IR Spectroscopy determination of xylene using an internal standard - Essay Example

We used a Fourier transform infrared spectrometer to analyze eleven solutions: O-xylene, p-xylene, 3 concentrations of p-xylene in cyclohexane, 3 concentrations of m-xylene in cyclohexane, and 2 unknown samples. We analyzed our samples using o-xylene as our standard to determine the concentrations of m-xylene and p-xylene in our unknown samples. Standard curves were constructed from the ratio of absorbance of characteristic peaks. A trend line showing the least square fit helped to determine the ratio of concentrations in our unknown sample.

The results obtained show that the concentration of m-xylene and p-xylene can be determined if their concentrations in the stock solution are determined. This will be used to show the various concentrations of the m-xylene and p-xylene in the unknown sample.IntroductionInfrared spectroscopy is the spectroscopy that uses the infrared region of the electromagnetic spectrum, which is a region of lower wavelength than visible light, exciting molecules to higher vibrational states in order to detect energy of the vibrational modes in your sample.

The infra-red radiation is passed through a sample by an infra-red spectrometer which uses a detector to represent the transmission in graphical representations. Infra-red spectroscopy can be used to study virtually every sample in any state of matter and the IR spectrometer utilizes FTIR spectroscopy which has improved the infrared spectra quality within a short time of analysis. This technique has been in existence since 1940’s where the instruments relied on prisms as the elements to disperse the radiations but further development has occurred which include the diffraction gratings and finally the most significant the use of interferometers and Fourier-transformation mathematical process.

Infrared spectroscopy can be used a number of ways, one of which is based on absorption spectroscopy. Isomers of organic molecules display a unique vibrational frequency; thus by analyzing a specific region of the spectrum, overlaying pure and different concentrations of a sample molecule as well as any background spectra it is possible to determine the concentration of an unknown sampleConclusionFrom the results the concentration of p-xylene and m-xylene in the two samples was determine using the Fourier transform infrared spectrometer using the internal standards.

It was observed it is possible to calculate the exact concentration of both p-xylene and m-xylene in the samples if the exact concentration of the stock solution used is known. This determines their concentration in the samples being tested.ReferencesSkoog, Douglas A., F. James. Holler and Stanley R. Crouch. Principles of instrumental analysis; Belmont, C A: Thomson Brooks/Cole, 2007.