Ethyl paraben

A mixture of methyl paraben, ethyl paraben, propyl paraben, diethyl phthalate, and butyl paraben is separated by HPLC. This experiment emphasizes the development of a mobile-phase composition capable of separating the mixture. A photodiode array detector demonstrates the coelution of the two compounds. 

Parabens are approved for use in oral solution and suspensions at a concentration of 0.015% to 0.2% w/v. Due to their low solubility, the sodium salts of parabens are often used in aqueous formulations. The parabens are most effective in the pH range of 2 to 6, and their antimicrobial activity decreases with increasing pH. Additionally, they are very unstable at pH 8 or above in solution. Methyl paraben has also demonstrated incompatibility with sorbitol and may show some discoloration in the presence of iron. The absorption of methylparaben by plastics has been reported with the amount absorbed being dependent upon the type of plastic and vehicle. However, no absorption has been reported for low density polyethylene (LDPE) or high density polyethylene (HDPE) containers. Certain coloring agents such as yellow iron oxide, ultramarine blue, and aluminum silicate can extensively absorb ethyl paraben in simple aqueous systems, thus reducing its preservative efficacy. 

Preservative agents are added to injectable preparations when multiple dosing is expected out of the same unit. Examples of preservatives used in injectable preparations include phenol, benzyl alcohol, methyl and ethyl parabens, and benzalkonium... 

It has been reported that a 1 1 nicotinamide and ethyl paraben (ethyl 4-hydroxybenzoate) cocrystal can be crystallized from ethanol, with the crystal structure being used to demonstrate that both reactant molecules form corrugated layers within the cocrystal that are linked by extensive hydrogen bonding [55]. While excess amounts of nicotinamide serve to enhance the solubility of ethyl paraben somewhat, the cocrystal exhibits lower solubility in water with respect to the reactant species, and will precipitate from aqueous solutions at ambient temperature. 

S. Nicoli, S. Bilzi, P. Santi, M.R. Caira, J. Li, R. Bettini, Ethyl-paraben and nicotinamide mixtures apparent solubility, thermal behavior and X-ray structure of the 1 1 cocrystal, J. Pharm. Sci. 97 (2008) 4830-4839. 

Bulk/tablets Ethambutol HPLC ISTD-ethyl paraben, powder, glass beads, mobile phase Cg, Zorbax P04 (6.8 g/730 m y-CH3CN (730 270), 1 ml/min 210 nm Method review, resolve equilin sulfate, estrone sulfate along with other conjugates history [478] fluorodensi-tometry [480] USP 23 [5] HPLC [880-882] [479]... 

Figure 18-12. Separation of test mixture and fractions after extraction and trapping and sequential elution at increasing temperatures. Separation on PS-DVB column at 75-185°C at 15°C/min. Analytes 1, paracetamol 2, salicylamide 3, caffeine 4, methyl paraben 5, phenacetin 6, ethyl paraben. Separations a, direct injection of original mixture of 1-6 without trapping b, fraction untrapped at ambient temperature c, fraction released from trap at 70°C d, released at 90°C e, released at 110°C. (Reproduced from reference 76, with permission from Royal Society of Chemistry.)...

SYNS ASEPTOFORM E BONOMOLD OE p-CAR-BETHOXYPHENOL EASEPTOL ETHYL-p-HYDRO-XYBENZOATE ETHYL PARABEN ETHYL PARA-SEPT p-HYDROXYBENZOIC ETHYL ESTER NIP-AGIN A NIPAZIN A p-OXYBENZOESAEUREAETH-YLESTER (GERMAN) SOLBROL A TEGOSEPT E... 

ETHYLOXYPHENOL see EFAIOO ETHYL PABATE see EEKIOO ETHYL PARABEN see HJLOOO ETH T PARASEPT see HJLOOO ETHYL PARATHION see PAKOOO ETHYL PELARGONATE see ENWOOO... 

Figure 15.1 Comparison of experimental (solid lines) and predicted (dotted lines) gradient elution profiles for ethyl paraben. Gradient from 30 to 60% (v/v) methanol in water, in 15 min., at 2.5 mL/min. Vp is the volume of sample injected and Cp the feed concentration (0.008 g/1). Reproduced with permission from G. Carta, W. B. Stringfield, J. Chromatogr., 605 (1992) 151 (Fig. 8).

Name Ethyl Paraben Calibration Id 1502 Fit Type Linear (1st Order) R 0.999950 RA2 0.999900... 

Figure 10.5. HPLC chromatogram of ethyl paraben used as a reference application for problem diagnostics. The inset shows the HPLC conditions and the typical performance parameters such as plate count, pressure, and retention time.

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

Uniphen P-23. [Induchem AG Lipo] Phenoxyethanol methylparaben, ethyl-paraben, pnq>ylparaben, butylparabm. 

Simultaneous guaifenesin, pseudoephedrine, pholcodine, methyl paraben, ethyl paraben, propyl paraben, butyl paraben... 

Simultaneous acetaminophen, butyl ptiraben, ethyl paraben, methyl paraben, pholcodine, propyl paraben, pseudoephedrine... 

Abuiijeie, M.A. el-Din, M.S. Mahmoud, LI. Determination of theobromine, theophylhne and caffeine in various food products using derivative UV-spectrophotometric techniques and high-performance liquid chromatography. J.Liq.Chromatogr., 1992, 15, 101-125 [ethyl paraben (IS)]... 

Talcoseptic C. [Vevy] Talc, phen-oxyethanol, methylparaben, ethyl-paraben, propylpar en, bu lparaben. 

HYDROXYBENZOATE ETHYL PARABEN ETHYL PARASEPT p-HYDROXYBENZOIC ETHYL ESTER... 

Jermini, M.F.G. and Schmidt-Lorenz, W., Activity of Na-benzoate and ethyl-paraben against osmotoler-ant yeasts at different water activity values, J. Food Protect., 50, 920, 1987. 

To highlight the method development plan, we will look at a series of preservatives known as parabens. These preservatives are used in the cosmetic, pharmaceutical, and food industries and are effective antifungal and antimicrobial agents. Antifungal and antimicrobial activity increases with increasing chain length. Methyl and propyl parabens can be added directly to foodstuffs in most countries, and ethyl paraben is permitted in some countries. They can be incorporated into foods at a maximum level of 0.1%. Parabens do occur naturally, but those used in industry are synthetic analytes produced by the esterification of parahydroxbenzoic acid with a suitable alcohol. For example, methanol would be used in the manufacture of methyl parahydroxybenzoate. We have chosen to look at a subsection of the paraben series that includes... 

FIGURE 15.2 (a) Ion mobility spectrum of a standard solution of methylparaben, ethyl-paraben, propelparaben, butylparaben, and benzylparaben. (b) IMS spectrum of a sample blank. (C) IMS spectrum of a topical cream showing the presences of parabens at the level of approximately 1 mg/g. (From Lokhnauth and Snow, Determination of parabens in pharmaceutical formulations by solid-phase microextraction-ion mobility spectrometry. Anal. Chem. 2005,77, 5938-5946. With permission.)... 

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