Device for testing a sample via a gas stream, comprising: - an opening, - means for generating a gas stream in the device along at least one flow path passing through the opening, - at least one pressure sensor (5, 6), each pressure sensor being arranged in order to measure a pressure of the gas stream along at least one flow path, and - a mass flowmeter, arranged in order to measure a parameter representing the mass flow rate of the gas stream along each flow path, characterized in that: - the at least one flow path comprises a suction path starting at the opening, - the means for generating the gas stream are arranged in order to suck in a gas to be analyzed so that this gas to be analyzed flows along the suction path, - within the device, said suction path narrows locally at a measurement hole, - the at least one pressure sensor comprises a suction pressure sensor arranged in order to measure a pressure of the gas to be analyzed along the suction path, - the mass flowmeter is arranged in order to measure a parameter representing the mass flow rate of the gas to be analyzed along the suction path, and - the device also comprises calculation means arranged in order to quantify the presence of a gas of interest within the gas to be analyzed, based on a measurement of the parameter representing the mass flow rate of the gas to be analyzed along the suction path, and characterized in that the calculation means are arranged in order to quantify the presence of the gas of interest in the form of a calculation of a _proportion or of a volume of the gas of interest which depends on the diameter of the measurement hole. - an opening, - means for generating a gas stream in the device along at least one flow path passing through the opening, - at least one pressure sensor (5, 6), each pressure sensor being arranged in order to measure a pressure of the gas stream along at least one flow path, and - a mass flowmeter, arranged in order to measure a parameter representing the mass flow rate of the gas stream along each flow path, - the at least one flow path comprises a suction path starting at the opening, - the means for generating the gas stream are arranged in order to suck in a gas to be analyzed so that this gas to be analyzed flows along the suction path, - within the device, said suction path narrows locally at a measurement hole, - the at least one pressure sensor comprises a suction pressure sensor arranged in order to measure a pressure of the gas to be analyzed along the suction path, - the mass flowmeter is arranged in order to measure a parameter representing the mass flow rate of the gas to be analyzed along the suction path, and - the device also comprises calculation means arranged in order to quantify the presence of a gas of interest within the gas to be analyzed, based on a measurement of the parameter representing the mass flow rate of the gas to be analyzed along the suction path, and characterized in that the calculation means are arranged in order to quantify the presence of the gas of interest in the form of a calculation of a _proportion or of a volume of the gas of interest which depends on the diameter of the measurement hole.