Slit
Sampling
Procedure - Agar plates with dry, even surface are selected and marked to record the sampling area, time of sampling, duration of exposure, volume of sampled air etc. The slit should be unblocked and free from dust and if necessary may be cleaned with alcohol and by inserting the edge of a stiff paper. The door of the box is opened and the plate is placed at the centre on the platform.
The distance between the agar surface and the slit is adjusted to be 2mm. At the correct time, the motor that rotates the plate and the suction pump that evacuates the sampler are switched on and the negative pressure is maintained at -22.6 mm mercury. After sampling for the time necessary to collect the required volume of air the suction pump and the rotor are switched off.
