Abstract: Method for determining the total protein content or individual amino acids in flour, cereal flour and/or leguminous products or other substances by means of fluorescence analysis. The proteins and/or the individual amino acids are treated to attain a fluorescent effect or are self-fluorescent. The proteins and/or the individual amino acids are brought into suspension in their unpretreated form. The suspension is then fluorometrically measured by means of vertical transillumination. An apparatus is provided for practicing the method and comprises a primary radiation source for emitting a primary radiation to excite the fluorescent material, optical means for directing the primary radiation in a vertical direction onto the proteins and/or amino acids in suspension, at least one vessel for holding the suspension, through which the primary radiation can pass in a vertical direction, and receiving means and evaluating means for measuring the fluorescent radiation.