Science Buddies: "Ask an Expert"

I'm in grade 11. This year I participated in the Isef competition in my country - Vietnam. We did project about LNR - liquid natural rubber. There are so many kinds of LNR. But we chose HTPI - hidroxyl terminated poly isoprene. To confirm that there is -OH in our substance, we used IR spectrum. When we did a presentation to report our work to the professors, they required us to redraw the spectrum to emphasize in the wavenumber of -OH. They said that there is a software to do this kind of work. However, we forgot to ask her. So can you show me the software and how to download them.
Furthermore, to prepare our substance, we use metanol and toluen as solvent. They are poisonous, and are not preferably accepted in this competition. What can we do to confirm that we did this experiment safely?
I would really appreciate your help!

Nho Xanh

Hello and congratulations on what sounds like an excellent science project!

Toluene and methanol are indeed toxic to humans and should be handled in a fume hood and disposed of in approved waste containers. Your supervisor or teacher can provide a statement of Safe Lab Practices and if there is a chemical/biohazard safety division where you work you can include an approval statement from them that your experiments were done according to proper guidelines.

As to how you can redraw the IR spectra, I would have to know what instrument was used to obtain the spectra and what software it was running. My experience is that the software package that comes with the IR spectrograph is capable of taking the data file you obtained and converting it to a different form, hopefully what you want.

What exactly are the professors asking you to do with the spectra? Did you ask them how to do the conversion? They should be the ones who know how to do this and help you. Otherwise, you should call the company that makes the IR spectrograph and ask them how you would redraw your spectra to emphasize the -OH moiety.

I don't know what your professors want, but why couldn't you simply print the spectrum and manually accentuate the -OH portion with a highlighter or colored pens and labels?

Please post again and let us know how you are doing.

Sybee

Hi, it's me again. Thank you so much for your reply.
About the IR spectrum, in my last presentation 2 weeks ago, actually I had done the same thing that you recommended. But the professor didn't want it. They said that this spectrum is not informative enough, because they said when there is smear in the substance, the wave can also appear. (I don't speak English as a native language so maybe some words i use sound hard to understand, please pardon me). And they said that there are many waves that we can explain clearly, so they only want us to redraw it. Unluckily, they were invited by my teacher so that we don't know them very well to ask them outside the classroom.
About toluene, after reading your reply, I and my partner had gone to the tutor for the statement. Only at that time did he recognize that we are participating in a competition for high school students. (He only helped us at the experiment, not at the competition).
Now, my friend and I are filling some papers to join in the national competition. So right now we don't make any progress in the experiment. That is very sad!
Thank you again to reply to my question!
If there is other problems, can you have us again?

I am happy to help you!

I am trying to understand what it is your professors are asking for. Do they want you to run the IR spectrum again? If there is a problem with a 'smear' you should be able to correct that and obtain a clear IR spectrum. I remember when I was doing IR spectra and using salt plates for the test compound. If the slightest bit of water got onto the plate it caused a problem with the machine reading the spectrum. Was your methanol and toluene really dry? Also, be VERY careful to only hold the plates by the edges. If you get a fingerprint on the surface it can alter your spectrum. What did your background scan look like?

If you can do some more IR runs, maybe with different amounts of your analyte or different solvents. Is your machine able to do Fourier Transform? My machine was a Perkin-Elmer 1600 but that was quite a number of years ago and newer machines should be better. FTIR will give you a cleaner spectrum.

Let us know if you have more questions.

Good luck!

Sybee