I am trying to extract microplastics from water samples and follow the standard method. As per the standard method after digestion and density separation, the final step is filtration with glass fiber filter paper and then analysis.
But my query is in freshwater samples after extraction we are getting a few very small microplastic particles that get stuck to the membrane only after filtration and it is very difficult to get a residue for FTIR analysis.
If we give filter paper as it is for ATR- FTIR analysis then how it is assumed that all particles spread over filter paper will be detected?
As in ATR FTIR point of contact of the beam is at one point only.
So can anybody suggest how to extract microplastic particles that are stuck on glass filter paper to get particles for any analysis?
Hello Kavita Verma, it could be a totally bad idea to perform FTIR analysis of the microplastics without doing microscopy. Depending on the contamination levels of the water samples, you may be able to see the extracted microplastics but these will not be the only particles on the filter paper (some could even be on the backside from my own experience!).
My colleague told me that even prior to FTIR analysis, one may still need to check the particles using microscopy and then isolate the individual particles from the filter papers one after the other. I hope this helps!
Hello Kavita Verma,
After filtration you have to observe the filter paper under a stereo-microscope (for better identification) and confirm the particles remain are plastics via hot-needle test. Once confirmed if the particles are big enough to extract from the filter paper, you can do so using metal tweezers and collect separately for FTIR analysis. But if the particles are very small and non-extractable you can go for micro-FTIR spectroscopy for polymer identification.
Hope this helps.