Preservatives commonly used

Chlorocresol is a preservative commonly used in injections and its determination often involves the use of laborious extraction procedures in order to separate it from formulation components, followed by spectrophotometric measurement. A FIA method for chlorocresol was developed by utilising its reaction with nitrous acid to form a coloured nitro compound. The method was accurate to 99.5% of the true value of chlorocresol in a formulation and a precision of 1% was achieved. ... 

There are different kinds of chemical preservatives commonly used in foods which either inhibit the activity of bacteria or kill the bacteria. These chemicals include benzoates (such as sodium benzoate), nitrites (such as sodium nitrite), sulfites (such as sulfur dioxide) and sorbic acid. 

The methods of detecting and determining the preservatives commonly used in beer are as follows ... 

Application of phenyllactic acid (PLA) in the reduction of fungal mass in food is more desirable compared to other preservatives commonly used in bakery products, such as propionic acid and propionic salts. PLA concentrations effective against fungi from bakery products are usually lower than those required for inhibitory activity. Required concentrations have been reported as L. monocytogenes, 13 mg/ml S. aureus, E. coli, Aeromonas hydrophila, 20 mg/ml, whereas at pH 4 a concentration of < 7.5 mg/ml is enough to inhibit > 50% of bacterial growth (Lavermicocca, Valerio, and Visconti, 2003). 

Preservatives are often needed to prevent microbial and fungal growth in LDLDs. Preservatives commonly used are formaldehyde, gluteraldehyde, benzoic acid, Kathon , Dowicil , Bronopol , various esters of hydroxybenzoic acid, and others. 

A systematic survey of wood preservatives is shown in Table 14.14.1, including wood preservatives containing solvents. Solvents are normally found in wet systems of wood preservatives. Commonly used solvents are substances which are applied in connection with normally used binders (aldehyde resins, acrylates and polyurethanes). Water or the appropriate solvents are added to binders. 

Finally, proteins are reported to be potential inhibitors of numerous preservatives commonly used in cosmetics (130). The mechanisms involved are various and not fully understood the reactivity of amino groups and electrostatic interactions are both possible. 

Other toxic preservatives commonly used by museum personnel include formaldehyde phenol, thymol, o-phenyl, and copper and zinc naphthanates. 

Nitrates are found in fairly high concentrations in beets, spinach, kale, coUards, eggplant, celery, and lettuce. AdditionaHy, nitrates and nitrites are commonly used in the curing solutions of bacon, ham, and other cured meats. In cured meats, nitrates and nitrites control the growth of microorganisms, particularly Clostridium botulinum, and also serve as color preservatives. 

Linker-Scanning Mutagenesis. Using linker-scanning mutagenesis (24) small sequences of DNA are removed and replaced with a synthetic restriction fragment or linker. This technique is commonly used in analysis of promoters and other control sequences in DNA, while preserving the spatial relationship between the sequences. 

The activity of the sorbates at a higher pH is one distinct advantage over the two other most commonly used food preservatives, benzoic and propionic acids, because the upper pH limits for activity of these compounds are approximately pH 4.5 and 5.5, respectively. Although the effect of sorbates can be microbiocidal under certain conditions, activity is most often manifested as a microbial growth retardant. 

Since much of the wood in common use today for joinery, including external window frames and roof trusses, is redwood, such as Pinus sylvestris, preservative treatment is very necessary. However, whilst it is known that little corrosion of fasteners can take place in dry wood (<15 Vo moisture... 

Commonly used in biology as a tissue preservative, formaldehyde, CIDO, contains a carbon -oxygen double bond. Draw the line-bond structure of formaldehyde, and indicate the hybridization of the carbon atom. 

Isothiazolinones are a class of broad-spectrum biocides used as preservatives in many household and industrial products. They are used in cosmetics and shampoos as a biocide to kill fungi and bacteria. Unlike the preservatives DMDM hydantoin and imidazolidinyl urea, also commonly used in these products, isothiazolinones do not release formaldehyde, to which some people are sensitive. On the other hand, some people are sensitive to isothiazolinones. 

Another widespread application of cold storage of tissue for transplantation is that of preservation of the cornea. Inj uries leading to corneal scarring, various kinds of diseases, and the production of comeal opacity are leading causes of blindness. Cornea transplantation is a commonly used and highly successful procedure. It... 

Potassium sulfite is commonly used as a food preservative, because the sulfite anion undergoes reactions that release sulfur dioxide, an effective preservative. Determine the concentrations of the ionic species present in a solution of potassium sulfite that is 0.075 M. 

Examples of preservatives are phenylmercuric nitrate or acetate (0.002% w/v), chlorhexidine acetate (0.01 % w/v), thiomersal (0.01 % w/v) and benzalkorrium chloride (0.01 % w/v). Chlorocresol is too toxic to the comeal epithehum, but 8-hydroxyquinoline and thiomersal may be used in specific instances. The principal considerahon in relation to antimicrobial properties is the activity of the bactericide against Pseudomonas aeruginosa, a major source of serious nosocomial eye infections. Although benzal-konium chloride is probably the most active of the recommended preservatives, it cannot always be used because of its incompatibility with many compounds commonly used to treat eye diseases, nor should it be used to preserve eye-drops containing anaesthetics. Since benzalkonium chloride reacts with natural mbber, silicone or butyl rabber teats should be substituted. Since silicone mbber is permeable to water vapour, products should not be stored for more than 3 months after manufacture. As with all mbber components, the mbber teat should be pre-equilibrated with the preservative prior to... 

PCP is commonly used as a wood preservative having both antifungal and insecticide properties. It has also been used in a range of areas for antifungal, antibacterial, general herbicide, and slime prevention in both industrial and consumer applications. Chronic exposure to PCP has effects on the liver, kidneys, and immune system. PCP also has the potential to cause reproductive problems and has been listed as a probable carcinogen. 

A method of aspirating cells from the tumor via insertion of a small-bore needle into the lesion and aspirating. Commonly used to evaluate lymph nodes or other poorly accessible sites, it has the advantage of being faster and less invasive than other biopsy methods however, it does not preserve the architecture of the tumor and may return cells that are undergoing cell death, which negates histologic analysis. 

Phenolic biocides are still used extensively throughout the Figure 4 PCMC metalworking industry to preserve aqueous based metalworking fluids. One of the most commonly used phenolic biocides is p-chloro-m-cresol, (see PCMC, Figure 4). 

Some strains of P. aeruginosa are resistant to benzalkonium chloride and, in fact, can be grown in solutions concentrated in this agent. This has caused great concern because of the virulent nature of this organism in ocular infections, as discussed previously. Thus, it was an important finding in 1958 that the acquired resistance could be eliminated by the presence of ethylenediaminetetracetic acid (sodium edetate) in the formulation. This action of EDTA has been correlated with its ability to chelate divalent cations, and it is commonly used as a preservative aid [125]. The use of disodium EDTA, where compatible, is recommended in concentrations up to 0.1%. 

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