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WANTED: Suggestions on how to decontaminate with formalin/formaldehyde - (Sep/05/2012 )

Working as a labengineer, my boss told me to decontaminate the incubator with formaldehyde and handed me
an article explaining how this would be done using an electric frying pan as heat source.
I am not so keen on trying this out, since I dont understand where the fume would go once the decontamination
procedure is over...

Or perhaps suggest another method, which is less dangerous?
Any and all suggestions are welcome!

/MSc Mini


Hi MScMini,

If I would be you I would not try to use formaldehyde to decontaminated anything. There is another products to do it much better and with less risk than that. We usually use Deconex, although it smells a bit. Recently we changed to Barrycidal, it works really good, it is very rapid and it is recommended for bacteria, virus and fungi decontamination.


IIRC the formaldehyde can be neutralized with ammonium carbonate, but I don't recall exactly how this works, or if it really was ammonium carbonate that was used.

Formaldehyde is extremely toxic - permitted safe levels in most of the world are less than 2 ppm, and the fumigation is most effective above 20 deg C and 65% humidity. If the system gets too hot an explosive formaldehyde/air mixture can be generated.

Note that you need some way of effectively sealing the incubator to prevent the gas from escaping into the surrounding environment, and you need to be sure of the local regulations surrounding this sort of work (e.g. health and safety rules, disposal of waste materials...)!


Thank you for the input!
The article I mentioned said to use ammonium bicarb for neutralizing the formaldehyde, but I cant fit 2 heatsources in the incubator beacuse I need to vaporize both the formaldehyde and the ammonium bicarbonate.

I have tried other things before, but this is a persitant fungus.. First time I just took everything out and wiped with 70% ethanol and the infection came back.
Second time I took everything out and sprayed with 1% virkon on all parts and inside, left it for 10 min, before wiping it with 70% ethanol. Third time I soaked the fanwheel in 1%virkon together with all nuts and shelves and panels overnight. Wiped them off with 70% ethanol and it still came back.
The last time I used Pharmacidal on all parts and inside the incubator and left to work before wiping it off with 70% ethanol.

I can see the fungi growth inside the incubator.. I have tried different medias, opened new media and what other ideas I found here and other places.

This is his final solution, but I think that there must be better alternatives?!


Fungus in an incubator is pretty much always a problem -the only real solution is to regularly clean out the incubator. I find that this is best done by removing all the removable parts (including screws etc) and washing in detergent, rinsing and then autoclaving those parts that can be autoclaved. The other parts can be soaked in virkon or barrycidal or similar products. The inside of the incubator needs to be cleaned out with detergent, then with virkon or similar products, wiped down with lots of 70%. Teh removable parts should then be returned to place, spraying with 70% before inserting.
This should be done a minimum of once a month. Water should be replaced at least weekly.

Flasks should be wiped down with 70% before placing in the incubator to remove any residues of medium on the outside, which are one of the bigger causes of fungal growth on shelves.


The incubator is sitting empty, part from a dish and a flask which contained only media when I put them there.
Now they contain more.. *sigh*

Water is replaced each friday (by me).
I set up a routine to clean the incubator once a month, but I've only been here 3 months..
I now suspect that my boss is less than happy, but I ordered a company to come and ozone spray the intire incubator room including the incubator.
It was cheap but I hope that it will end atleast some of my problems.

Once the ozone has cleared I will set up another dish and flask to check for spores.


It sound familiar to my this problem...mmmm, The same in my previous lab. First, if it is possible you should clean your incubator with Deconex. Second, autoclave all the parts and also the incubator (I suppose that it has an autoclave program, hasn´t it?). Third, fill the incubator only with autoclaved ddH2O. It is not necessary to replace the water every week, only when levels are low. And forth and very important... check if your culture room is really clean. Spores will not be resistant to Deconex and autoclaving, or Virkon as you used, what means that you have a source of contamination from somewhere else... air-conditioned filters, dirty floor, not positive pressure in your room...


I have no possibility to autoclave panels from the incubator.. I use only Millipore ultrapure water from an Elix3 which is proprely maintained.
There is no automatic decontamination program in the incubator (nuaire 5500).
As i said, there is a firm coming to ozone treat the room today (and the whole weekend) so I hope it will be clean on monday ;)

Fungi grows in layers (or so a green biologist tells me) and may need several cleanings before being completely removed.

Anyway I put my new hope to the ozone-guy..


After a week of waiting and wishing; partial success..
I had no growth in the dishes I put in there for test, but in the water pan..
I am refilling with autoclaved water as suggested by Akdor but I am afraid the
damage is already done..
Could the problem be the water system??