The MD8 AirScan utilizes the gelatin membrane filter method for collecting airborne microorganisms. This is the only sampling method that boasts a 99.9% retention rate for airborne microorganisms compared with 40%-60% for other collection methods and a 99.9% retention rate for airborne viruses. Due to the porous nature of the filter, all bacteria-laden particles are captured, regardless of size and the residual moisture content of the filter prevents desiccation of the retained organisms. Filters are pre-sterilized (gamma irradiation), single or triple bagged, H2O2 safe and disposable. 

After sampling, there are two filter transfer methods: direct and indirect. Using the direct method, the filter is placed directly on an agar nutrient plate. The gelatin filter dissolves, leaving the microorganisms in direct contact with the plate. Using the indirect method, after sampling, the gelatin filter is dissolved in a sterile solution. The solution is then membrane-filtered and the filter disk is placed on an agar medium. The indirect method is useful for special evaluations, such as when inhibitors are present in the air being sampled, high colony counts are expected or when microorganisms collected are to be incubated on several different agar types simultaneously. When the virus concentration is to be determined, the indirect method must be used so that retained viruses can be cultivated in the solution and analyzed by virological or molecular biological methods.