Method for filter selection of binary configured for determining smallest concentration changes in substance mixtures is provided wherein one or a plurality of low-concentration lead components can be reliably detected in the presence of higher-concentration matrix or background components using the selected broad-band binary filters. The spectral power transmitted or reflected by the substance mixture is detected by a plurality of photosensitive detectors which are spectrally broad-banded and provided with binary filters, the detector signals being used for exact determination of the substance concentrations.
