Abstract: A reference measurement apparatus for a multiphase flow meter comprising: a sampling and measuring chamber coupled to a sampling port via a sample transfer line for extracting the sample having at least one of the gas phase and the liquid phase from the multiphase fluid mixture flowing through the pipe section; a pressure and temperature regulation arrangement arranged to maintain the sample from the sampling port to the sampling and measuring chamber at a pressure/temperature substantially similar to the pressure/temperature of the multiphase fluid mixture flowing through the pipe section; and a second fraction measurement device arranged to estimate a linear attenuation related to the at least one of the gas phase and the liquid phase extracted from the sample, said linear attenuation being used to correct the estimated representative fraction for the at least one of the gas phase and the liquid phase of the multiphase fluid mixture.