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.