Abstract: The cited detection technique is based on quenching of the phosphorescence of biacetyl by suitable analytes. The sensitivity of such quenching is dependent on the bimolecular rate constant of the quenching reaction. Values for this constant and for the estimated limit of detection in aqueous 83.7% acetonitrile, water or hexane are listed for various chloroanilines, amines, aromatic N compounds, S-containing compounds, chlorophenols, aromatic and aliphatic hydroxy-compounds, and inorganic ions. The detection limits are often very low, e.g., 1 to 10 nM. The rectilinearity of the relationship between signal and concentration. can be extended by use of electronic signal inversion techniques. Application of this detection method to flow injection analysis and HPLC is demonstrated.