The invention concerns a method for quantitative or qualitative determination of an analyte or its interaction or reaction kinetics in a system with at least two different phases, comprising the step of taking at least one measurement signal from at least one of the phases, whereby the different phases are present in parallel when taking the signal and whereby each measurement signal is attributed to one of at least two phases. In addition, the invention concerns a sample carrier, in particular for use in the method constituting the invention with one or more wells. The sample carrier is characterized by the fact that at least a portion of the sample carrier at least in the range of one or more wells is coated with fluorescence-quenching material.