The invention relates to a device for determining a volume of liquid in a hydrocarbon fluid sample, the device including: a cell (1) comprising an upper part (3) defined by a tubular sidewall (5) and a lower part (4) defined by a closed extremity, the lower part having a conical shape and forming a chamber (12) configured to receive the liquid; and a piston (2) comprising an upper part (15) and a lower part (16), the piston being slidable in the cell and sealing the cell in a gas-tight manner. The invention also relates to a method for determining a volume of liquid in a hydrocarbon fluid sample.