An electrochemiluminescence method of detecting an analyte in a liquid sample and a corresponding analysis system. An analyte in a liquid sample is detected by first providing a receptacle containing a fluid comprising protein coated magnetic microparticles to a stirring unit. Stirring of the fluid is necessary since the density of the microparticles is usually higher than the density of the buffer fluid. Thus the microparticles tend to deposit on the bottom of the receptacle leading to an aggregation of the microparticles because of weak interactions. To obtain representative measurements a homogeneous distribution of the microparticles in the buffer fluid is necessary to ensure a constant concentration of microparticles for each analysis cycle. It is further necessary to provide disaggregation of the microparticles, which is also realized by stirring the fluid. Stirring is conducted with a rotational frequency that is adapted to the amount of fluid to be stirred.