my last instrumental analysis lab was basically about becoming familiar with using an IR spectrometer. I used a salt solution with a sodium chloride salt plate although it was not stated in the procedure to do so. the IR spectra seems to have come out fine however I'm not sure if there is any reason to not use a salt plate with a salt solution, basically i'm wondering if anyone can tell me if a salt plate in combination with a salt solution would obscure any part of the spectra of the salt solution itself?
Your explanation is long but not too instructive; I'm not exactly sure what you are asking. As long as you are examining the IR spectrum in the region of about 2-15 microns, then using salt plates is ok for looking at molecules that absorb in that region. (When you salt salt plates I assume you mean NaCl plates but remember KBr and others are salt also.)
Yea I know I was having a difficult time trying to figure out how to explain it. Basically I was using NaCl plates with the salt form of a drug although I wasn't supposed to. I was only supposed to use the free base form with the salt plates so I was wondering if testing the salt form with the salt plates would effect the spectra. Not sure if this clears anything up
To determine if using a salt plate in combination with a salt solution would obscure any part of the spectra of the salt solution, there are a few factors to consider:
1. Optical Properties: Salt plates, such as sodium chloride (NaCl), are commonly used in Fourier-transform infrared (FTIR) spectrometers due to their transparency and low absorbance in the infrared region. However, it is important to note that the salt plate may also have minor absorption bands in the infrared range. These absorption bands could potentially interfere with the spectra of your salt solution.
2. Solvent Interactions: When you have a salt solution, the solvent (such as water) interacts with the salt ions. This can lead to changes in the chemical environment and possibly affect the infrared absorption patterns of the solution. Understanding these potential interactions is essential when interpreting your IR spectra.
3. Concentration Effects: The concentration of the salt solution might also play a role. Higher concentrations can lead to stronger absorption bands that might overshadow any potential absorption from the salt plate.
In light of these considerations, it is always best to experimentally validate the use of a salt plate with a salt solution. Here's how you can do that:
1. Perform a Reference Measurement: Start by obtaining an IR spectrum of the salt plate alone, without the salt solution. This will serve as a reference to identify any inherent absorption bands from the salt plate.
2. Measure the Salt Solution: Next, measure the IR spectrum of the salt solution using the salt plate. Compare this spectrum with the reference spectrum and look for any significant differences or distortions.
3. Control Experiment: To verify if any observed differences are due to the presence of the salt plate, repeat the experiment with a different transparent material as a sample holder, such as a quartz cuvette. If the resulting spectrum is similar to the one obtained with the salt plate, it suggests that the salt plate does not affect the spectra significantly.
By following these steps, you can evaluate any potential interferences caused by using a salt plate with a salt solution and make an informed interpretation of your IR spectra.