Preservatives Propyl 4-hydroxybenzoate

At pH 7-8 methylparaben is less stable and also less effective. Propyl hydroxybenzoate can be added to increase the preservative effect. If the pH > 8, methylparaben is of no use any more. 

Methyl hydroxybenzoate has an unfavourable partition coefficient. Therefore it is not a suitable preservative for o/w emulsions. It is mainly used in hydrogels. In some countries a combination with propyl hydroxybenzoate is used as Preserved water . A typical mixture contains 0.075 % of methyl parahydroxybenzoate and 0.025 % of propyl parahydroxybenzoate in purified water. 

The use of preservative eombinations may be used to extend the range and speetrum of preservation. Thus, in the series of alkyl esters of 4-hydroxybenzoic (/ -hydroxybenzoic) acid (parabens), water solubility deereases in the order methyl, ethyl, propyl and butyl ester. By eombining these produets it is possible to aehieve a situation where both the aqueous and oil phase of an emulsion are proteeted. 

Annex III lays down the conditions of use for permitted preservatives and antioxidants, with lists of foods and maximum levels in each case. Part A lists the sorbates, benzoates and p-hydroxybenzoates, E 200-E 219 part B lists sulphur dioxide and the sulphites, E 220-E 228 part C lists other preservatives with their uses, including nisin, dimethyl dicarbonate and substances allowed for surface treatment of certain fruits, E 249 potassium nitrite, E 250 sodium nitrite, E 251 sodium nitrate and E 252 potassium nitrate, E 280-E 283 propionic acid and the propionates part D lists the antioxidants E 320 butylated hydroxyanisole (BHA), E 321 butylated hydroxytoluene (BHT), E 310 propyl gallate, E 311 octyl gallate, E 312 dodecyl gallate, E 315 eiythorbic acid and E 316 sodium erythorbate. 

There is a recent trend towards simultaneous CE separations of several classes of food additives. This has so far been applied to soft drinks and preserved fruits, but could also be used for other food products. An MEKC method was published (Lin et al., 2000) for simultaneous separation of intense sweeteners (dulcin, aspartame, saccharin and acesulfame K) and some preservatives (sorbic and benzoic acids, sodium dehydroacetate, methyl-, ethyl-, propyl- and isopropyl- p-hydroxybenzoates) in preserved fruits. Ion pair extraction and SPE cleanup were used prior to CE analysis. The average recovery of these various additives was 90% with good within-laboratory reproducibility of results. Another procedure was described by Frazier et al. (2000b) for separation of intense sweeteners, preservatives and colours as well as caffeine and caramel in soft drinks. Using the MEKC mode, separation was obtained in 15 min. The aqueous phase was 20 mM carbonate buffer at pH 9.5 and the micellar phase was 62 mM sodium dodecyl sulphate. A diode array detector was used for quantification in the range 190-600 nm, and limits of quantification of 0.01 mg/1 per analyte were reported. The authors observed that their procedure requires further validation for quantitative analysis. 

Preservative 217 Sodium propyl p-hydroxybenzoate 10 35th Series 2001... 

Liquid dosage forms which are disperse systems (colloidal, i.e., microspheres, nanoparticles, and micelles suspensions and emulsions) often contain preservatives which are methyl, ethyl, propyl, and butyl esters of para-hydroxybenzoic acid in various combinations. A typical example is the antacid suspensions which have high pH values which make the esters of the preservatives susceptible to hydrolysis. One way to circumvent this problem is to use several preservatives in combination with the hope that some quantities of the preservatives will remain to prevent the suspension from microbial attack. A report showing the assay of the four esters and the parent acid (one of the decomposition products) in drug products in which all the preservatives were used has been given [13]. 

This part of the chapter describes HPLC techniques for the separation and determination of preservatives, as follows S02, postharvest preservatives (PPs), benzoic acid (BA), sorbic acid (SA), and the ethyl, methyl, propyl esters of 4-hydroxybenzoic acid (EsHBA) and 5-nitrofury-lacrylic acid (5-NFA). The propionic, lactic, acetic acids are discussed in the chapter on organic acids. 

A paired-ion, reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of sweeteners (dulcin, saccharin-Na, and acesulfame-K), preservatives (sodium dehydroacetate, SA, salicyclic acid, BA, succinic acid, methyl-para-hydroxybenzoic acid, ethyl-para-hydroxybenzoic acid, n-propyl-para-hydroxybenzoic acid, n-butyl-para-hydroxybenzoic acid, and isobutyl-para-hydroxybenzoic acid), and antioxidants (3-tertiary-butyl-4-hydroxyanisole and tertiary-butyl-hydroquinone). A mobile phase of acetonitrile-50 ml aqueous tr-hydroxyisobutyric acid solution (pH 4.5) (2.2 3.4 or 2.4 3.6, v/v) containing 2.5 mM hexadecyltrimethylammonium bromide and a Clg column with a flow rate of 1.0 ml/min and detection at 233 nm were used. This method was found to be very reproducible detection limits ranged from 0.15 to 3.00 p,g. The retention factor (k) of each additive could be affected by the concentrations of hexadecyltrimethylammonium bromide and a-hydroxyisobu-tyric acid and the pH and ratio of mobile phase. The presence of additives in dried roast beef and sugared fruit was determined. The method is suitable for routine analysis of additives in food samples (81). 

Prochlorperazine Edisylate Prochlorperazine edisylate is not compatible with sodium chloride solutions containing methyl hydroxybenzoate and propyl hydroxy-benzoate as preservatives, but is compatible with solutions containing benzyl alcohol. Prochlorperazine edisylate salts are incompatible with a number of drugs such as aminophylline, amphotericin, ampicillin sodium, some barbiturates, ben-zylpenicillin salts, calcium gluconate, cefmetazole sodium, cephalothin sodium, chloramphenicol sodium succinate, chlorothiazide sodium, chloramphenicol, morphine sulfate containing phenol, magnesium trisilicate mixture, sodium succinate, chlorothiazide sodium, dimenhydrinate, heparin sodium, hydrocortisone sodium succinate, midazolam hydrochloride, and some sulfonamides.166... 

SYNS ASEPTOFORM P BETACIDE P BONOMOLD OP 4-HYDROXYBENZOIC ACID PROPYL ESTER p-HYDROXYBENZOIC ACID PROPYL ESTER NIPASOL p-OXYBENZOESAEUREPRO-PYLESTER (GERMAN) PARABEN PARj SEPT PASEPTOL PRESERVAL P PROPYL p-HYDROXY-BENZOATE n-PROP X p-HYDROXYBENZOATE PROPYLPARABEN (FCC) PROPYLPARASEPT PROTABEN P TEGOSEPT P... 

Methyl and propyl esters of p-hydroxybenzoates have been employed as preservatives for many years, particularly in eye-drops. There is still a question mark over their efficacy against Ps. aeruginosa, particularly since it has been demonstrated that the organism can utilise them as a carbon source [54]. Concentrations in the region of 1000 pg/ml have been shown to be effective but other reports suggest that parebers are almost inactive against Ps. aeruginosa [55]. 

Certain preservatives are physically unstable with certain macromolecules.For example, adsorption of methyl p-Hydroxybenzoate to nylon was found to be dependent on nylon membrane size and the concentration of free methylparaben. The complexation of methyl p-Hydroxybenzoate with Tween 80 depends on the amount of free methylparaben and the concentration of Tween 80. Similar results have been reported for propyl p-Hydroxybenzoate. 

Acidic preservatives are the most widely used for oral preparations, such as the p-Hydroxybenzoic acid esters and salts of benzoic acid. These are adequately soluble in aqueous systems and possess both antifungal and antibacterial properties. Methyl and propyl p-hydroxybenzoic acid are often used together in a 10 1 ratio. Concomitant use of multiple esters makes possible a higher total preservative concentration owing to the independent solubilities of each and, according to some researchers, maximizes the antimicrobial effect. 

Parabens (methyl, ethyl, propyl, and butyl esters of para-hydroxybenzoic acid) are used as preservatives in concentrations of 0.1-0.3% in pharmaceutical formulations and in concentrations of 0.01-0.1% in cosmetics and foods. In such concentrations they are devoid of systemic toxic effects, but allergic reactions have been reported. 

The alkyl esters (methyl, ethyl, and propyl) of p-hydroxybenzoic acid (the parabens) are widely used for their antifungal properties. The preservative effect of parabens tends to increase with increasing molecular mass. The methyl ester appears to be more effective against molds, whereas the propyl ester is more effective against yeasts (favored for oils and fats, for solubility reasons) (Gonzalez, Gallego, and Valcarcel, 1998). 

Phenol acids are phenols in which there is also a carboxylic acid group attached to the benzene ring. They include salicylic acid (ortho-hydroxybenzoic acid) and para-hydroxy-benzoic acid (Figure 25.8). Acetylsalicylic acid (aspirin) and sodium salicylate are derivatives of salicylic acid. Like phenol, they have antipyretic and analgesic properties. The methyl, ethyl and propyl esters of para-hydroxybenzoic acid (parabens) are used as preservatives in pharmaceuticals, cosmetics and foodstuffs. 

Benzoic xid, 4-hydroxy-, propyl ester, sodium salt Caswell No. 714A EINECS 252488-1 EPA Pesticide Chemical Code 061204 4-Hydroxybenzoic acid, propyl ester, sodium salt Nipasol M Sodium Parasept Propyl p-hydroxybenzoate, sodium salt Propylparaben sodium Propylparaben, sodium salt Sodium 4-propoxy-carbonylphenoxide Sodium propylparaben. Preservative, bactericide, fungicide for pharmaceuticals, cosmetics, foods, medicinal preparations, industrial applications. Laboratories Ltd Nipa. 

E216 /7-Hydroxybenzoic propyl From benzoic acid Preservative Similar to E 214 Similar to E 214... 

A gas chromatographic method may be employed for analysis for both benzoic acid and sorbic acid in food, as described in AOAC method 983.16. The acids are extracted from an acidified aqueous homogenized food sample into ether. The acids are then extracted from the ether solution into aqueous alkali, and after acidification they are re-extracted into dichloromethane. Treatment of the residue with N-methyl-N-trimethylsilyltrifluoroacetamide converts the benzoic and sorbic acids into trimethylsilyl esters. These esters are then analyzed with a glass column packed with a support coated with OV-1, in a temperature programmed analysis. Phenylacetic and caproic acids are used as internal standards for benzoic and sorbic acids, respectively. An LC method has also been described for analysis of benzoic acid with simultaneous determination of sorbic acid, and methyl, ethyl, propyl, and butyl p-hydroxybenzoates. The preservatives were extracted from meat or seasonings with 70% ethanol, and analyzed by reversed-phase LC using a Cig stationary phase with a linear gradient from 10 to 70% methanol in 1.5% aqueous ammonium acetate and 1.5% aqueous acetic acid. 

The Kolbe-Schmitt reaction of potassium phenoxide with CO2 at 200 °C gives an 80% yield of p-hydroxybenzoic acid, which is used in the form of the propyl and butyl esters as a preservative in cosmetics and pharmaceuticals. 

Because of the presence of water a preservative should be added to hydrogels, see Sect. 12.5.3. Suitable preservatives are sorbic acid, glycerol and propylene glycol. Methyl hydroxybenzoate or a combination of methyl and propyl... 

As p-hydroxybenzoic acid esters present a relatively high pKa value (approx. 8.5), their antimicrobial action is less dependent on the pH value of the type of food to be preserved. In this respect they are superior to the organic preservative acids. Unfavourably, as in the case of phenol, p-hydroxybenzoic acid esters may be linked to some extent to proteins, emulsifiers or other food components on account of their phenolic hydroxylic-group and thus be inactivated. The antimicrobial action of the p-hydroxybenzoic acid esters is proportional to the alkyl chain length. Thus the antimicrobial action of the methyl ester is some 3 to 4 times, that of the ethyl ester some 5 to 8 times, that of the propyl ester about 25 times as powerful as phenol (Thompson, 1994). However, superimposed on this effect may be the water solubility of the esters, which is inversely proportional to the alkyl chain length. Since the activity spectra of the individual p-hydroxybenzoic acid esters are different, the application of mixtures can be profitable. 

Applications. In many countries the methyl, ethyl and n-propyl esters of p-hydroxybenzoic acid, as well as their sodium salts, are permitted for preservation of some foods. The maximum permissible quantity is around 0.1%. In the USA methyl- and propyl-paraben are considered GRAS. The maximum permissible quantity is 0.1%. Their main field of use is not food preservation but the preservation of pharmaceutical and cosmetic fat emulsions. The usage of the butyl ester is not allowed in food applications. 

Ethyl 4-hydroxybenzoate is a highly effective preservative with moderately good solubility in water. The spectrum of effectiveness in demonstrated by the MIC in Table 81. As a food preservative ethyl 4-hydroxybenzoate is often used in combination with propyl 4-hydroxybenzoate (8.1.11.3.) thus it is possible in most cases to use smaller overall amounts of alkyl 4-hydroxybenzoate than would otherwise be necessary. The favourable properties of ethyl 4-hydroxy benzoate makes it also highly suitable for preserving cosmetics and pharmaceuticals most frequently mixtures of alkyl 4-hydroxybenzoates are used. 

Cladosporium sphaerospermum (Gomes et al. 2002). In addition, MIC values obtained from monoaromatic phenols (methyl beta-orsellinate and methyl and ethyl orsellinates) derived from various Icelandic lichen species were found equal or higher than usual preservatives (methyl- and propyl-p-hydroxybenzoates, o-... 

Food preservatives are used primarily to prevent or retard microbial growth. The most typical food preservatives are sorbic acid, benzoic acid, propionic acid, and methyl-, ethyl- and propyl-esters of p-hydroxybenzoic acid (PHB, parabens). 

The parabens are a class of 4-hydroxybenzoic acid esters (primarily methyl, ethyl, propyl, and butyl esters) that are used as biological preservatives in liquid and semisolid dosage forms.Another preservative often used is benzyl alcohol. Parabens and benzyl alcohol are compendial items. These materials are very stable... 

Figure 5.6 Scatchard plot for the interaction of preservatives with cetomacrogol solutions A, benzoic acid (r/Df x 10 " B, p-hydroxybenzoic acid (r/Df x 10" ). C, methyl p-hydroxybenzoate (r/Df x 10 ). D, propyl p-hydroxybenzoate (r/Df x 10 ). E, chlor-oxylenol (r/Df x 10" ). From Donbrow and Rhodes [43, 44] with permission.

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