Quaternary ammonium compounds QACs

In disinfection of instruments, the chemicals used must not adversely affect the instruments, e.g. cause corrosion of metals, affect clarity or integrity of lenses, or change texture of synthetic polymers. Many materials such as fabrics, rubber, plastics are capable of adsorbing certain disinfectants, e.g. quaternary ammonium compounds (QACs), are adsorbed by fabrics, while phenolics are adsorbed by rubber, the consequence ofthis being a reduction in concentration of active compound. A disinfectant can only exert its effect ifit is in contact with the item being treated. Therefore access to all parts of an instrument or piece of equipment is essential. For small items, total immersion in the disinfectant must also be ensured. 

Fig. 10.8 Quaternary ammonium compounds (QACs) A, general structure ofQACs B, benzalkonium chloride (n - S - 18) C, cetrimide (n - 12 - 14 or 16) D, cetylpyridinium chloride.

Quaternary ammonium compounds (QACs Chapter 10) such as cetrimide, and also the bisbiguanide, chlorhexidine, are notoriously prone to promote clumping. A non-ionic surface-active agent of the type formed by condensing ethylene oxide with a long-chain fatty acid such as Cirrasol ALN-WF (ICI Ltd), formerly known as Lubrol W, together with lecithin, added to the diluting fluid has been used to overcome this effect. 

Chemical disinfectants are limited in their use as air sterilants because of their irritant properties when sprayed. However, some success has been achieved with atomized propylene glycol at a concentration of 0.05-0.5 mgH and quaternary ammonium compounds (QACs) at 0.075% m be used. For areas which can be effectively sealed off for fumigation purposes, formaldehyde gas at a concentration of 1-2 mg H of air at a relative humidity of 80-90% is effective. 

Cationic surfactants Quaternary ammonium compounds (QACs)h ... 

Lecithin Quaternary Ammonium Compounds (QACs), Parabens, 6/s-biguanides Bacteria... 

Both spheroplasts and protoplasts are equally sensitive to lysis by membrane-active agents such as quaternary ammonium compounds (QACs), phenols and chlorhexidine. This demonstrates that the difference in sensitivities of whole cells to these agents is not due to a difference in sensitivity of the target cytoplasmic membrane but in the different permeability properties of the overlying wall or envelope structures. 

Pig farmers have a higher incidence of asthma than the general population. Quaternary ammonium compounds (QACs) are commonly used disinfectants with no known sensitization effects. In a study of Dutch pig farmers, however, it was found that the incidence of asthmatic sensitization was much higher for those who used QACs than for those who did not use these disinfectants. I56l... 

This chapter presents neutralization procedures for six topical antimicrobial compounds [9] chlorhexidine gluconate (CHG), iodine (tinctures and povidone-iodine), alcohols (ethyl and isopropyl), triclosan, parachlorometaxylenol (PCMX), and quaternary ammonium compounds (QAC). 

These residues from cleaning agents and other fluids containing surfactants (e.g., cetyl pyridinium chloride and cetyl trimethyl ammonium bromide) may have bacteriostatic effects or cause flavor taints. To determine quaternary ammonium compounds (QACs), they are first extracted into solvent (1,1,2,2-tetrachlor-ethane) and then detected by the formation of a pink color with dioctyl sodium sulfosuccinate (Aerosol T), which is quantified by spectrophotometry. 

Quaternary ammonium compounds QACs, such as bcnzalkonium cUaide, are effective as sanitiza-s or disinfectants on a wide range of bacteria and some viruses. QAC solutions when combined with alcdiols can prove carosive when concentrated and users should wear goggles and gloves. 

The antimicrobial efficacy of the amine-formaldehyde reaction products essentially corresponds to the formaldehyde content of these compounds. Known exceptions are HTA, hexahydro-oxadiazines and octahydro-s-tetrazines, which derive from ammonia respectively certain alkylolhydrazines (Paulus, 1980) here the detection of formaldehyde by the Taimenbaum methods gives a negative result, which means that these substances have no significant antimicrobial effect at neutral to alkaline pH they release formaldehyde in acidic media only. This pH dependency is broken off, if, for example, HTA is quatemized (Jacobs et al., 1916). In contrast to HTA the quaternary hexaminium salts release formaldehyde widely independent of pH and therefore may be used as preservatives also for media of neutral to alkaline pH. They are not comparable with the surface active conventional quaternary ammonium compounds (QACs see Section 16.1)... 

Surface-active microbicides with cationic properties include not only the widely used quaternary ammonium compounds (QACs) but also long-chain (C12-C15) aliphatic alkyl amines, aliphatic diamines, guanidines and higua-... 

Long-chain quaternary ammonium compounds (QACs) are cationic surface active agents according to the general formula... 

A quaternary ammonium compound (QAC) for internal application in polymers and elastomers with some thermal stability limitations. 

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