Hi,
I need to sanitize some plastic tanks after sampling different kinds of environmental samples, in order to be sure to do not have a carryover of bacteria. I was thinking about chlorine solution, but which concentration? I have to make sure I don't pollute my sample with it, but still have it effectively sanitizing the surfaces.
Thanks,
Silvia
If I understand correctly, you need to clean plastic tanks to make sure you reuse them to take samples again without bringing microorganism contamination from previous sampling?
House hold sodium hypochloride (AKA chlorine AKA Bleach) is 5% to 8% active.
Industrial sodium hypochloride is 12.5% active.
Pool sodium hypochloride varies widely depending on source.
A 1:20 dilution of household bleach would be enough sprayed on entire surface and left for 30 minutes to 1 hour (gloves, safety goggles, apron etc....if tanks are big...wear gas mask).
If you decide to use sodium hypochlorite remember you have to completely remove it or neutralize it. If you do not need "sterile conditions" you can rinse it with plenty of water. If you need sterile conditions you need to autoclave water and let it cool to use for rinsing. How do you know if you removed it? Get chorine strips from a pool supplier. You can speed the removal process by adding a small amount of sodium thiosulfate diluted 1:10...before rinsing to partially neutralize the chlorine. If sterile conditions are needed and the tanks are just a few gallons in size, sterilize sodium thiosulfate with bacterial filter (0.4 micron filter) or just use enough water till no chlorine is detected from the tanks
Another option is dilute phosphoric acid (industrial grade is around 75%), 1:10 dilution would work....Remember when you dilute chemicals NEVER add water to the chemical...Add the chemical slowly to water with mixing...again gloves and googles. After 30 minutes to 1 hour you need to wash it off completely....How do you know if you removed it? Test rinsing water from the tank with pH paper which must give you pH similar to the water that you are using to rinse.
Another option...use sodium hydroxide solution (AKA caustic soda) 5% spray...30 minutes to 1 hour ...then rinse ...pH paper can be used to determine when alkali is removed. Again, gloves, goggle apron etc. To speed up process: Rinse well AT LEAST THREE TIMES with water and drain alkaline water then spray a very dilute solution of pool acid 1:30 dilution. Continue rinsing till pH paper indicates same pH as water being used to rinse.
Whichever method you use, keep in mind that the tanks must be scrubbed and surface cleaned of deposits ...organic material etc before disinfection.
What we do in our lab is we sterilize the plastic with alcohol. Then uv treatment in a laminar flow. And we lastly autoclave it. We get zero to negligible bacterial contamination.
If however lab facilities are unavailable. I believe @Nicolas Canello has provided a great answer. Regards
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