I used to analyze with a FTIR, however, many limitations when reading really small particles since they're not properly contact with the crystal. Some suggest using NMR. Any expert advise advise much appreciate.
In case those particles are made of thermoplastics and dissolved in certain organic solvent, dissolve the particle(s) using a small amount of solvent (less than 1 cc) and make a very dilute solution. Then mix the solution with KBr powder (300 mg) and evaporate the solvent. The polymer will deposit evenly on KBr powder. Dry the solvent very well and press it into a KBr pellet. The transmission spectrum will give you a very nice spectrum, albeit weak intensity. If you have 10-100 microgram of the polymer, it should be well within the detection limit.
Thanks dear Leonid V Vladimirov for the suggestion. I will look around for an AFM-IR, and most likely we do not have a one locally. Not even a micro-FTIR, I am really stuck with analizing micro level particles.
Dear Artur, yes we use ATR - FTIR. i I am checking the microplastic in seawater, where we get only couple of micro size plastics which only can see from a microscope and cannot make a pellet. I know that micro-FTIR would be the solution, but we don't have a such locally.
In case those particles are made of thermoplastics and dissolved in certain organic solvent, dissolve the particle(s) using a small amount of solvent (less than 1 cc) and make a very dilute solution. Then mix the solution with KBr powder (300 mg) and evaporate the solvent. The polymer will deposit evenly on KBr powder. Dry the solvent very well and press it into a KBr pellet. The transmission spectrum will give you a very nice spectrum, albeit weak intensity. If you have 10-100 microgram of the polymer, it should be well within the detection limit.
Do be independent from addional sample preparation steps I propose a Raman or an IR microscope. If want to archive more detailed results coupled chromatic techniques for dissolvable fractions or elementary analysis might be reasonable.
TGA or solid nmr might come handy. Microscopy should also give you idea if contrast is obtained in visible or polarised light. Just run an image analysis software on photograph.