A sample cell for IR spectrophotometric analysis of a liquid sample, the sample cell comprising: - two substantially parallel transparent plates enclosing a cavity for holding the liquid sample, - a liquid supply channel comprising a first part for pumping fresh liquid into the cavity and a second part for pumping liquid out of the cavity, - a thermally conductive material comprising a bypass channel for providing a bypass from the first part of the supply channel to the second part of the supply channel, and - a temperature control loop for controlling a temperature of the liquid sample in the cavity, the temperature control loop comprising: - at least one temperature sensor for measuring a temperature in or close to the cavity, - at least one heating element (12, 22, 32) for increasing a temperature of the liquid sample, and - control means, coupled to the temperature sensor and the heating element (12, 22, 32) for controlling the heating element (12, 22, 32) in dependence of the temperature in or close to the cavity, wherein - the heating element (12, 22, 32) comprises - a first heating foil (12, 32) which is attached to or thermally coupled to a first one of the transparent plates in such a way to allow an IR light beam to pass through the transparent plates and the cavity without being hindered by the heating foil (12, 32), wherein the first heating foil (12, 32) comprises the temperature sensor, and - a second heating foil which is attached to the thermally conductive material for heating the liquid in the bypass channel. - two substantially parallel transparent plates enclosing a cavity for holding the liquid sample, - a liquid supply channel comprising a first part for pumping fresh liquid into the cavity and a second part for pumping liquid out of the cavity, - a thermally conductive material comprising a bypass channel for providing a bypass from the first part of the supply channel to the second part of the supply channel, and - a temperature control loop for controlling a temperature of the liquid sample in the cavity, the temperature control loop comprising: - at least one temperature sensor for measuring a temperature in or close to the cavity, - at least one heating element (12, 22, 32) for increasing a temperature of the liquid sample, and - control means, coupled to the temperature sensor and the heating element (12, 22, 32) for controlling the heating element (12, 22, 32) in dependence of the temperature in or close to the cavity, wherein - the heating element (12, 22, 32) comprises - a first heating foil (12, 32) which is attached to or thermally coupled to a first one of the transparent plates in such a way to allow an IR light beam to pass through the transparent plates and the cavity without being hindered by the heating foil (12, 32), wherein the first heating foil (12, 32) comprises the temperature sensor, and - a second heating foil which is attached to the thermally conductive material for heating the liquid in the bypass channel. - at least one temperature sensor for measuring a temperature in or close to the cavity, - at least one heating element (12, 22, 32) for increasing a temperature of the liquid sample, and - control means, coupled to the temperature sensor and the heating element (12, 22, 32) for controlling the heating element (12, 22, 32) in dependence of the temperature in or close to the cavity, wherein - the heating element (12, 22, 32) comprises - a first heating foil (12, 32) which is attached to or thermally coupled to a first one of the transparent plates in such a way to allow an IR light beam to pass through the transparent plates and the cavity without being hindered by the heating foil (12, 32), wherein the first heating foil (12, 32) comprises the temperature sensor, and - a second heating foil which is attached to the thermally conductive material for heating the liquid in the bypass channel. - a first heating foil (12, 32) which is attached to or thermally coupled to a first one of the transparent plates in such a way to allow an IR light beam to pass through the transparent plates and the cavity without being hindered by the heating foil (12, 32), wherein the first heating foil (12, 32) comprises the temperature sensor, and - a second heating foil which is attached to the thermally conductive material for heating the liquid in the bypass channel.