Qualitative determination of different amounts of adulterant in a liquid using a double aperture common-path interferometer

This research shows the application of a Double-Aperture Common-Path Interferometer (DACPI) to quantitatively determine different amounts of adulterant in a liquid. The method compares the interferograms coming from two glass containers, the first containing a sample of commercial rum and others alcoholic drinks as rum, tequila and brandy and the second containing a sample of the same species of these alcoholic drinks, added with different amounts of methanol and water as adulterants. The phase of each group of interferograms is obtained using traditional phase-shift methods. Qualitative experimental results of the phase differences between the original sample and the different amounts of adulterant are shown. This technique shows an effective, immediate and reliable way to determine up to 2% of the amount of adulterant in a liquid without the requirement of colorimetric processes, laboratory analysis or spectrometry, among others.