Abstract: A method of detecting substances, if desired in biological fluids, by using detection reactions based on chemiluminescence, wherein a luminophore, preferably having an emission wavelength longer than about 500 nm, is raised from its non-excited state into an excited state by electron transfer due to the detection reaction, and subsequently the radiation emitted by the luminophore when falling back into its non-excited state is measured. The chemiluminescence reaction is based on the oxidative decomposition of optionally substituted oxalates or oxamides, the radiation emitted by the luminophore when falling back into its non-excited state is of longer wavelength than the nonspecific background radiation of the reaction. The luminophore can be accumulated prior to the chemiluminesence reaction. Nonspecific background radiation of the reaction can be quenched.