Swabs, Contact Plates and Dipslides (Air Monitoring)
Air conditioning systems, ductwork and kitchen surfaces are prone to the build up of environmental bacterial or mould contamination which, if unchecked, can pose a hazard to health. Swab or contact plate samples can be analysed to assess the level of contamination. They can also be effectively used to assess the efficacy of any cleaning programme in place.
The swab used and held by this laboratory consists of a dacron tip swab immersed in 10 ml of a neutralising buffer.
This buffer is designed to neutralise any residual sanitizer or biocide before analysis takes place.
After extraction in the laboratory, they are analysed for total viable count (TVC) and total fungi (yeast and mould) and results presented as per swab.
Type of sample
Ductwork, air monitoring, environmental monitoring
Swabs Hygiene /Water (UKAS)
Taking swabs
Swabs must be gently removed from the tube and, without touching or handling the bud, an area of approximately 10 cm2 where possible, should be swabbed with a rotating motion. The area should be swabbed in two places, perpendicular to each other. The swab should be immediately replaced into the neutralising solution in the tube and the tube labelled with date and location of swabbed area. They should be analysed within 24 hours of being taken.
Contact plates
The contact plate is a 55 mm agar plate with raised agar surface. It is used by pressing the raised surface onto the area to be tested - this is called surface contact.
Placing the plate into an air sampler for the microbial quality of air of a particular atmosphere to be tested is called air sampling.
Contact plate samples may be taken by trained staff from Stansted Laboratories or by the client. The samples will, in general, be from air conditioning ductwork or similar.
