Disinfectants

Protective Equipment and Disinfection solutions:

Equipment and disinfectant must be maintained near all areas where biohazardous materials are handled or stored and must be readily available at all times. A working solution (if appropriate) should be prepared regularly and dated. Discard expired solutions on a regular basis. Sufficient volumes (~4L) should be available to deal with the volumes of potential spills in the area and should be appropriate for the nature of the organism involved. Stock solutions should be available in addition to the working concentrations.

Personal Protective Equipment
there should be enough for at least two workers (never work alone doing a cleanup) and should include:
  • lab coat or coveralls
  • rubber/plastic apron
  • rubber boots
  • heavy rubber gloves (gauntlets preferred over latex examination gloves)
  • particle mask
  • HEPA filter mask if infection via respiratory route is possible
  • eye goggles (not just safety glasses)
Chemical disinfectant stock/working solution
(marked with date received and expiry date)
  • dilution containers
  • dilution instructions
  • paper towels (or similar adsorbent material)
  • mop and pail
  • squeegee
  • tongs (for broken glass recovery)
  • autoclave bags (6)

Some Characteristics of Chemical Disinfectants
Information adapted from "Concepts in Biosafety; Office of Environmental Health & Safety, University of Alberta (revised 1998)"

Definitions:

Stock solution refers to the concentrated form as received from the supplier. Sometimes different concentrations are available so be sure to indicate this. Mark the date received on the container.

Work solution: the concentration of solution prepared from the stock by diluting it with some solvent; specify solvent (water, alcohol, etc) and details of proportions to be mixed. Mark the date prepared on the container if the Work solution is stable for a time after preparation.

Active ingredient concentration: some working solutions are described in terms of the concentration of active agent in the working solution. If the stock solution is not 100% active ingredient, then you must calculate the concentration of active ingredient in the stock to get the correct concentration in the final working solution.

Expressing Concentration:
v = volume, (v/v is ml/100 ml)
w = weight, (w/v is g/100ml)

Example: household bleach is 5% (w/v) sodium hypochlorite. If you want 0.5% hypochlorite in the working solution, then dilute 100 ml of bleach with 900 ml water to get a 10% (v/v) solution of the original stock concentration. If you had a 12% bleach stock, then would mix 42 ml of bleach stock with 958 ml water (this is a 4.2% (v/v) solution of the original stock. Note: Double check manufacturer's dilution recommendations for all solutions as some of the following concentrations are based on reports from other publications. They may be wrong or the manufacturer may have altered their formulation.

Category: Quaternary ammonium detergent
Trade Name: Roccal™, OstroSan™
Working Concentration: 0.4 - 0.8% (v/v)
Mixing: 4 - 8 ml stock / liter water
Contact Time (min): 30
Notes - quaternary ammonium compounds:
  • solution is bacteriocidal, fungicidal and virucidal (on lipophilic viruses only)
  • NOT effective against tuberculosis or bacterial spores
  • concentrated stocks very injurious to eye; wear eye protection when diluting
Category: alcohol
Trade Name: ethanol or isopropanol
Working Concentration: 70% (v/v)
Mixing: 700 ml alcohol + 300 ml of water
Contact Time (min): 30

Notes - 70% alcohol:

  • no residue, not corrosive
  • is slow acting, may evaporate from surface before disinfection is complete
  • is flammable
  • effective on vegetative bacteria and lipid viruses; less effective on non-lipid viruses;
  • NOT effective on bacterial spores
Category: Bleach (household)
Trade Name: Chlorox™, Javex™ (5.25% hypochlorite)
Working Concentration: 0.5% (w/v) hypochlorite for routine use or 3.0 % (v/v) hypochlorite for bacterial spores
Mixing: 100 ml stock + 900 ml water or
600 ml stock + 400 ml water (spores)
Contact Time (min): 30

Notes - bleach

  • household bleach is about 5% (w/v) sodium hypochlorite; can get a 12% stock so should adjust your dilution to get the appropriate working concentration.
  • a strong oxidizer; avoid mixing with other chemicals
  • produces free chlorine in solution, is corrosive on metals. Wash area with soap/water after bleach has been removed
  • working solutions must be made fresh (daily); diluted stock quickly loses it's activity
  • unopened stock bottle probably good for 6 months. Label date received and expiry date
  • very effective disinfectant against many biohazards: bacteria (vegetativeand spores), lipid and non-lipid viruses
  • need high concentrations to kill tuberculosis bacteria and bacterial spores (use a 60% (v/v) solution of household bleach)
  • chlorine binds to proteins so if have a lot of protein in your samples (e.g. blood or cells grown in fetal calf serum), may need to use a higher concentration than 10% (v/v)
  • should not autoclave bleach solution as chlorine gas may be released from the autoclave.
  • also available in tablet form called Presept™, dissolve in water and use
Category: Iodine
Trade Name: Wescodyne™
Working Concentration: 0.45% iodine in solution or 2.5% (w/v) for bacterial spores
Mixing: 4.5 ml / liter water or 25 ml stock + 975 ml of 50% (v/v) ethanol in water (for spores)
Contact Time (min): 30

Notes - iodine

  • similar biocidal activity as chlorine
  • not as corrosive as chlorine
Category: phenolics
Trade Name: Dettol ™ , Lysol™ (5-7% phenols)
Working Concentration: 0.1-0.3% (w/v) of active ingredient
Mixing: 10 - 50 ml stock / liter water
Contact Time (min): 30

Notes - phenolics

  • compounds are derivatives of phenol
  • effective against some lipid viruses, ricekettsia, fungi, vegetative bacteria and tuberculosis
  • NOT effective against bacterial spores and non-lipid viruse
  • unpleasant odor, leaves sticky residue
  • concentrated stocks very injurious to eye; wear eye protection when diluting
Category: chemical cocktail
Trade Name: Super-Phen Plus™
Working Concentration: 0.63% (v/v)
Mixing: check manufacturer's recommendation
Contact Time (min): 30

Notes - Super-Phen Plus™

  • broad spectrum chemical mixture
  • effective on most biohazards including tuberculosis and bacterial spores
  • could be a good choice for a spill cleanup disinfectant because it is broadly effective
Category: glutaraldehyde
Trade Name: Cidex™
Working Concentration: 2% (w/v) glutaraldehyde in water
Mixing: check manufacturer's recommendation
Contact Time (min): 30

Notes - glutaraldehyde :

  • kills bacteria (vegetative and spores) and viruses ( lipid and non-lipid)
  • solution is irritating to nose, eyes and skin
  • can cause skin sensitization, liver damage and has a low exposure limit to people
  • less toxic than formaldehyde
  • a glutaraldehyde solution is stable for a long time but is not microcidal until the solution is 'activated' by adjusting the pH to ~7.7 with sodium bicarbonate.
  • after activated, the solution is useful for 7 - 18 days depending on the formulation
Category: formaldehyde
Trade Name: formalin (37% formaldehyde (w/v) in water)
Working Concentration: 0.2 - 8% formaldehyde in water
Mixing: 5 - 220 ml of 37% stock / liter of water
Contact Time (min): 30

Notes - formaldehyde :

  • effective biocidal agent but difficult to handle
  • very toxic, a carcinogen, a respiratory irritant
  • formaldehyde is a gas; usually used as a solution called formalin (37% w/w formaldehyde + 12% methanol)
  • also available as a solid (paraformaldehyde) which releases formaldehyde gas when heated. This is how biohazard cabinets are decontaminated by a trained technician.
  • formalin is unlikely to be a good choice for cleaning up a spill in an open lab but it might be used to treat material in a sealed container