System and method for analysing volatile organic compounds (VOC) by low-temperature plasma and mass spectrometry (LTP-MS)

1 . A system for analyzing volatile organic compounds (VOCs) that have been collected by contact sampling on an adsorbent interface membrane, by low-temperature plasma and mass spectrometry (LTP-MS), comprising:

an adsorbent interface membrane permeable to VOCs, having a first face and a second face, said adsorbent interface membrane configured to ensure controlled diffusion of the VOCs from the first face to the second face:

a receptacle for receiving the adsorbent interface membrane, the receptacle positioning the adsorbent interface membrane such that the first face is contactable with a VOC source for sampling;

a low-temperature plasma ionizer configured to emit a plasma stream in a plasma emission direction, ionizing the VOCs adsorbed by the adsorbent interface membrane to diffuse the VOCs to the second face of the adsorbent interface membrane to form an ionized gas laden with VOCs; and

a mass spectrometer configured to analyze the ionized gas laden with VOCs.

2 . The system according to claim 1 , further comprising a heater for heating the adsorbent interface membrane.

3 . The system according to claim 1 , wherein the receptacle is positioned outside the plasma stream and wherein:

the receptacle is a container that is resealable so as to form a sealed environment except for an inlet and an outlet;

the container comprises a carrier gas inlet for the entry of a carrier gas into the container and a gas outlet for the exit of a gas potentially laden with VOCs.

4 . The system according to claim 3 , further comprising:

a carrier gas injection tube extending along a gas injection axis and of which one end, the outlet end, opens into the closed container, the closed container being configured to hold the adsorbent interface membrane so that its surface is perpendicular to the gas injection axis, thereby enabling the carrier gas to become laden with VOCs as it passes through the adsorbent interface membrane; and

a guide tube for conveying the VOC-laden carrier gas to the ionizer.

5 . The system according to claim 4 , wherein the closed container comprises a membrane support for supporting the adsorbent interface membrane, a sampling inlet for the entry of a sample gas and the loading of the adsorbent interface membrane with VOCs, a sampling outlet for the exit of the sample gas, a carrier gas inlet.

6 . The system according to claim 5 , wherein the membrane support is a membrane magazine configured to be moved in rotation and/or translation and comprising a plurality of membrane housing compartments, the membrane magazine being mounted so as to place a single housing compartment, the housing compartment under analysis, opposite the outlet end of the injection tube and the inlet end of the guide tube.

7 . The system according to claim 4 , further comprising a guide tube and wherein:

the container outlet is extended by the guide tube, the free end of the tube being close to the plasma stream when said stream is emitted so that the plasma ionizes the laden gas at the tube outlet.

8 . The system according to claim 3 , further comprising a connector with at least two arms, and wherein:

a first arm is connected to the outlet of the container;

a second arm has one end directed towards the inlet of the mass spectrometer;

the ionizer is configured so that the plasma stream is directed towards an opening between the first and second arm or a third arm during operation.

9 . The system according to claim 1 , wherein the receptacle is arranged under the plasma stream such that the plasma stream is directed towards the adsorbent interface membrane when the adsorbent interface membrane is received in the receptacle.

10 . The system according to claim 9 , wherein:

the receptacle is a container that is resealable so as to form a sealed environment except for inlets and an outlet;

the container comprises a carrier gas inlet for the entry of a carrier gas into the container, a gas outlet for the exit of the ionized gas, and a plasma inlet;

the outlet is extended by a guide tube for guiding the ionized gas towards the inlet of the mass spectrometer.

11 . The system according to claim 1 , wherein the ionizer is an ionizer with one electrode or two electrodes.

12 . A method for analyzing VOCs adsorbed on an adsorbent interface membrane, by LTP-MS, using the system according to claim 1 , the method comprising:

providing an adsorbent interface membrane on which VOCs have been adsorbed;

desorbing the VOCs adsorbed on the adsorbent membrane;

low-temperature plasma ionizing the desorbed VOCs, thereby forming an ionized gas; and

analyzing the ionized gas, by mass spectrometry.

13 . The method according to claim 12 , wherein analyzing comprises comparing the obtained spectra with a database of molecular fingerprints.

14 . The method according to claim 13 , wherein VOCs from a patient have been adsorbed on the adsorbent interface membrane, the method further comprising determining the patient's medical status based on the results of the comparison.

15 . The method according to claim 14 , wherein the patient's medical status includes information concerning at least one among the stage, grade, and type of breast cancer.

16 . A method for diagnostic aid, in particular for breast cancer, comprising the method according to claim 13 , wherein VOCs from the patient have been adsorbed on the adsorbent interface membrane, the method further comprising determining the patient's medical status based on the results of the comparison.

17 . The method according to claim 16 , wherein the patient's medical status includes information concerning at least one among the stage, grade, and type of breast cancer.