A method for controlling fraction collection of a target product in a column chromatography system including at least one affinity chromatography separation unit, the chromatography system being configured for cyclic purification performed on a sample comprising the target product, each cycle of the purification process including: - loading feed onto the separation unit, - washing the separation unit, and - eluting the target product from the separation unit by providing a flow of an elution fluid over the separation unit and controlling fraction collection by selectively directing a fraction of the outlet flow from the separation unit containing the eluted target product to a subsequent production step, wherein the method for controlling fraction collection of the target product comprises: registering the presence of the target product in the outlet flow from each column over time, determining trigger points for target product collection in relation to presence of target product in the outlet flow, the trigger points comprises a start time T1 and a stop time T2 for target product collection in relation to the start timepoint E of the elution phase for each cycle, and wherein the method for controlling fraction collection of target product further comprises: a) setting a first time period ΔC 0 based on the trigger points (31, 32) within which a fraction of the elution in the first cycle is captured; b) evaluating timing of the captured elution to identify trigger points (33, 34, 35, 36, 37, 38) and the corresponding next time period ΔC 1, ΔC 2, ΔC 3; c) applying the timing to capture and collect a fraction of the elution during the elution phase in the following cycle; d) repeating steps b) - c) during the purification process. - loading feed onto the separation unit, - washing the separation unit, and - eluting the target product from the separation unit by providing a flow of an elution fluid over the separation unit and controlling fraction collection by selectively directing a fraction of the outlet flow from the separation unit containing the eluted target product to a subsequent production step, registering the presence of the target product in the outlet flow from each column over time, determining trigger points for target product collection in relation to presence of target product in the outlet flow, the trigger points comprises a start time T1 and a stop time T2 for target product collection in relation to the start timepoint E of the elution phase for each cycle, and wherein the method for controlling fraction collection of target product further comprises: a) setting a first time period ΔC 0 based on the trigger points (31, 32) within which a fraction of the elution in the first cycle is captured; b) evaluating timing of the captured elution to identify trigger points (33, 34, 35, 36, 37, 38) and the corresponding next time period ΔC 1, ΔC 2, ΔC 3; c) applying the timing to capture and collect a fraction of the elution during the elution phase in the following cycle; d) repeating steps b) - c) during the purification process. a) setting a first time period ΔC 0 based on the trigger points (31, 32) within which a fraction of the elution in the first cycle is captured; b) evaluating timing of the captured elution to identify trigger points (33, 34, 35, 36, 37, 38) and the corresponding next time period ΔC 1, ΔC 2, ΔC 3; c) applying the timing to capture and collect a fraction of the elution during the elution phase in the following cycle; d) repeating steps b) - c) during the purification process.