Parabens Methylparaben Propylparaben

Preservatives. Most products must contain preservatives to ensure that yeasts, molds, and bacteria do not thrive in them. These preservatives include alcohol, methylparaben, propylparaben, DMDM hydantoin, diazohdinyl urea, and imidazohdinyl urea. The parabens have limited solubiUty in water, eg, 0.25% for methylparaben and 0.05% for propylparaben (22). If these levels are exceeded in the formula, then the addition of solvents is needed to ensure clear, stable products. 

The most frequently used antimicrobials found in commercial shampoos are parabens, methylparaben and propylparaben. Mixtures of different preservatives provide broader protection against a wider spectrum of microorganisms and have been proven to be the most effective method to ensure product robustness [100], The level of preservative necessary depends on the composition of ingredients, total alcohol level, pH value, and water activity. 

Preservatives Parabens (methylparaben, ethylparaben, butylparaben, propylparaben, etc.), EDTA, Formaldehyde, Quaternium 15, Methylisothiazolinone Skin irritation and allergic reactions. Can be neurotoxic. Some, like parabens, are suspected hormone disrupters. Also found in all cosmetics and toiletries. 

Lauramidopropyl PEG-dimonium chloride phosphate Lauroampho PEG-glycinate phosphate Potassium butyl paraben Potassium ethylparaben Potassium methyl paraben Potassium propylparaben Potassium sorbate Sodium butylparaben Sodium ethylparaben Sodium methylparaben Sodium propylparaben Sucrose myristate bactericide, photographic film Cocamidopropyl hydroxysultaine N,N-Dimethyl-N-lauric acid-amidopropyl-N-(3-sulfopropyl)-ammonium betaine N,N-Dimethyi-N-myristyi-N-(3-suifopropyi)-ammonium betaine N,N-Dimethyi-N-paimityi-N-(3-suifopropyi)-ammonium betaine N,N-Dimethyi-N-stearyi-N-(3-suifopropyi)-ammonium betaine... 

Sodium 2-mercaptobenzothiazole Sodium pentachlorophenate Sodium o-phenylphenate Sodium salicylate Thymol Tributyltin acetate Tributyltin oxide Zinc dimethyidithiocarbamate Zinc 2-mercaptobenzothiazole preservative, food-packaging materials Methylparaben Propylparaben preservative, fruit drinks Heptyl paraben... 

Fig. 10.5. Separation of parabens with the poly(TBAAm-co-AMPS)-coated column. Conditions column, 750 mm x 25 pm i.d. (600 mm effective length) mobile phase, 20% acetonitrile (v/v) in 50 mMTris-HCl buffer field strength, 400 V/cm injection, 12 kV for 3 s at the side of the anode detection wavelength, 254 nm. Peak identification 1, methylparaben 2, ethylparaben 3, propylparaben 4, butylparaben 5, amylparaben. Reproduced with permission from Sawada and Jinno [11].

The activity of the parabens increases with increasing chain length of the alkyl moiety, but solubility decreases. Activity may be improved by using combinations of parabens since synergistic effects occur. Ethylparaben is commonly used with methylparaben and propylparaben in oral and topical formulations (such mixtures are commercially available for example, Nipasept (Nipa Laboratories Inc.). Activity has also been reported to be improved by the addition of other excipients see Methylparaben for further information. 

Methylparaben and propylparaben are affirmed GRAS Direct Food Substances in the USA at levels up to 0.1%. All esters except the benzyl ester are allowed for injection in Japan. In cosmetics, the EU and Brazil allow use of each paraben at 0.4%, but the total of all parabens may not exceed 0.8%. The upper limit in Japan is 1.0%. 

Propylparaben and methylparaben have been used as preservatives in injections and ophthalmic preparations however they are now generally regarded as being unsuitable for these types of formulations owing to the irritant potential of the parabens. 

Cosmetic Ingredient Review. 1984. Final report on the safety assessment of methylparaben, ethyl-paraben, propylparaben, andbutylparaben./. Amer. Col. Toxicol. 3 147-209. 

Prepfos. See Pentasodium triphosphate Preserval B. See Benzyl paraben Preserval Butilique. See Butylparaben Preserval E. See Ethyl paraben Preserval M. See Methylparaben Preserval P. See Propylparaben Press-Aid SP] Press-Aid XP. See Synthetic wax... 

Benzylparaben Potassium butyl paraben Potassium ethylparaben Potassium propylparaben Sodium butylparaben Sodium ethylparaben Sodium methylparaben Sodium propionate Sodium propylparaben Sorbic acid Thiabendazole... 

Potassium propionate Potassium propylparaben Potassium salicylate Potassium sorbate Potassium sulfite Propionic acid Propyl benzoate Propylparaben Quatemium-15 Salicylic acid Silver borosilicate Silver chloride Silver magnesium aluminum phosphate Sodium benzoate Sodium bisulfite Sodium butylparaben Sodium dehydroacetate Sodium ethylparaben Sodium formate Sodium hydroxymethylglycinate Sodium iodate Sodium metabisulfite Sodium methylparaben Sodium paraben Sodium o-phenylphenate... 

Phenylmercuric borate Phenylmercuric nitrate Potassium benzoate Potassium bisulfite Potassium butyl paraben Potassium caroate Potassium ethylparaben Potassium lactate Potassium metabisulfite Potassium methylparaben Potassium propylparaben Potassium salicylate Potassium sorbate Potassium sulfite Propionic acid Propylene glycol Propyl gallate Propylparaben Salicylic acid Sodium ascorbate... 

Other regulatory bodies such as the U.S. FDA (Food and Drug Administration) have set the limit of methylparaben and propylparaben at 0.1% w/w. In cosmetics, the EEC and Danish cosmetic regulations give a combined maximum limit of 0.8% w/w for all the parabens. Various regulatory bodies set the maximum levels of all the parabens in pharmaceutical products at 1% w/w [3]. For this reason, robust analytical methods are required for the determination of parabens in a variety of matrices. 

Zhang et al. [21] used the HPLC-flow injection chemiluminescence method to determine methylparaben, ethylparaben, propylparaben, and butylparaben, based on the same chemiluminescence enhancement reaction by parabens of the cerium(IV)-rho-damine 6G system in sulfuric acid. The method was applied to orange juice, soy sauce, vinegar, and cola soda (Table 10.1). The advantage of this technique is that it showed greater sensitivity and wider dynamic linear ranges than the electrochemical and fluo-rometric detectors [21]. 

Hydroxyhenzoic acid, isodecyl ester. See Isodecyl paraben 4-Hydroxybenzok acid, methyl ester. See Methylparaben 4-Hydroxybenzok acid, propyl ester p Hydroxybenzok acid, propyl ester. See Propylparaben... 

---