics, in 1/3 moistened toilet tissues. Testing with methyldibromoglutaronitrile at lower concentrations (0.05% and 0.1%) and with commercial allergens (Euxyl K 400 and methyldibromoglutaronitrile, both containing methyldibromoglutaronitrile 0.1%), resulted in a number of false-negative reactions. All preservatives in the European standard series had lower scores than the 4% positive reactions to methyldibromoglutaronitrile (formaldehyde 2.0%, MCI/MI (Kathon CG) 3.2%, parabens 1.0%, quaternium-15 1.3%). It is concluded that methyldibromoglutaronitrile (present in the commercial preservative Euxyl K 400) is an important contact allergen in the Netherlands in cosmetics and moistened toilet tissues. It should be added to cosmetics series and to proctological series. The optimal test concentration is unknow, but may be 0.3% pet. The concentration of 0.1% methyldibromoglutaronitrile in the currently available commercial allergens appears to be too low, resulting in a number of false-negative reactions.

Contact allergy to cocamidopropyl betaine

Cocamidopropyl betaine is an amphoteric surfactant used increasingly in cosmetic products. We describe 20 cases of cosmetic allergy to cocamidopropyl betaine; all were caused by shampoo or shower gel. 8 patients were hairdressers, who had occupational allergic contact dermatitis from shampoos. We recommend patch testing cocamidopropyl betaine 1% aq. routinely in hairdressers with dermatitis of the hands, and in all patients suspected of suffering from cosmetic allergy.

Determination of methyldibromoglutaronitrile in cosmetic products by high performance liquid chromatography with electrochemical detection

Synopsis A method for the determination of methyldibromoglutaronitrile in cosmetic products is described. Reversed phase high performance liquid chromatography and reductive electrochemical detection is employed to provide for improved selectivity and detectability compared to alternative methods. The method detects 0.002% methyldibromoglutaronitrile in cosmetic products and has a linear range from 0.006 up to 0.06%, which can easily be extended to the legally allowed limit of 0.1% by means of a simple dilution step. At a level of 0.03% the coefficient of variation was estimated to be 1.7%. Recoveries measured were between 98 and 100%. The method has been subjected to a ruggedness test, which indicated that it was stable, but slightly sensitive for a decrease in the detection potential. More than 130 cosmetic products have been analysed using the method. In 19 samples methyldibromoglutaronitrile was detected in concentrations varying between 0.002% and 0.030%. Résumé Une méthode a été mise au point pour la détermination du methyldibromoglutaronitrile, un conservateur cosmétique dont l'utilisation est croissante. La méthode utilise la chromatographie liquide à haute performance avec détection électrochimique pour permettre une amélioration de la détection et de la spécificité. Selon une procédure simple, le methyldibromoglutaronitrile est séparé sur une colonne 100 RP8 (lichosphere MERCK) avec une phase mobile constituee d'eau et d'acétone (60/40 v/v) avec un ajout de sulfate de sodium et du chlorure de sodium pour obtenir des concentrations de 0.02 M et 0.002 M respectivement. Une électrode en or a été utilisée pour la détection avec un potentiel de fonctionnement de -0.6 V réductif. Une détection par pulsation a été nécessaire pour obtenir une réponse stable. Le détecteur a été programmé pourgarder l'électrode pour 10 ms à 1 V, 10 ms à-1 V (réductif) et à-0.6 V pour 100 ms, ce potentiel a été utilisé comme mesure. Des courbes de calibration linéaire ont été obtenues sur une gamme de 0.006%à 0.06% methyldibromoglutaronitrile. Une concentration de 0.002% de methyldibromoglutaronitrile a pu être détectée par un rapport signal/bruit supérieur à 2,5. La reconstitution d'un échantillon, doséà 0.03% de methyldibromoglutaronitrile a atteint 98% d'après les mesures sur la surface des pics et 100% en calculant la hauteur des pics. La déviation relative calculée sur des éxpériences d'extraction indépendantes à partir du même échantillon dosé a été estimée à 1.7%. La méthode a été soumise à un test de robustesse. Les divers paramétres étaient les suivants: la quantité d'échantillons soumis à l'analyse; le temps d'extraction et le temps durant lequel la solution extraite a été mélangée; la composition du solvant d'extraction; la température de la colonne; le temps de pulsation du détecteur et le potentiel de fonctionnement.

[Replacement of Kathon CG by Euxyl K 400 in cosmetics; from the frying pan into the fire?]

The recent negative publicity on the cosmetics preservative Kathon CG has made many cosmetic manufacturers look for safer alternatives. The most popular substitute appears to be Euxyl K 400, containing phenoxyethanol and methyldibromoglutaronitrile. Unfortunately, this preservative also induces allergic reactions to cosmetics and (at least in the Netherlands) to 'moist toilet paper'. Therefore, in cases of apparent reactions to cosmetics and of eczema ani, allergy to methyldibromoglutaronitrile should be suspected. Testing the finished products often results in false-negative reactions, and consequently the allergen (suggested concentration 0.05% in petrolatum) should preferably be tested separately.

Allergic contact dermatitis from tocopheryl acetate in cosmetic creams

4 cases of cosmetic allergy to tocopheryl acetate are reported. The literature on contact allergy to vitamin E and its derivatives is reviewed.

[Peri-anal allergic contact eczema with dyshidrotic eczema of the hands due to the use of Kathon CG moist toilet wipes]

Two cases of dyshidrotic eczema of the hands caused by perianal allergic contact dermatitis due to Kathon CG in moist toilet paper are described.

Cosmetic allergy to the UV-absorber bornelone

Two cases of contact allergy to the UV-absorber bornelone in cosmetic products are presented. The literature on (photo)contact allergy to sunscreens is reviewed.

Cross-reaction pattern of the cationic emulsifier oleamidopropyl dimethylamine

13 patients allergic to the cationic emulsifier oleamidopropyl dimethylamine were tested with a series of related amide-amine type surfactants in order to investigate its cross-reaction pattern. With 1 exception, all patients reacted to at least 4 of the test materials. Most reactions were observed to ricinoleamidopropyl dimethylamine lactate and tallowamidopropyl dimethylamine (11 patients, 85%); 9 patients (of 12 tested, 75%) reacted to lauramidopropyl dimethylamine and 6 (46%) to myristamidopropyl dimethylamine. A certain pattern of cross-reactivity was recognised.

The allergens in cosmetics

The ingredients responsible for allergy to cosmetics were determined in 119 patients suffering from cosmetic-related contact dermatitis. Most reactions (56.3%) were caused by skin care products, followed by nail cosmetics (13.4%), perfumes (8.4%), and hair cosmetics (5.9%). Preservatives were most frequently implicated (32.0%), followed by fragrances (26.5%) and emulsifiers (14.3%). By far the most important cosmetic allergen was Kathon CG, (a preservative system containing, as active ingredients, a mixture of methylisothiazolinone and methyl chloroisothiazolinone) reacting in 33 patients (27.7%). Other frequent causes of cosmetic-related contact allergic reactions were toluenesulfonamide/formaldehyde resin in nail hardener and/or nail lacquer (15 patients [12.6%]), and oleamidopropyl dimethylamine, an emulsifier in baby body lotion (13 patients [10.9%]).

An outbreak of contact dermatitis from toluenesulfonamide formaldehyde resin in a nail hardener

8 cases of contact dermatitis from toluenesulfonamide formaldehyde resin in a nail hardener are presented. Most patients had used nail lacquers containing this resin for many years without trouble, but became sensitized to the resin shortly after the introduction of this particular nail hardener. A hypothesis concerning the possible mechanism is given.

Contact allergy to diazolidinyl urea (Germall II)

4 cases of contact allergy to diazolidinyl urea (Germall II) in a "hypoallergenic" brand of cosmetics are described. 2 patients sensitized by these cosmetics were not allergic to formaldehyde. 2 other patients already sensitive to formaldehyde had exacerbations of dermatitis due to diazolidinyl urea. The following tentative conclusions were drawn. (i) Contact allergy to diazolidinyl urea may or may not be due to formaldehyde sensitivity. (ii) Patients allergic to formaldehyde may suffer contact allergic reactions from the use of cosmetics containing diazolidinyl urea. (iii) Patients sensitized to diazolidinyl urea may cross-react to imidazolidinyl urea and vice-versa. (iv) It is suggested that the sensitizing potential of diazolidinyl urea is greater than that of imidazolidinyl urea. (v) Aq. solutions may be preferable to pet. for patch testing with diazolidinyl urea.

Patch test reactivity to DMDM hydantoin. Relationship to formaldehyde allergy

The relationship between contact allergy to formaldehyde and positive patch test reactions to DMDM hydantoin was investigated. 35 formaldehyde-allergic patients were patch tested with serial dilutions of formaldehyde (0.1%-0.3%-1.0% aq.) and DM hydantoin (the non-formaldehyde-containing parent compound of DMDM hydantoin). 21 were also patch tested with MDM hydantoin (1 molecule formaldehyde) in serial dilutions: 7 (33%) reacted to 1 or more concentrations. The other 14 were also tested with DMDM hydantoin (2 molecules formaldehyde) in serial dilutions: 8 (57%) reacted to 1 or more concentrations. Patients patch-test-positive to formaldehyde 0.1% and/or 0.3% tended to show more patch test reactivity to (D)MDM hydantoin than those who reacted only to 1%. Aqueous solutions of (D)MDM hydantoin in concentrations as used in cosmetic products therefore contain enough free formaldehyde to cause dermatitis in a patch test system in some formaldehyde-allergic patients: 12 such patients applied a cream containing 1% DMDM hydantoin to the flexor aspect of the lower arm twice daily for 1 week; 4 (33%) developed dermatitis. The use of a cream containing 0.25% DMDM hydantoin in these 4 patients still caused dermatitis in 1 and provoked itching in another. An increase in the use of DMDM hydantoin in cosmetic products will also inevitable increase the risk of cosmetic dermatitis in consumers allergic to formaldehyde.

Kathon CG: a review

Kathon CG, a cosmetics preservative containing, as active ingredients, 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one, appears to be a frequent cause of contact dermatitis in Europe. In the United States, where Kathon CG was introduced some 5 years later, the use of this preservative system for cosmetics and toiletries is rapidly increasing. Undoubtedly cases of contact sensitization will soon emerge in this country. Most cases of contact allergy are caused by the use of moisturizing creams on (slightly) damaged skin. Sensitization by the use of cosmetic products on previously healthy skin, especially the face, does occur but appears to be less frequent. Rinse-off products do not seem to have a substantial potential for the induction and elicitation of contact allergic reactions to Kathon CG because of dilution of the product and the allergen with water as well as a short contact time with the skin. This review provides a synopsis of current knowledge on the preservative system Kathon CG, with emphasis on the risk of sensitization and diagnostic procedures.

Contact allergy to 4-isopropyl-dibenzoylmethane and 3-(4'-methylbenzylidene) camphor in the sunscreen Eusolex 8021

10 cases of contact allergy from the sunscreen Eusolex 8021 are reported. 5 patients were sensitized to a lipstick, 4 to a sunscreen cream, and 1 reacted to several cosmetic creams. Of 9 patients tested with the 2 ingredients of Eusolex 8021, 5 proved to be allergic to both (chemically unrelated) constituents: 4-isopropyl-dibenzoylmethane and 3-(4'-methylbenzylidene) camphor; 4 were allergic to 4-isopropyl-dibenzoylmethane only. Contact allergy to this recently introduced broad spectrum sunscreen may not be rare. The relevant literature is reviewed.

Contact allergy to preservatives--II

To determine whether the prevalence of allergic reactions to certain preservatives warrants their inclusion in a routine series for patch testing, a tray of 14 preservatives was tested in 501 consecutive suspected contact dermatitis patients. More than 1% positive reactions were found with DMDM hydantoin, Kathon CG, and alkyl trimethyl ammonium chloride only. The concentration of alkyl trimethyl ammonium chloride (0.1% aqua) was considered too high. Of 6 patients reacting to the formaldehyde releaser DMDM hydantoin, 4 were positive to formaldehyde. Kathon CG may be an important allergen in the Netherlands, and it is worthwhile for dermatologists there to add it to the standard test series. The recent inclusion of quaternium-15 in the ICDRG standard series appears to be of little value to them.

Kathon CG: cosmetic allergy and patch test sensitization

Three cases of contact allergy to Kathon CG, a preservative for cosmetics and toiletries containing, as active ingredients, 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one are presented. In two patients, Kathon CG was contained in a moisturizing cream, and the third was sensitized by a diagnostic patch test. Although it has been used extensively in cosmetics and toiletries for 9 years in Europe and 4 years in the USA, these appear to be the first case reports of non-occupational sensitization to Kathon CG.

Development and optimization of pharmaceutical formulations using a simplex lattice design

The composition of pharmaceutical formulations is often subject to trial and error. This approach is time consuming and unreliable in finding the best formulation. Optimization by means of an experimental design might be helpful in shortening experimenting time. Such a design with the concomitant mathematical models, reveals effects and interactions of the variables. The independent variables are the different compositions of the mixtures of the chosen ingredients [drug(s) and excipients]. The dependent variables are the properties (responses) of the formulation. When all responses of interest have been expressed in models that describe the response as a function of the composition of the mixture, the models can be combined graphically or mathematically to find a composition satisfying all demands. In this paper an introduction to the use of mixture designs will be given by means of a theoretical part and an example: optimizing a tablet formulation consisting of excipients only.

Reversed-phase high-performance liquid chromatographic separation of saccharin, caffeine and benzoic acid using non-linear programming

A method is described which allows a chromatographic assay to be optimized with respect to the time needed to complete an analysis, while maintaining good resolution. The method introduces an operational research technique called linear programming. It was used to optimize the eluent composition for the assay of saccharin, caffeine and benzoic acid and resulted in a significant reduction in the analysis time.