Abstract: A method and apparatus for identifying and distinguishing fluids and for recognizing contamination of a fluid, which method and apparatus utilizes spectrographic analysis of control samples of known fluids and then spectrographic analysis of unknown fluids to generate optical signatures, finger prints and/or profiles of data and processed data relating to the relative intensities of light at selected wavelengths; and then, through comparison of the various signatures, fingerprints and/or profiles, provides determinative information as to contamination or non-contamination of the unknown fluids; after which appropriate operation control is effected and/or exercised.