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Biological Indicator – Formaldehyde

Formaldehyde is a chemical gas, an alkylating agent that can kill microorganisms by destroying proteins and nucleic acids. 

Product description

SSI Diagnostica’s biological indicators are microorganisms (spores of Geobacillus stearothermophilus, ATCC 7953) prepared on filter paper as carrier material and packed in primary packaging consisting of transparent plastic film and paper that is permeable to gas and water vapour.

Formaldehyde indicators are produced in accordance with the EN ISO 11138-5 standard and are supplied with the following specifications: an initial microbial count of at least 10⁵ CFU/unit and a D‑value of at least 12 min. in a 1 mol/l solution of formalin at 60°C.

How to use

Important factors for sterilisation using formaldehyde are gas concentration, relative air humidity and temperature. The sterilisation conditions may, for example, be 70 mg/l formalin, >90% relative humidity, and a temperature of 70°C. High relative humidity is crucial for killing microbes effectively. Due to the low sterilisation temperature, the process is intended for sterilisation of heat-sensitive instruments such as endoscopes with sensitive optics, single-use medical devices or implants. Formaldehyde has also been used to decontaminate cleanrooms and is used to a certain extent to decontaminate isolators and LAF benches, but, in this case, it can be difficult to maintain sufficiently high temperature and humidity.

The disadvantages of formaldehyde sterilisation are that it is difficult to measure and therefore to control the physical parameters and to achieve adequate humidification. Moreover, formaldehyde is a carcinogen that irritates the mucous membranes and can trigger allergies, and it is important to degas the products once sterilisation is complete. Because of the resulting uncertainty, SSI Diagnostica recommends that sterilisation testing using biological indicators be carried out for every single individual sterilisation cycle. Biological indicators are also used for validation/revalidation.

Product range

The indicators are supplied in packs of 6. 

75623 6-unit pack without culturing, 10CFU per unit  
98407Culturing of 6 units


Please find the available downloads here.


Click on the link below to download the IFU.

Formaldehyde Indicator

Simpler for the better

If you work within the field of microbiology, you might be familiar with Occam’s Razor. At SSI Diagnostica, we champion a slightly adapted version of this principle:
The simplest solution is usually the best one.

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Please, reach out if you have questions, comments or requests.