I have two similar filter papers say PTFE type of different brands. How do I validate to prove either of the filter papers are in standards to use for the research work in sampling PM 2.5 air pollutants.
Usually on filters not only the expected PM is accumulated (i.e. PM 2.5). To validate the efficency of the filter I would use a SEM (Scanning Electron Microscope) or a similar methodology to estimate the quantity of particles accumulated on filter of a specific range (i.e. between 2 and 3 um). The brand filter that shows the highest accumulation on that range (by sampling the same known dust) is validated and is better.
Mr. Gregorio
Thanks for you comments. What I mean is, do we have any specific standard test methods to validate the similar filter papers of different make?
Actually I do not know any standard methodology for filters valdiation. We are working on it and we are using different technique for filters validation.
You may consider including standard methods in your bibliographic review. Standard methods are not supposed to cite commercial bransd of materials or Equipment, so they describe their necessary properties.. ISO 25597, e.g., entitled "Stationary source emissions - Test method for determining PM2,5 and PM10 mass in stack gases using cyclone samplers and sample dilution", describes the intrinsic characteristics of suitable filters for PM2.5 dertermination. In example, you can reed, under clause 7.12:
We have mass content of chemical elements in the atmospheric aerosols on filters AFA-HA-20 (Ogorodnikov 2011). Then ICP-MS method.
The answer provided by Marie-pierre Strub is comprehensive. However, every time, it is not possible to test each filter paper for its adherence / compliance to these properties.Any supplier can claim to have filters meeting all these qualities. In one of the experiment, a locally supplied filter was used for PM2.5 collection. The collected PM2.5 was then used for metal analysis by extraction in n-cyclohexane. To our surprise, part of the filters got dissolved in n-cyclohexane. Following this, Whatman filter was also extracted using same solvent. The Whatman filter was intact. I have the photograph of both. If you need the photograph, kindly send me the email, I will send it to you. This indicate that besides specification, the brand value also matters. If the local filter paper supplier is asked to prove the fitness of their filter, they will happily produce a certificate from Govt. authorised laboratory, which indicates that their filter is meeting the required specification. How this is possible? The local supplier procures Whatman Filter, changes its cover packing and then hand it over to Laboratory for characterization. The laboratory analyses the filter very honestly and produces certificate which fulfills all the quality criteria.
How is is done at USA? In the speciation network, the monitoring station is managed by one agency, which maintains all equipment running. The filter paper is pre-processed and loaded by another agency. The exposed filter is then packed sent to the third laboratoey for pre-conditioning, weighing, speciation etc. All are kept separate, still the result has to come. This ensures quality and control.
HI Kariam
Thats a valuble information what you have shared. But in this case, the company has produced the test certificates authorized by IIT-Delhi. For your information the name of the company is Micro Separations located at UP.
My email ID: [email protected]
please do send me the photos of what you have discussed.
Hello ! EMR,
I am from Civil Engg. Dept., IIT Delhi. The filter I had analysed is not from the company you have mentioned. I have sent you a detailed mail on the given ID with photographs of dissolved filter.
Hi KV George
Received your mail. Will discuss in detail soon.
Once again thanks for your valuable suggestions and information which gave me a knowledge in this concern.
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