Selecting a Disinfectant

Healthcare facilities use a number of disinfectants, including alcohol, chlorine, chlorine compounds, hydrogen peroxide, phenolic substances, and quaternary ammonium compounds. Never 

Healthcare facilities use a number of disinfectants, including alcohol, chlorine, chlorine compounds, hydrogen peroxide, phenolic substances, and quaternary ammonium compounds. Never routinely interchange disinfectants. Proper selection and use of disinfectants provide the key to effective safety and quality control. Alcohols demonstrate variable effectiveness against some bacteria and fungi. Alcohols act fast, leave no residue, and can compatibly combine with other disinfectants such as quaternaries, phenolic substances, and iodine to form tinctures. Aldehydes can prove effective against a wide spectrum of bacteria and viruses, including spores, when used properly. They also 

---

The choice of a chemical disinfectant depends upon its efficiency against the particular microorganism being handled, and also upon its other physical characteristics. When selecting a disinfectant, the following factors must be considered ... 

Carefully disinfect the needle and syringe set (be careful in selecting a disinfectant—see Section 7.3.). The used disinfectant is handled as a liquid radioactive waste. 

Metaxylenol is an important intermediate for the manufacture of para chloro meta xylenol which is used a disinfectant. Meta xylenol may be produced by liquid phase or by vapour phase reaction. Metaxylenol is produced by sulphonation of xylene followed by hydrolysis in liquid phase but this yeilds many other by-products(l,2,3). However, catalytic conversion of isophorone yields meta xylenol selectively and the amounts of other by-products can be controlled (4,5,6). 

Although the terms are often used interchangeably, a disinfectant is a compound that is used to kill microorganisms in an inanimate environment, whereas an antiseptic is one that is used to inhibit bacterial growth both in vitro and in contact with the surfaces of living tissues. Disinfectants and antiseptics do not have selective toxicity, and their clinical use is therefore limited. Most antiseptics delay wound healing. 

H2O2 is one of essential chemicals for pulp breaching and waste treatment. H2O2 is expected to use as an oxidant for selective oxidation of hydrocarbons and a disinfectant for living environments. The industrial chemical process of H2O2 synthesis is limited to use of the anthraquinone method however, the production cost and transport... 

Chlorine dioxide is a selective oxidant and a powerful primary disinfectant. It does not combine with ammonia, like chlorine, so it is useful as a disinfectant when ammonia is present. The use of chlorine dioxide instead of chlorine results in fewer chlorinated by-products. And it does not form bromate like ozone. It does, however, produce chlorite as a reaction product, and this substance is regulated (maximum contaminant level [MCL] 1.0 mg/L). Therefore, the dosage of chlorine dioxide is controlled (maximum residual 0.8 mg/L), thus limiting producing chlorite from this source. 

Formaldehyde has been well known as a disinfectant and preservative from early times and was originally obtained in low yields from special lamps by burning wood alcohol. As further practical apphcations were introduced, larger quantities were supphed from the partial combustion or selective oxidation of methanol. 

Although certain variability in the quality of the WWTP effluent was found, regenerated wastewater by the selected process resulted of a good constant composition in the measured parameters, with important reduction of all the measured pollutants. Disinfection by UV achieved almost 100% of effectiveness in the destruction of microorganisms ( . coll). Conductivity, turbidity or TDS parameters... 

It is only very recently that organic componnds synthesized by humans have begun to exert a selection pressure upon natural populations, with the consequent emergence of resistant strains. Pesticides are a prime example and will be the principal subject of the present section. It should be mentioned, however, that other types of biocides (e.g., antibiotics and disinfectants) can produce a similar response in microbial populations that are exposed to them. 

Susceptibility of viruses to antimicrobial agents can depend on whether the viruses possess a lipid envelope. Non-lipid viruses are frequently more resistant to disinfectants and it is also likely that such viruses cannot be readily categorized with respect to their sensitivities to antimicrobial agents. These viruses are responsible for many nosocomial infections, e.g. rotaviruses, picornaviruses and adenoviruses (see Chapter 3), and it may be necessary to select an antiseptic or disinfectant to suit specific circumstances. Certain viruses, such as Ebola and Marburg which cause haemorrhagic fevers, are highly infectious and their safe destruction by disinfectants is of paramount importance. 

The intended application of an antimicrobial agent, whether for preservation, antisepsis or disinfection, will influence its selection and also affect its performance. For example, in medicinal preparations the ingredients in the formulation may antagonize preservative activity. The risk to the patient will depend on whether the antimicrobial is in close contact with a break in the skin or mucous membranes or is introduced into a sterile area of the body. 

The clinical relevance of biocide resistance of antibiotic-resistant staphylococci is, however, unclear. It has been claimed that the resistance of these organisms to cationic-type biocides confers a selective advantage, i.e. survival, when such disinfectants are employed clinically. However, the in-use concentrations are several times higher than those to which the organisms are resistant. 

Apart from a few applications, such as UV disinfection and lacquer hardening, the intensity of UV radiation is well below that of visible light in ambient daylight or indoor lighting. A UV sensor must therefore be insensitive to visible light, otherwise the detection signal would easily be drowned out by the visible fraction of the radiation spectrum. Sensors that fulfill this requirement have a selective spectral sensitivity in the UV range. There are two important selectivities, known as visible-blindness and solar-blindness. 

Sufficiently cheap UV photodiodes are available but they are not visible-blind. Filters have to be used, but they raise the costs. Sufficiently selective photodiodes are also available but they are too expensive, mainly due to their only recently established technology. The sensor costs have been a limiting factor in two application fields of UV sensors, namely water disinfection and combustion monitoring, on the industrial as well as on the household scale. 

---