I am researching on azo dye degradation by bacteria. To analyze FTIR, how should I prepare my samples? Do I need to centrifuge, add anything or subtract anything? I am using minimal salt medium with 0.25% glucose.
Depends on the FTIR method you are using, I guess you are using a configuration suitable for measuring liquids. First thing I would do is measure the media-bacteria-dye solution spectrum and media-bacteria solution spectrum. First check that it is correct spectra (absorption intensity, presence of relevant peaks...) and then see if there is any characteristic band corresponding to the dye. If there is, you can quantify dye degradation using that peak, if there is not... try processing the sample so you get a nicer spectrum, maybe.