Part of the induction course for students undertaking diploma and degree in Analytical Chemistry, Applied Biology, Medical Lab Sciences and Food Technology.

1. Prepare cleaning reagents and solutions.a.
Clean the laboratory.b.
Clean laboratory equipment and apparatus.c.
By the end of this sub-unit, the trainee should be able to do the following;
The Importance Of Keeping A Clean Laboratory
Keeping your laboratory clean is important. Here are six reasons why it is important to keep up
to date with your laboratory cleans!
Keep Your Work Area Tidy•
If your work area is unclean, it will be very difficult to keep it tidy and a neat work area is
very important for laboratory efficiency. How many times have you accidently double
ordered reagents, or ordered reagents when they were already available?
Keeping the work area tidy can also help towards improving the organizational elements of
your laboratory. However, a tidy laboratory must first be a clean laboratory.
It Can Help You To Prevent Inaccurate Results•
If your laboratory is unclean, it could affect results. Incorrectly cleaned glassware could
result in incorrect measurements which could result in incorrect results. These inaccuracies
could waste money or even result in false positive or false negative results.
Cleaning A Laboratory Can Help It Stay Organised•
Keeping your laboratory organized is very important. However, just like a tidy lab, an
organized lab must also be clean. Good organization and a tidy workplace are vital to
keeping the laboratory running at its most efficient; you can't have and organized and tidy
workspace without first having a clean workspace.
An Unclean Laboratory Can Be Dangerous•
Sometimes cleaning laboratory is just a matter of cleaning up dust or some spilled distilled
water, however sometimes a laboratory clean involves cleaning up hazardous chemicals or
potentially infectious bacteria. This is why trained professionals may be required and strict
health and safety protocol need to be put into place. Laboratories often work with various
materials that have the potential to be dangerous. As such, when accidents do occur, it can
be very beneficial to know how to manage an emergency spill.
It Can Help You To Save Money•
Keeping your workplace clean and tidy can help your business save money. When we think
of costs in laboratories, people often consider the cost of equipment or the energy costs to
run such equipment.
However, one thing that people do not consider with regards to cost is how much extra cost
is added when your workspace is untidy and unorganized. Searching for reagents wastes
time, and time wasted is not a valuable use of your time. Additionally an untidy workplace
could slow down your workflow, meaning that time is not being used in its most efficient
CLEANING IN THE LABORATORY
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2. could slow down your workflow, meaning that time is not being used in its most efficient
manner, which could slowly add costs.
Just like any other work space, keeping a laboratory tidy and organized can help to reduce
costs by increasing the efficiency of the workplace.
Comply With Health And Safety Regulations•
It is important that you keep your workplace in a manner that complies with health and
safety regulations. Laboratories have the potential to be very dangerous and as such, strict
health and safety policies are very important.
Importance of clean Laboratory Equipment & Apparatus
A wide range of different glass, ceramic or plastic vessels are used in laboratories to
- perform experiments and analyses,
- to culture tissue,
- take specimens and many other applications.
Ensuring that standards of apparatus cleanliness do not jeopardize the outcome of experiments is
of paramount importance in laboratories and requires complex treatment processes and excellent
efficiency.
Good laboratory practice demands clean glassware, because the most carefully executed piece of
work may give a flawed result if dirty glassware is used. In all instances glassware must be
- physically clean,
- it must be chemically clean,
- must be microbiologically clean or sterile.
Even the most carefully executed experiment can give erroneous results if dirty glassware is
bought to use. If the glassware that is used for measuring liquids is contaminated with grease and
other materials, it prevents the glass from being uniformly wetted. This in turn will affect the
volume of liquid delivered and the amount of residue adhering to the walls of the container.
Likewise, presence of impurities in glass lab ware can distort the meniscus and can prevent one
from getting the correct results out of the experiment.
To keep your glass lab ware neat and clean, you must wash it immediately after use. Put
glassware in water if you cannot clean it immediately otherwise the residue will stick to the
lab ware and it would get difficult to remove it.
-
Keeping the laboratory glassware physically neat and clean, free of grease, and bacteria is
therefore of the utmost importance.
For washing the glass lab ware, make use of appropriate soap, detergent, or cleaning
powder. Try to use soap and cleaning powder without any abrasives as it can scratch the
glass. However, for glassware that is too dirty, you can make use of cleaning powder with
mild abrasive action to get good cleaning results. Chromic acid solution is quite effective in
cleaning unduly clouded or dirty glassware. For scrubbing the glassware thoroughly, you
must use a brush.
-
After cleaning, rinse the glassware with tap water. Allow the water to run into and over the
glassware and then fill each piece with water. Fill test tubes, flasks, and other glassware
with water and shake and empty them. Do this for at least 5-6 times to clean the glassware
properly. For cleaning contaminated glassware, you will have to sterilize them too.
-
Washed lab ware must either be placed in a basket with their mouth downwards for-
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3. Washed lab ware must either be placed in a basket with their mouth downwards for
allowing them to dry completely or they should be made to dry in an oven. You can also
hang test tubes, flasks, and other lab ware on wooden pegs for drying them out. Stand dry
cylinders, burets, and pipets on a towel for drying them properly.
-
Place clean glassware in a cabinet to protect it from dust. You can also make use of cotton,
or cork, or can tape a piece of paper on the mouth of the glassware to prevent dirt and dust
from entering the glassware. Keep washed, cleaned, and sterilized glassware pieces in
special racks and at a distance to avoid any breakage.
-
With proper care and maintenance you can not only increase the life of your lab ware, but can
also enhance your lab safety.
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4. Cleaning laboratory glassware is important because contaminated or dirty glassware can lead to
inaccurate results in the lab.
A good way to confirm that your glassware is clean is to make sure that distilled water uniformly
wets the surface, according to Corning. This tells you that the surface is free of grease and other
contaminants that could alter the volume being measured or introduce impurities into the liquid.
What Is the Proper Procedure for Cleaning Laboratory Glassware?
One basic procedure is to start with the gentlest methods, scraping off any solids and then using
brushes and normal soaps and detergents. If this doesn't get the job done, move on to longer
soaks and harsher cleaners. Finally, when the glassware is fully clean, rinse it thoroughly and
allow it to dry.
Here are some ideas and pointers that will help with each stage of this process:
Clean It as Soon as You Can1.
Wash glassware in hot water or a glassware washer as soon as you're finished using it to avoid
the formation of hard-to-remove residue. Corning recommends soaking glassware in water if it's
impossible to wash it immediately after use.
Use the Right Brush2.
Scrub all parts of the glassware thoroughly with laboratory glassware cleaning brushes. Make
sure you have a variety of brush sizes on hand suitable for cleaning laboratory glassware of all
kinds, including test tubes, funnels, flasks and bottles. Corning suggests choosing a brush with a
wooden or plastic handle instead of a metal handle, to help protect glassware from accidental
scratches or abrasions. An overly worn brush can also cause accidental scratches if its bristles no
longer prevent the spine of the brush from hitting the glass.
Don’t Forget the Cleaner3.
When washing laboratory glassware, many soaps, detergents and cleaning powders can be used.
According to Corning, cleaning agents with mild abrasive action will give better results on very
dirty glassware, as long as the abrasive doesn't scratch the glass.
Try Giving it a Soak4.
If basic cleaners don't get the job done, or if there's material in places where brushes can't reach,
a next step is to try a long soak in a gentle solvent, according to the University of Wisconsin
Office of Chemical Safety. The efficacy can be enhanced with heat soaking or mild agitation.
If All Else Fails, Get Aggressive5.
Occasionally, more aggressive cleaning solutions may be necessary when laboratory glassware is
extremely dirty. These solutions are often highly corrosive, involving concentrated acids or
bases, and can cause injury.
Sterilize Before Cleaning When Necessary6.
Some glassware should be sterilized before cleaning, according to life sciences manufacturer
Millipore Sigma. This includes glassware contaminated with blood clots and glassware on which
viruses or spore-bearing bacteria are present. Glassware can be sterilized in autoclaves, steam
ovens or by boiling for 30 minutes with in water with 1% to 2% soft soap or detergent.
Rinse All Glassware7.
Detergent or cleaning fluid residue can contaminate your work the next time you use the
How to Clean Laboratory Glassware
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5. Detergent or cleaning fluid residue can contaminate your work the next time you use the
glassware. Corning recommends this procedure for rinsing:
First, rinse glassware very thoroughly with running tap water, filling, shaking and emptying
it at least six times. Run very hard water through a deionizer or reverse osmosis system
before using.
-
Then, rinse all glassware in a large bath of distilled or high purity water.-
Finally, rinse each piece individually in high purity water.-
Dry It, Too8.
Laboratory glassware can be air dried. Corning recommends hanging glassware from wooden
pegs or placing in baskets facing downward, with a clean cloth at the bottom to keep the mouths
of the vessels clean. Glassware can also be oven dried at temperatures lower than 140° C, though
glassware used for volumetric measurements should be dried at temperatures of no more than
80° C to 90° C.
Q: Which Acid Is Used for Cleaning Glassware in the Laboratory?
A: Acid solutions including aqua regia (a mixture of nitric acid and hydrochloric acid), diluted
sulfuric acid, chromic acid solution, piranha solution and fuming sulfuric acid are used to clean
laboratory glassware, according to the University of Wisconsin Office of Chemical Safety.
These are potentially hazardous substances and should be used only by people who have been
trained in their proper use and are fully equipped with the appropriate personal protective
equipment (PPE). Corning recommends heavy duty slip-resistant and chemically resistant
gloves, eye protection, lab coats and aprons, and states that the work should be done in a fume
hood when appropriate.
Q: Why is Acetone Used for Cleaning Glassware?
A: Acetone is a fat solvent that can help remove grease from laboratory glassware, according to
Corning and the University of Wisconsin Office of Chemical Safety. However, according to
Corning, the best way to remove grease is boiling glassware in a weak solution of sodium
carbonate.
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6. Alcohol
Overview.
In the healthcare setting, “alcohol” refers to two water-soluble chemical compounds—ethyl alcohol and
isopropyl alcohol—that have generally underrated germicidal characteristics. These alcohols are rapidly
bactericidal rather than bacteriostatic against vegetative forms of bacteria; they also are tuberculocidal,
fungicidal, and virucidal but do not destroy bacterial spores. Their cidal activity drops sharply when diluted
below 50% concentration, and the optimum bactericidal concentration is 60%–90% solutions in water.
Mode of Action.
The most feasible explanation for the antimicrobial action of alcohol is denaturation of proteins. This
mechanism is supported by the observation that absolute ethyl alcohol, a dehydrating agent, is less bactericidal
than mixtures of alcohol and water because proteins are denatured more quickly in the presence of water .
Protein denaturation also is consistent with observations that alcohol destroys the dehydrogenases of
Escherichia coli, and that ethyl alcohol increases the lag phase of Enterobacter aerogenes and that the lag phase
effect could be reversed by adding certain amino acids. The bacteriostatic action was believed caused by
inhibition of the production of metabolites essential for rapid cell division.
Microbicidal Activity.
Methyl alcohol (methanol) has the weakest bactericidal action of the alcohols and thus seldom is used in
healthcare.
The bactericidal activity of various concentrations of ethyl alcohol (ethanol) was examined against a variety of
microorganisms in exposure periods ranging from 10 seconds to 1 hour. Pseudomonas aeruginosa was killed in
10 seconds by all concentrations of ethanol from 30% to 100% (v/v), and Serratia marcescens, E, coli and
Salmonella typhi were killed in 10 seconds by all concentrations of ethanol from 40% to 100%. The gram-
positive organisms Staphylococcus aureus and Streptococcus pyogenes were slightly more resistant, being
killed in 10 seconds by ethyl alcohol concentrations of 60%–95%. Isopropyl alcohol (isopropanol) was slightly
more bactericidal than ethyl alcohol for E. coli and S. aureus.
Ethyl alcohol, at concentrations of 60%–80%, is a potent virucidal agent inactivating all of the lipophilic viruses
(e.g., herpes, vaccinia, and influenza virus) and many hydrophilic viruses (e.g., adenovirus, enterovirus,
rhinovirus, and rotaviruses but not hepatitis A virus (HAV) or poliovirus). Isopropyl alcohol is not active
against the non-lipid enteroviruses but is fully active against the lipid viruses. Studies also have demonstrated
the ability of ethyl and isopropyl alcohol to inactivate the hepatitis B virus(HBV) and the herpes virus, and ethyl
alcohol to inactivate human immunodeficiency virus (HIV) 227, rotavirus, echovirus, and arbovirus.
In tests of the effect of ethyl alcohol against M. tuberculosis, 95% ethanol killed the tubercle bacilli in sputum
or water suspension within 15 seconds. In 1964, Spaulding stated that alcohols were the germicide of choice for
tuberculocidal activity, and they should be the standard by which all other tuberculocidals are compared.
Ethyl alcohol (70%) was the most effective concentration for killing the tissue phase of Cryptococcus
neoformans, Blastomyces dermatitidis, Coccidioides immitis, and Histoplasma capsulatum and the culture
phases of the latter three organisms aerosolized onto various surfaces. The culture phase was more resistant to
the action of ethyl alcohol and required about 20 minutes to disinfect the contaminated surface, compared with
<1 minute for the tissue phase.
Isopropyl alcohol (20%) is effective in killing the cysts of Acanthamoeba culbertsoni as are chlorhexidine,
hydrogen peroxide, and thimerosal .
Uses.
It is used to sterilize working benches and biosafety chambers that largely are used in the processing of
specimens and samples.
Alcohols are not recommended for sterilizing medical and surgical materials principally because they lack
sporicidal action and they cannot penetrate protein-rich materials.
The documented shortcomings of alcohols on equipment are that they damage the shellac mountings of lensed
instruments, tend to swell and harden rubber and certain plastic tubing after prolonged and repeated use, bleach
rubber and plastic tiles
Alcohols are flammable and consequently must be stored in a cool, well-ventilated area. They also evaporate
rapidly, making extended exposure time difficult to achieve unless the items are immersed.
Chlorine and Chlorine Compounds
Overview.
Hypochlorites, the most widely used of the chlorine disinfectants, are available as liquid (e.g.,sodium
hypochlorite) or solid (e.g., calcium hypochlorite). The most prevalent chlorine products are aqueous solutions
of 5.25%–6.15% sodium hypochlorite, usually called household bleach.
They have a…….
- broad spectrum of antimicrobial activity,
- do not leave toxic residues,
- are unaffected by water hardness,
- are inexpensive and fast acting,
- remove dried or fixed organisms and biofilms from surfaces,
- and have a low incidence of serious toxicity.
Sodium hypochlorite at the concentration used in household bleach (5.25-6.15%)
- can produce ocular irritation or oropharyngeal, esophageal, and gastric burns. Other disadvantages of
hypochlorites include
- corrosiveness to metals in high concentrations (>500 ppm),
- inactivation by organic matter,
- discoloring or “bleaching” of fabrics,
- release of toxic chlorine gas when mixed with ammonia or acid (e.g., household cleaning agents)
Mode of Action.
The exact mechanism by which free chlorine destroys microorganisms has not been elucidated.
Inactivation by chlorine can result from a number of factors:
- oxidation of sulfhydryl enzymes and amino acids;
- ring chlorination of amino acids;
- loss of intracellular contents;
- decreased uptake of nutrients;
- inhibition of protein synthesis;
- decreased oxygen uptake;
- oxidation of respiratory components;
- decreased adenosine triphosphate production;
- breaks in DNA and depressed DNA synthesis.
The actual microbicidal mechanism of chlorine might involve a combination of these factors or the effect of
chlorine on critical sites.
Microbicidal Activity
It is bactericidal, fungicidal, sporicidal, tuberculocidal, and virucidal.
Low concentrations of free available chlorine have a biocidal effect on mycoplasma and vegetative bacteria (<5
ppm) in seconds in the absence of an organic load.
Higher concentrations (1,000 ppm) of chlorine are required to kill M. tuberculosis.
A concentration of 100 ppm will kill ≥99.9% of B. atrophaeus spores within 5 minutes and destroy mycotic
agents in <1 hour. Acidified bleach and regular bleach (5,000 ppm chlorine) can inactivate Clostridium difficile
spores in ≤10 minutes.
One study reported that 25 different viruses were inactivated in 10 minutes with 200 ppm available chlorine.
Several studies have demonstrated the effectiveness of diluted sodium hypochlorite and other disinfectants to
inactivate HIV. Chlorine (500 ppm) showed inhibition of Candida after 30 seconds of exposure. In experiments
using the AOAC Use-Dilution Method, 100 ppm of free chlorine killed 106–107 S. aureus, Salmonella
choleraesuis, and P. aeruginosa in <10 minutes.
Because household bleach contains 5.25%–6.15% sodium hypochlorite, or 52,500–61,500 ppm available
chlorine, a 1:1,000 dilution provides about 53–62 ppm available chlorine, and a 1:10 dilution of household
bleach provides about 5250–6150 ppm.
Uses.
A 1:10–1:100 dilution of 5.25%–6.15% sodium hypochlorite (i.e., household bleach) has been recommended
for decontaminating blood spills.Click this link to read on how to make dilutions of hypochlorite
https://www.who.int/docs/default-source/wpro---documents/wpro---pdf-infographics/covid-19/bleach-dilution-
and-guidance-for-visitors-20200622.pdf?sfvrsn=4fcf7133_2
Other uses in healthcare include as a disinfectant for manikins, laundry, dental appliances, hydrotherapy tanks,
regulated medical waste before disposal, and the water distribution system in hemodialysis centers and
hemodialysis machines.
Formaldehyde
Overview.
Formaldehyde is used as a disinfectant and sterilant in both its liquid and gaseous states.
Formaldehyde is sold and used principally as a water-based solution called formalin, which is 37%
formaldehyde by weight.
The aqueous solution is a bactericide, tuberculocide, fungicide, virucide and sporicide. OSHA indicated that
formaldehyde should be handled in the workplace as a potential carcinogen and set an employee exposure
Chemical Disinfectants used in Cleaning the Lab
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7. formaldehyde should be handled in the workplace as a potential carcinogen and set an employee exposure
standard for formaldehyde that limits an 8-hour time-weighted average exposure concentration of 0.75 ppm
Ingestion of formaldehyde can be fatal, and long-term exposure to low levels in the air or on the skin can cause
asthma-like respiratory problems and skin irritation, such as dermatitis and itching. For these reasons,
employees should have limited direct contact with formaldehyde, and these considerations limit its role in
sterilization and disinfection processes.
Mode of Action.
Formaldehyde inactivates microorganisms by alkylating the amino and sulfhydryl groups of proteins and ring
nitrogen atoms of purine bases of microorganisms, which alters RNA, DNA, and protein synthesis.
Microbicidal Activity.
Varying concentrations of aqueous formaldehyde solutions destroy a wide range of microorganisms.
Inactivation of poliovirus in 10 minutes required an 8% concentration of formalin, but all other viruses tested
were inactivated with 2% formalin.
2% formaldehyde is a tuberculocidal agent, inactivating M. tuberculosis in 2 minutes, and 2.5% formaldehyde
inactivated about Salmonella Typhi in 10 minutes in the presence of organic matter.
The sporicidal action of formaldehyde was slower than that of glutaraldehyde in comparative tests with 4%
aqueous formaldehyde and 2% glutaraldehyde against the spores of B. anthracis. The formaldehyde solution
required 2 hours of contact to achieve an inactivation factor of 104, whereas glutaraldehyde required only 15
minutes.
Uses.
Although formaldehyde-alcohol is a chemical sterilant and formaldehyde is a high-level disinfectant, the uses of
formaldehyde are limited by its irritating fumes and its pungent odor even at very low levels (<1 ppm). For
these reasons and others—such as its role as a suspected human carcinogen linked to nasal cancer and lung
cancer, this germicide is excluded from routine lab disinfection.
Formaldehyde is used in the health-care setting to prepare viral vaccines (e.g., poliovirus and influenza); as an
embalming agent; and to preserve anatomic specimens; and historically has been used to sterilize surgical
instruments, especially when mixed with ethanol.
Paraformaldehyde, a solid polymer of formaldehyde, can be vaporized by heat for the gaseous decontamination
of laminar flow biologic safety cabinets when maintenance work or filter changes require access to the sealed
portion of the cabinet.
Glutaraldehyde
Overview.
Glutaraldehyde is a saturated dialdehyde that has gained wide acceptance as a high-level disinfectant and
chemical sterilant.
Aqueous solutions of glutaraldehyde are acidic and generally in this state are not sporicidal. Only when the
solution is “activated” (made alkaline) by use of alkalinating agents to pH 7.5–8.5 does the solution become
sporicidal. Once activated, these solutions have a shelf-life of minimally 14 days because of the polymerization
of the glutaraldehyde molecules at alkaline pH levels. This polymerization blocks the active sites (aldehyde
groups) of the glutaraldehyde molecules that are responsible for its biocidal activity.
The use of glutaraldehyde-based solutions in health-care facilities is widespread because of their advantages,
including
- excellent biocidal properties;
- activity in the presence of organic matter (20% bovine serum);
- and noncorrosive action to endoscopic equipment, thermometers, rubber, or plastic equipment
Mode of Action.
The biocidal activity of glutaraldehyde results from its alkylation of sulfhydryl, hydroxyl, carboxyl, and amino
groups of microorganisms, which alters RNA, DNA, and protein synthesis,just like Formaldehyde.
Microbicidal Activity.
The in vitro inactivation of microorganisms by glutaraldehyde has been extensively investigated and reviewed.
Several investigators showed that ≥2% aqueous solutions of glutaraldehyde, buffered to pH 7.5–8.5 with
sodium bicarbonate effectively killed vegetative bacteria in <2 minutes; M. tuberculosis, fungi, and viruses in
<10 minutes; and spores of Bacillus and Clostridium species in 3 hours. Spores of C. difficile are more rapidly
killed by 2% glutaraldehyde than are spores of other species of Clostridium and Bacillus.
Microorganisms with substantial resistance to glutaraldehyde have been reported, including some mycobacteria
(M. chelonae, Mycobacterium avium-intracellulare, M. xenopi), Methylobacterium mesophilicum,
Trichosporon, fungal ascospores (e.g., Microascus cinereus, Cheatomium globosum), and Cryptosporidium.
Uses.
Glutaraldehyde is noncorrosive to metal and does not damage lensed instruments, rubber or plastics.
Glutaraldehyde should not be used for cleaning noncritical surfaces because it is too toxic and expensive.
Acute or chronic exposure can result in skin irritation or dermatitis, mucous membrane irritation (eye, nose,
mouth), or pulmonary symptoms. Epistaxis, allergic contact dermatitis, asthma, and rhinitis also have been
reported in workers exposed to glutaraldehyde.
Hydrogen Peroxide
Overview.
It is bactericidal, virucidal, sporicidal, and fungicidal properties .It is a liquid chemical sterilant and high-level
disinfectant.
Mode of Action.
Hydrogen peroxide works by producing destructive hydroxyl free radicals that can attack membrane lipids,
DNA, and other essential cell components.
Microbicidal Activity.
Hydrogen peroxide is active against a wide range of microorganisms, including bacteria, yeasts, fungi, viruses,
and spores.
A 0.5% accelerated hydrogen peroxide demonstrated bactericidal and virucidal activity in 1 minute and
mycobactericidal and fungicidal activity in 5 minutes
In an investigation of 3%, 10%, and 15% hydrogen peroxide for reducing spacecraft bacterial populations, a
complete kill of spores (i.e., Bacillus species) occurred with a 10% concentration and a 60-minute exposure
time. A 3% concentration for 150 minutes killed 106 spores in six of seven exposure trials. A 10% hydrogen
peroxide solution resulted in a 103 decrease in B. atrophaeus spores, and a ≥105 decrease when tested against
13 other pathogens in 30 minutes at 20°C
Other studies demonstrated the antiviral activity of hydrogen peroxide against rhinovirus. The time required for
inactivating three serotypes of rhinovirus using a 3% hydrogen peroxide solution was 6–8 minutes; this time
increased with decreasing concentrations (18-20 minutes at 1.5%, 50–60 minutes at 0.75%).
Under normal conditions, hydrogen peroxide is extremely stable when properly stored (e.g., in dark containers).
The decomposition or loss of potency in small containers is less than 2% per year at ambient temperatures.
Uses.
Commercially available 3% hydrogen peroxide is a stable and effective disinfectant when used on inanimate
surfaces.
Phenolic/Phenols
e.g. Lysol
Overview.
Phenol has occupied a prominent place in the field of hospital disinfection since its initial use as a germicide by
Lister in his pioneering work on antiseptic surgery. Phenol derivatives originate when a functional group (e.g.,
alkyl, phenyl, benzyl, halogen) replaces one of the hydrogen atoms on the aromatic ring.
Two phenol derivatives commonly found as constituents of hospital disinfectants are ortho-phenylphenol and
ortho-benzyl-para-chlorophenol. The antimicrobial properties of these compounds and many other phenol
derivatives are much improved over those of the parent chemical. Phenolics are absorbed by porous materials,
and the residual disinfectant can irritate tissue.
Mode of Action.
In high concentrations, phenol acts as a gross protoplasmic poison, penetrating and disrupting the cell wall and
precipitating the cell proteins. Low concentrations of phenol and higher molecular-weight phenol derivatives
cause bacterial death by inactivation of essential enzyme systems and leakage of essential metabolites from the
cell wall .
Microbicidal Activity.
Published reports on the antimicrobial efficacy of commonly used Phenolics showed they were bactericidal,
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8. 5% phenol was lethal for viruses-
a 2% solution of a phenolic (15% ortho-phenylphenol and 6.3% para-tertiary-amylphenol) inactivated all
but one of 11 fungi tested
-
Published reports on the antimicrobial efficacy of commonly used Phenolics showed they were bactericidal,
fungicidal, virucidal, and tuberculocidal .commercial Phenolics are not sporicidal
Uses.
Many phenolic germicides are registered as disinfectants for use on environmental surfaces (e.g., bedside tables,
bedrails, and laboratory surfaces) and noncritical medical devices.
Read and make notes on quaternary ammonium and iodine-based disinfectants, click this
link to read more ….
-
https://www.cdc.gov/infectioncontrol/guidelines/disinfection/disinfection-
methods/chemical.html#Phenolics
ASSINGMENT
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