I synthesized some nanoparticles, but I had to dissolve the polymer (PLA) in chloroform, and I'm not sure how to know if there isn't chloroform in the colloidal suspension after solvent evaporation.
Obtain an IR spectrum. C-H stretching is shifted compared to the aliphatic C-H stretching band. Also, a large band is obtained for C-Cl bond. Depending on how much polymer you have...you can have solvent trapped in it.
Obtain a Raman spectra, you can observe a shift in C-H region. This shift is due to interaction of C-H group with nanoparticle. analize carefully the spectrum, because contain information of all system (nanoparticles-PLA-and solvent). if you need more information, do not hesitate to contact me. Kindly regards
Thank you so much for the answers Jhony and Francisco; I'll try with Ir spectrum.. my university has the equipment... but RAMAN, we didn't have one :S but, again thank you so much... I will talk to you again ;)
You may also prepare a sample for XPS which is also known as ESCA analysis. When chloroform is present, you should see the C-CL binding energy signal.
I AGREE WITH FRANCISCO RIVERA.....The exact way is to do FTIR and FT raman spectra. You can also do the preparation even in heating condition (i.e at 70 - 80 deg Celcius to completely evaporate the solvent) if its not affecting your vehicle or active constituent.
You can also pass a stream of nitrogen gas through out your nanoparticles to ensure complete removal of chloroform. We tried this in our lab and it was successfull.
Do the gas chromatography for estimating the solvent in the nanoparticle.
Respected Tatiana, I have worked with it. If you can pass a stream of nitrogen gas through out your nanoparticles it ensures complete removal of chloroform. We tried this in our lab as well and it was successfull.
How the entrapped solvent will be removed if you pass the nitrogen? .....she has mentioned that its in colloidal form ( i think its not yet separated from the stabilizer soln). if its separated and dried, then heating upto 60-70 deg celcius will help for complete removal of CHCl3. This temp will not affect the PLA too.(M.P - 150-160 deg celcius)...
Use DCM instead of chloroform. If not possible check IR of material for absence of C-Cl strech in between 600-800 cm-1. Another option is remove the solvent under reduced pressure using rotary evaporator.
Well, this week I'll try remove the solvent under reduced pressure with rotary evaporator, and also.. I'll do it the IR spectra from my NPs... thank you so much to all of you for your help ;)
You can do a direct ATR-FTIR spectrum of your nanoparticles and compare them with a spectrum of chloroform. I'm sure you'll find some region in the chloroform spectrum that shouldn't belong in the spectrum of pure nanoparticles.
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