Systems, apparatus and methods determine the presence of a volatile substance in expired breath. Alcohol concentrations can be determined from expired breath through the use of electromagnetic detection. The systems, apparatus and methods allow measurements of volatile substances to be done accurately and quickly over a wide range of temperatures, and are easily incorporated into vehicles.

A sensor system that removes responses from an interferent and/or corrects for baseline drift of a sensor to determine a presence, a concentration or a change in concentration of a target material in a gaseous environment. Fluid flowing into the system may be directed by a valve arrangement to either a first fluid flow path or a second fluid flow path. The target material may be absorbed by a filter material in the first fluid flow path. Fluid flowing along the second gas flow path passes directly to the sensor. Responses of the sensor to fluids from the first and second fluid flow paths may be used to determine a presence, concentration or change in concentration of the target material.

A gas analysis system and method using a spectrometer, such as a Fourier transform infrared spectrometer, utilizes a reactor, such as a catalytic reactor, for providing interference spectra. The gas is pressurized and chilled to remove water prior to the spectrometer.

Provided is a system for detection and discrimination of gases, such as volatile organic compounds (VOCs), in a sample comprising two chambers, a first chamber equipped with a crystalline microporous material (CMM) and a second chamber equipped with a gas detector. A gas sample is introduced first into the second chamber for detection by the gas detector and is then re-routed to the first chamber for adsorption/desorption on the CMM. The gas detector in the second chamber produces electronic signals that correspond to the adsorption/desorption profile for the gas, which allows for discrimination of the gas in the sample from other possible gas samples.

Methods and systems for detecting and limiting the water in a photoionization detector are provided. The method may include powering off a lamp configured to ionize particles of air. The method may also include monitoring a signal from the photoionization detector. The signal may be monitored based on a current between a signal electrode and a bias electrode. In an instance the signal is above a signal threshold, the method may also include electrolyzing one or more particles of water present in the photoionization detector by closing a leakage switch in order to allow current to flow through the bias electrode and the signal electrode. In an instance the signal is below the signal threshold, the method may include powering on the lamp to begin photoionization detection. Corresponding systems are also provided.

In an analysis of a fluid component using a nanomechanical sensor covered with a receptor, the same receptor is caused to express different response characteristics. In a measuring system of analyzing a response when a sample gas and a purge gas are supplied to a nanomechanical sensor while switching the sample gas and the purge gas, a gas (external gas) different from both gases is mixed into a gas channel and supplied to the sensor for measurement. Since a response characteristic of a receptor is modulated by mixing of the external gas, the object described above is achieved.

A gas sensor apparatus (100) comprising a gas inlet (10); a first gas sensor (40); a first gas flow path between the inlet and the gas sensor; a humidifier (20) disposed between the gas inlet and the gas sensor in the first gas flow path of the gas sensor apparatus; and a dehumidifier (30) disposed between the humidifier and the first gas sensor in the first gas flow path. The gas sensor apparatus may have more than one gas flow path. The gas sensor apparatus may contain more than one sensor. The gas sensor apparatus may contain one or more filters for filtering a target gas or a non-target gas. The gas sensor apparatus may be used in detection of ethylene and/or 1-methylcyclopropene.

A method for characterizing compounds of interest, introduced into a measuring chamber of an electronic nose, includes injecting a first gas sample formed from a carrier gas without the compounds of interest forming a second gas sample from the carrier gas with the compounds of interest; determining a measurement signal (S.sub.k(t.sub.i)); measuring values φ1, φ2 of the relative humidity; determining corrective parameter ({tilde over (S)}.sub.k.sup.ref|.sub.φ2; ΔS.sub.k.sup.ref|.sub.Δφ); and determining a useful signal (Su.sub.k(t.sub.iϵP2)) by correcting the measurement signal associated with the second gas sample using the determined corrective parameter, and characterizing the compounds of interest based on the useful signal.

The present invention suppresses an adverse effect caused when an additional gas such as water vapor is mixed in a sample gas or the like that is subjected to gas measurement. In an embodiment of the present invention, in gas measurement for analyzing sensor output signals obtained by alternately supplying a sample gas and a reference gas to a sensor element while alternately switching between the sample gas and the reference gas, the sample gas and the reference gas pass through a humidity equilibration device partitioned by a water vapor permeable membrane, and then are supplied to the sensor element. As a result, since both gases have substantially the same value of humidity at the time of being supplied to the sensor element, influences of water vapor are substantially cancelled out in signals output from the sensor element by the alternate supply of the sample gas and the reference gas.

A remote test apparatus is configured to simulate an environment of at least one remotely located room and configured to receive at least one air sample from the at least one remotely located room. The apparatus includes a sealed enclosure forming an interior cavity and including an inlet in connection with the at least one remotely located room and an outlet in connection with a sample collection unit. The sample collection unit is configured to communicate the at least one air sample from the remotely located room at a first flow rate. The apparatus further includes at least one sensor disposed in the interior cavity and at least one air transfer unit configured to transfer test air from the interior cavity of the sealed enclosure to the at least one sensor at a second flow rate.