A method for determining a sample flow volume is disclosed herein. The method includes withdrawing the sample flow at a first and second flow rate from a gas flow, measuring a concentration of at least one gas component and measuring at least one of an airway pressure and flow. The method also includes generating first measurement results based on the concentration, generating second measurement results based on the at least one of the airway pressure and flow and setting a suitable point of comparison. The method further includes determining a first and second time delay between the point of comparison of the first and second measurement results of the first and second flow rate, providing information about the first and second sample flow rate and determining the sample volume based on differences between the first and second time delay. A corresponding arrangement is also provided.
