I am working on a bioaerosol detection project with WIBS-4, also I want to exam the aerosol using fluorescence microscope. I will use an 8 stage andersen impactor to collect the aerosol, but I'm having problem with how to put the samples I collected under microscope. Most other projects I read about were using greased cover glass slide with a single stage impactor to collect the samples used for fluorescence microscope. Can I use glass fiber filter or quartz fiber filter (both are designed for andersen impactor) under microscope? Or do I need to transfer the aerosol sample from the filter to a glass slide, if I have to do the transfer, what's the general procedure for that? Thanks a lot for reading this!
Many people put thin microscopy substrates of their choice inside their impactors and collect directly on the substrates. I know this works for MOUDI impactors, but don't have experience with the Andersen impactor. Adhere the substrates to a foil disc using double-sided tape and then pull them off when you're done sampling and transfer to the microscope.
One of the easiest ways is to use carbon conductive tabs (usually for SEM imaging). Those are highly adhesive and thus can minimize particle rebounce.
Yes, Xufei -- that's the double sided tape I was talking about! Thanks for clarifying that.
I used a 6 stage Marple Impactor a long time ago and analysed the samples with PIXE. This required having the minimum mass possible in the substrate. In order to use your samples in a microscope you need an as plane as possible surface. Not to have rebounce, you need it to be sticky. Try getting a smooth surface (a glass or a polymer material) and get it covered with a very thin layer of grease (eg. you may dissolve 5% paraffin in benzene and deposit a thin film of the solution over your collecting surface, after the benzene evaporates you get a very thin greasy surface, micrometers thick. Take into account that you should handle benzene in a proper laboratory, not on the desk of you office!). Notice that the thin greasy film must be invisible to the naked eye, otherwise it is too thick. As to glass fibre or quartz fibre filters, they will be too rough for a good work with the microscope.
All of the above are good suggestions. It is best to plan your sample for examination. A minimum sample is best. A minimum sample will prevent interference for viewing the particles and reducing particle pile up that might appear as agglomeration.
Prepare a thin, sticky substrate. A thin, uniform substrate is obtained by dissolving the sticky material and placing the solution on the substrate. An example of the solution is vaseline in hexane or alcohol. Not all of the vaseline will dissolve, but what does is usually enough. You have the options for preparing the microscope sample after collection:
- touch the slide to the surface of the collected sample
- touch the slide with double side tape
- rinse the substrate with the original solvent into a container and then place drops on the slide
- place drops of the solvent on the substrate and then touch the slide to the drop
Experiment to find what works best
- Badges
- Science topic