Unknown Identification by Ir and Gc

The purpose of this experiment is to confirm the identity of an unknown compound using a Fourier Transform Infrared (FTIR) Spectrometer and a Gas Chromatograph (GC). Using lab safety precautions, an unknown compound will be selected and the number assigned to it will be documented. The unknown compound sample chosen will be one of the following: 4-hepatone, cyclohexane, butyl acetate, 1-propanol (propyl alcohol) or toluene determined by the instrument used.

The procedure used to perform the operation of the Gas Chromatograph in identifying the unknown compound I selected was done using several steps. I drew 1ml of air into the syringe, then 0.5ml of my unknown compound, followed by 0.5ml of the mixture (of all five of the unknowns), then finally 1ml more of air. I made sure that the computer was ready to perform the identification process and proceeded to insert the syringe into the injector port vertically applying pressure to both the plunger of the syringe and the triangular button it rested on simultaneously. I then removed the syringe and waited for the chromatogram to print. I then compared my printout to each of the sample compounds to identify what my unknown compound was.

The procedure used to perform the operation of the Fourier Transform Infrared (FTIR) Spectrometer also required several steps. Using the hood, I placed a couple drops of my unknown compound onto one of two salt plates. I then sandwiched the plates together and placed them into the sample holder securely. I then placed the sample holder into the reservoir inside the FTIR Spectrometer and closed the cover. Following the steps outlined on the computer program associated with this instrument, I filled in my name, sample number, and began the identification process using the instructions provided. When the process was complete, I removed my printed spectrum from the printer, cleaned the salt plates and returned my unknown compound to the return tray.

By using each of these instruments, I was able to identify my unknown compound as toluene. The data/report sheets are attached.

In completion of this lab, I learned how to physically use a Gas Chromatograph and a Fourier Transform Infrared Spectrometer to determine the identification of an unknown substance. Overall, I thought that this lab went very well. It was neat to see the results immediately and to compare the printouts with each of the already-printed sample sheets to determine what my unknown compound was. I also thought that it was interesting to learn how these instruments were capable of completing the identification process. The science of it seems quite involved, yet extremely interesting to learn.