Determining concentrations of components of a mixture

The invention relates to a system (100) to determine concentrations of components of a multiphase fluid, the system (100) comprising: a first flowmeter (108) configured to receive a fluid flow and to generate one or more measurements of the fluid flow, the fluid flow including a first liquid and a second liquid, wherein the first and second liquids are immiscible; a separation vessel (114) configured to receive the fluid flow, and to at least partially separate the first liquid and the second liquid; a second flowmeter (106) configured to receive either the second liquid or a mixture of the first liquid and the second liquid, through a valve and to generate one or more measurements of either the second liquid or the mixture of the first liquid and the second liquid, wherein a proportion of the second liquid to the first liquid in the mixture is greater than a proportion of the second liquid to the first liquid in the fluid flow; a third flowmeter (110) configured to receive the first liquid and to generate one or more measurements of the first liquid ; and a data processing apparatus (124) operatively coupled to the first flowmeter (108), the second flowmeter (106), the third flowmeter (110), the data processing apparatus (124) configured to perform operations comprising: receiving the one or more measurements of the fluid flow from the first flowmeter (108); receiving the one or more measurements of the second liquid or the mixture of the first liquid and the second liquid from the second flowmeter (106); receiving the one or more measurements of the first liquid from the third flowmeter (110), and determining a concentration of the second liquid in the fluid flow.