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Technical Data — Sampling Collection Methods

Settling Plates (Petrifilm) vs. MB-2

The MB-1 unit with an air sampler disk attached. The unit can be attached to a tripod via the screw mount on the bottom.

Air sampling must be reproducible to be an effective tool to measure before and after microbiological treatments. Settling plates are not as effective as the MB-2 self contained programmable unit. The MB-2 draws a set amount of air (from 10 to 500 liters) in any environment (turbulent, etc.). Objective measurement coupled with spatial mapping gives the requisite tools for monitoring the processing environment as well as monitoring treatment efforts.

Settling Plates

A settling plate, which is a petri dish containing either agar medium or hydrated Petrifilm^®, passively collect whatever falls into it as gravity dictates. While very simple, because it is passive, it is also non-volumetric. The volume of air sampled cannot be controlled. It is also imprecise, because it over-represents larger particles due to their rapid settling rate.

Furthermore, collection in turbulent air is seriously affected by shadowing or turbulent deposition. It is very difficult to reproduce reliable sampling results, which means that a sampling profile of a facility or production area will be very inconsistent and of little or no value.

MB1 Sampling Unit

The MB1 air sampling unit is a self-contained, programmable, battery-operated portable unit that has seen many enhancements over the past several years. Numerous industries have adopted it as a standard, and the MB1 is one of two samplers mentioned by name in Microbiological Evaluation of Clean Rooms and Other Controlled Environments (1998 USP 23-NF 24 Eighth Supplement, Section 1116). The MB1 sampler uses inexpensive contact plates and is traceable to the National Institute of Standards and Technology.

The enhancements and accessories made for the basic model allow for sampling in many different environments and under many different environmental conditions. This flexibility makes the MB1 sampler a versatile and excellent screening tool for airborne microbes. For more details, see our Product description.

Sampling Methods

For more information about the theory behind the effectiveness of the MB-2 unit, see The Science of Sampling.