Fourier Transform Infrared Spectrophotometry (FTIR) utilizes the principle that different substances will absorb infrared light with a unique pattern.
A powder sample is placed on a stage in the instrument. The instrument passes different wavelengths (or colors) of infrared light through the sample. An infrared light detector in the instrument measures the amount of light that passes through the sample as the wavelength is varied. These results are recorded on a chart and this chart forms an Infrared spectrum that then can be compared to drug standards or a library database.
