Hello,
I am currently carrying out an OQ for our compressed air system in a non sterile Penicillin Plant. I am stuck on a test method on how to carry out such a test. Can anyone help?
Please Reply to validation @athlone-laboratories.com
Kind Regards,
Roisin.
Hello Roisin,
Did you mean to say, what are the tests to be done in OQ of compressed air.
Pressure monitoring test:
To verify that the compressed air pressure required at each point are as per user requirement for consecutive 3 days.
Hello Chawla, I know the tests that have to be carried out, I am just unsure about how to carry out a test for Total Viable Count, and detection of Ecoli etc… i.e, how to collect a compressed air sample and send it off for Microbial testing.
Kind Regards,
Roisin.
Hi Roisin,
Are you performing the testing yourself or contracting out?
We are currently writing a procedure to perform in-house. We have a flow meter with regulator which has a plate/filter housing attached (Key Instruments). The flow meter is attached to the compressed air supply and regulated to the required air flow (litres per min). The plate is then sent to a microlab for cfu results.
We have still to work out the finer details of flow rates, media for collection etc. or may still contract out.
Will drop you a line when I know more.
Hello Erez,
Thank you for you’re reply. I am hoping to do the test myself in-house. I’m not too worry about flow rates, just as you say, the medium to store the sample so it can be sent for testing. You have given me ffod for thought!
Kind Regards,
Roisin.
The instrument which we are using for measuring microbial detection in the compressed air is “M air T isolator”.
1000L of air from the pendant can be exposed to media plate.
Cheersss…
Hi Roisin,
A simple test that utilizes air impaction onto growth media is suggested. A general sampling method would be to reduce the pressure of the compressed air line (which usually is 160 pounds per square inch or greater), using a built-in or external regulator; attach a flow meter, and adjust the flow to a suitable rate, for example, 1 cubic foot per minute; and attach the air impaction sampler which has been prepared with a Petri plate. You should select parameters best suited for your application or those noted in ISO 8573-4.
The Slit Sampler (also known as the slit-to-agar sampler) is a device which utilizes a rotating stage which holds the Petri plate. The air impacts the surface of the agar with whatever organisms are present, the organisms become impinged onto the agar, the plate is incubated, and the organisms are allowed to grow. ISO 8573-7 offers further details and should be reviewed before testing is conducted. Two companies that manufacture Slit Samplers are New Brunswick Scientific and the Barramundi Corporation.
The general concept is that compressed air, under reduced pressure, called “Partial Flow” is forced over the surface of a Petri plate. The Petri plate is 100 millimeters in diameter or greater, based on the sampling device used. Bacteria are impinged onto the surface of the agar. Subsequent incubation of the Petri plate will allow the bacteria to grow. Care should be taken to ensure that equipment used has been properly disinfected in order to minimize the introduction of bacteria not associated with the compressed air supply. A negative control should be used as a qualitative measure, and the end point to be tested should be purged and aseptically cleaned to minimize false results.
Important factors to consider when developing a sampling plan include:
• If the air system is static, a longer sampling time may be appropriate;
• If the air system is in use, a shorter sampling time may be appropriate Caution should be taken to minimize the possibility of confluent growth.
The agar used can be a broad spectrum agar such as Soybean Casein Digest Agar (SCDA), commonly referred to as Tryptic Soy Agar (TSA) which will allow the growth of most non-fastidious organisms. A selective agar may be used if you are trying to isolate a certain type of microorganisms, such as Sabouraud Dextrose Agar, which is used for the cultivation of fungi.
Following incubation, the agar plate(s) are read on a colony counter and recorded. A detailed description of sampling techniques and incubation periods can be found in ISO 8573-7. It is recommended that the viable organisms be identified in order to assess the impact on the environment and product.
It may be beneficial to conduct particle counts of the compressed air lines before conducting microbiological counts to more accurately determine the microbiological sampling time. This can be performed under the general rule that the higher the particle count the higher the microbiological count. Correlation between these two variables should be determined so that particulate testing can be used to predict future microbiological results.
Regards,
Hi All,
Well explained by Mr. Shoaib, however just to add readily available Air sampler Instruments are being used across the industries for Compressed Air Sampling. As stated above very well. Air is sucked through air sampler & pass through media [ As we are using for routine product pathogen / Bio burden testing i.e. SCDA / SCA etc] once the sampling get over incubate & count…establish a stringent limit which most suits your needs…one can refer regulatory limits also.
Happy Reading !
Good explanation Ash!sh…
Very exhaustive & good explaination by Shoaib. I think as per ISO 8573, we need not worry about flow rate of air during sampling if we look at all 9 parts of ISO 8573, only we need to sample minimum 1 cu mtr volume of air specifically for viable & non viable count. This too is based on limitation of set up used for all other testes like moisture, oil/hydrocarbons etc.
Rgds
Ravi Dhanbhar
Information provided by shoaib khan is really very interesting and comprehensive…It helps to understand what actual concept is.I just sharing some point related to microbial sampling of Air system:
Microbiological air sampling in clean rooms and other controlled environments usually requires the sampling of large volumes of air (at least 1 m3). It is also very important that samples are representative and the results of sampling accurate enough to ensure that the air meets regulatory standards, or guidelines. It is therefore essential that air samplers are properly validated and regularly calibrated to ensure accuracy. There are a number of points to consider.
Physical efficiency of the sampler – the relative efficiency of the sampler in collecting particles over a range of sizes.
Biological efficiency – the relative efficiency of the sampler in collection of microorganisms on a surface or in a liquid so that they are viable and can be counted.
validation of the instrument for its intended application and environment.
The flow rate of the sampler – with large sample sizes, the flow rate of air through the sampling head is critical to the accuracy of the result.