Mobile device for analysing breath samples, comprising: - at least one mouthpiece provided with at least one inlet opening and at least one outlet opening for allowing a person to respectively inhale and exhale via the mouthpiece , - at least one analysis compartment connecting to the outlet opening of the mouthpiece , characterized by - at least one air filter connected to the mouthpiece for filtering ambient air to be inhaled by the person, - the at least one analysis compartment being provided with at least one chemical trace detector , wherein the chemical trace detector , comprises: o at least one semi-conducting sensor ; o at least one heating element for heating the semi-conducting sensor ; o at least one processor for controlling the heating element ; and o a detection circuit for detecting the change in resistance of the semi-conducting sensor which is at least partially determined by the presence of at least one chemical trace which reacts in the presence of the semi-conducting sensor , wherein the analysis compartment is provided with at least one outlet opening for discharging at least a part of the air exhaled into the device , wherein the chemical trace detector is positioned between an inlet opening of the analysis compartment connecting to the outlet opening of the mouthpiece and the outlet opening of the analysis compartment , whereby the exhaled air is blown along the at least one chemical trace detector . - at least one mouthpiece provided with at least one inlet opening and at least one outlet opening for allowing a person to respectively inhale and exhale via the mouthpiece , - at least one analysis compartment connecting to the outlet opening of the mouthpiece , characterized by - at least one air filter connected to the mouthpiece for filtering ambient air to be inhaled by the person, - the at least one analysis compartment being provided with at least one chemical trace detector , wherein the chemical trace detector , comprises: o at least one semi-conducting sensor ; o at least one heating element for heating the semi-conducting sensor ; o at least one processor for controlling the heating element ; and o a detection circuit for detecting the change in resistance of the semi-conducting sensor which is at least partially determined by the presence of at least one chemical trace which reacts in the presence of the semi-conducting sensor , wherein the analysis compartment is provided with at least one outlet opening for discharging at least a part of the air exhaled into the device , wherein the chemical trace detector is positioned between an inlet opening of the analysis compartment connecting to the outlet opening of the mouthpiece and the outlet opening of the analysis compartment , whereby the exhaled air is blown along the at least one chemical trace detector . o at least one semi-conducting sensor ; o at least one heating element for heating the semi-conducting sensor ; o at least one processor for controlling the heating element ; and o a detection circuit for detecting the change in resistance of the semi-conducting sensor which is at least partially determined by the presence of at least one chemical trace which reacts in the presence of the semi-conducting sensor , <EOS>