Advances in Air Monitoring

Active air sampling is also used to identify microbial contamination in compressed gasses, which come into contact with product at numerous points in any production process.

Microbial contamination can exist in the valves or lines that are used to feed gas and air into critical, aseptic manufacturing environments. When testing compressed gasses, ensure constant air flow and consistent air sampling for accurate and reliable sampling. Some compressed gas monitors provide automated operation and conversion of the compressed air or gas sample, which can be at pressures of up to 5 bar (73pounds per square inch), to atmospheric conditions. Automated operation and short-duration, high-volume sampling reduces the time and effort required for monitoring and validating aseptic conditions.

Particle Counters. Particle monitoring of ambient air is conducted to quantify non-viable contaminants in the air and to determine the quality of air in controlled environments. Quantitative particle data often also provides an indication of the status regarding viable contaminants because most airborne microbes adhere to particles.

When selecting an air particle monitoring system, companies must choose either preinstalled or portable particle counters. There are pros and cons to both types. In many pharmaceutical production facilities, the particle counters are preinstalled at specified locations. When the infrastructure of the facility allows for preinstalled particle counters, the systems have proved very convenient.

However, many companies opt for the flexibility of portable particle counters.

MAS-100 CG Ex

The traditional membrane filtration method for air monitoring involves numerous steps including sterilization of the membrane, transportation of samples, the setup of the testing environment, and the membrane transfer. Additionally, the membrane apparatus uses a significant amount of energy for the autoclaving cycle, which can prove costly. The MAS-100 CG Ex air monitoring system eliminates associated setup. To validate the method, we have compared the MAS-100 CG Ex air sampling method to the traditional membrane filtration method.

The MAS-100 CG Ex is an air sampling system which is based on the well-known impaction principle of the MAS-100. The microorganisms are directly impacted on a 90 millimeter standard petri dish filled with culture medium. This air sampler is specially used for the microbiological monitoring of pressurized gases that come into contact with finished product. The microorganisms are collected under working pressure, without risking a sublethal damage by the following decompression. The suction volume of 100 liters/minute is electronically controlled over a pressure range of 1.6 to 10 bar absolute pressure. Unlike other systems and methods, sampling is always performed in the defined pressure range. The instrument is delivered as an ex-proof version and thus is suitable for use in explosion-proof zones. By default the MAS-100 CG is calibrated for air, nitrogen, argon, and carbon dioxide, but it can also be calibrated for other gases.

Taking ISO standard 14698-1 into account, the test method using an MAS-100 CG EX and the membrane filter method is compared in a given pressure range. Both methods are applied under identical test conditions. Compressed air is used as the pressurized gas. Since ISO standard Annex B (Guidance on validating air samplers) contains no instructions regarding the generation of aerosols in the pressure range concerned, this methodology has to be self-developed (the spinning-top or spinning-disc aerosol generator cannot be used in this pressure range). By using a self-developed ultrasonic nebulizing chamber, the spore suspension of Baccillus subtilis variation niger given in the ISO standard can be nebulized and then the microbial count is determined by membrane filtration or by the MAS-100 CG.

With both methods, a series of 10 individual samples is tested on each of three different days. The microbial recovery attained with the MAS-CG is expressed – according to the ISO standard – as a percentage of the membrane filtration recovery. Additionally, the differences between the two procedures are checked statistically using the t-test.