Abstract: An apparatus chemical analysis of a sample includes: a chromatographic module configured to separate compounds that make up a mixture to be analyzed and which is configured to determine a linear retention index of the separated compounds; a module for mass spectrometry, configured to detect and/or determine mass spectra of the separated compounds, from the chromatographic module; a module for IR spectroscopy, configured to detect and/or determine the IR spectra of the separated compounds, from said chromatographic module; at least one processing unit configured to receive data, acquired by the chromatographic module; the module for mass spectrometry; and the module for IR spectroscopy; and at least one memory unit associated with the at least one processing unit, having at least one organized file containing the retention indices, the mass and IR spectra of a plurality of known and predefined compounds.