Dear Sirs,

We are a plant tissue culture, where we fumigate the clean rooms every weekends. We use Formaldehyde 37% along with Kmno4 for fumigating. Please let us know whether the concentration (37%) is enough to kill all the organisms or we have to go for high concentrated formaldehyde.We fumigate for not less than 30 hours.

Regards

R.Sankara Narayanan

Dear,

There are no formaldehyde solutions on the market with concentrations above 40 %. (Formaldehyde solution - Ph Eur - contains 34.5 to 38 % w/w of CH2O with methyl alcohol as a stabilising agent to delay polymerisation of the formaldehyde to solid paraformaldehyde)
Formaldehyde solutions in water become cloudy by polymerisation. This reaction is accelerated by concentrations above 40 %.The concentration of gaseous formaldehyde depends not only on the concentration of the solution but also on the evaporated volume and the temperature. At 21° C the maximum concentration is 1,75 mg/l ( Hygiene Hospitaliere Pratique ).

For more details I refer you to the answer on question Q00067.

Kind regards,
Wim Renders