Abstract: A multi-way valve has an upper part, a lower part and a central part connected to the upper part via an interposing first membrane and the lower part via an interposing second membrane, wherein the upper and lower parts contain recesses on the upper and lower part faces facing the membranes, where a control fluid is introducible into the recesses, the central part contains a pair of openings in regions opposite the recesses on the central part faces lying adjacent to the membranes, where while introducing the control fluid into a recess, the membrane closes respective opposite openings in the central part, and where the membrane otherwise recedes into the recess, thereby releasing the opposite openings, where valve connections are mounted on the upper or lower part such that the central part can have a very thin design while preventing dead regions in the channel systems.

Abstract: A thermal conductivity detector includes a heatable resistive detector configured to be physically arranged in an analytes flow eluting from a chromatography column and electrically arranged with resistors in separate arms of a measuring bridge, an amplifier which detects differential voltage between two opposite nodes of the bridge and applies an output voltage to other opposite nodes of the measuring bridge to maintain the detector at a constant operating temperature, and an additional resistor with a controllable switch in parallel connected in series with the detector or resistor arranged in one arm of the bridge, where the switch is periodically turned on and off at a predetermined duty cycle and/or controlled by information on characteristic times-of-arrival of analytes at the detector to compensate for operating temperature uncertainties due to manufacturing variations of the resistors and/or to allow for processing small and large peaks of a chromatogram with highest available resolution.

Abstract: A thermal conductivity detector for a gas chromatograph includes a heatable resistive detector element configured to be physically arranged in a flow of analytes eluting from a chromatography column and electrically arranged together with resistors in separate arms of a measuring bridge, wherein to provide a new configuration of the thermal conductivity detector to allow high detector sensitivity and to meet intrinsic safety requirements, the detector element includes at least two equal detector sub-elements that are configured to be physically arranged in series in the flow of analytes and electrically arranged in parallel with each other, where the detector element in one arm and a reference resistor in the other arm of the same half of the measuring bridge are configured such that the total resistance of the parallel detector sub-elements at operating temperature is at least approximately equal to the resistance of the reference resistor.

Abstract: A multi-way valve has an upper part, a lower part and a central part connected to the upper part via an interposing first membrane and the lower part via an interposing second membrane, wherein the upper and lower parts contain recesses on the upper and lower part faces facing the membranes, where a control fluid is introducible into the recesses, the central part contains a pair of openings in regions opposite the recesses on the central part faces lying adjacent to the membranes, where while introducing the control fluid into a recess, the membrane closes respective opposite openings in the central part, and where the membrane otherwise recedes into the recess, thereby releasing the opposite openings, where valve connections are mounted on the upper or lower part such that the central part can have a very thin design while preventing dead regions in the channel systems.

Abstract: A thermal conductivity detector includes a switch controllable to short-circuit the input of an amplifier to improve the thermal conductivity detector for use in gas chromatography without the need of an additional reference cell, wherein a digital signal processor calculates a transfer function of an analog signal processor from a digitized difference signal received in response to short-circuiting the input of the amplifier at a given time when solely a reference carrier fluid passes through a measuring cell, and the digital signal processor recovers a detector signal by deconvoluting the digitized difference signal with a transfer function.

Abstract: A modulator for simply providing fast and precise sampling of a chromatographic peak eluting from a first column into a second column of a comprehensive two-dimensional gas chromatograph, where the modulator includes a planar component containing a first gas passage for connecting a carrier gas source to the second separation column, a second gas passage for connecting the first separation column to an exhaust outlet, a connecting gas passage between the first and second gas passages, and two individually controllable open/close valves arranged in parallel connection in the first gas passage between its connection to the carrier gas source and the branch-off of the connecting gas passage, and where the gas passages and valves are formed in the planar component by micromachining.

Abstract: A thermal conductivity detector which includes a measurement channel, an electrically heatable heating filament extending longitudinally along the center of the measurement channel so that a fluid passing through the measurement channel flows around the filament, an evaluator that detects electrical resistance changes of the heating filament and provide an output representative of the presence and amount of various fluid components passing the heating filament, and a bypass channel for bypassing the measurement channel, where the bypass channel has a lower fluidic resistance than the measurement channel and where, in order to improve the detection capability, the thermal conductivity detector further includes a flow sensor for measuring the flow of the fluid in the bypass channel and for providing an output indicative of the measured flow, and a correcting device for correcting the output of the evaluator using the output of the flow sensor.

Abstract: A thermal conductivity detector includes at least four detector components that are arranged in receptacles of a thermal conduction block in a circle around a center axis of the thermal conduction block. The thermal conduction block comprises a central portion along the axis, the cross-axial dimensions of the central portion being less than the diameter of the circle. There are at least four equal peripheral portions that are connected solely to the central portion and are separated from each other, each of the peripheral portions carrying one of the detector components.

Abstract: A thermal conductivity detector with a bar which is arranged in the center and in the longitudinal direction of a channel such that it can be flowed around by a fluid and is supported unilaterally on a support traversing the channel, which has a support arm on each of the two sides of the connection with the bar, wherein the bar and the support are made of doped silicon and on one side, under an intermediate layer of an insulating layer, have a metal layer which is interrupted in one region of one of the support arms and is in contact there with the doped silicon through the insulating layer on the side next to the support arm and at the free end of the bar respectively.

Abstract: A thermal conductivity detector for a gas chromatograph includes a heatable resistive detector element configured to be physically arranged in a flow of analytes eluting from a chromatography column and electrically arranged together with resistors in separate arms of a measuring bridge, wherein to provide a new configuration of the thermal conductivity detector to allow high detector sensitivity and to meet intrinsic safety requirements, the detector element includes at least two equal detector sub-elements that are configured to be physically arranged in series in the flow of analytes and electrically arranged in parallel with each other, where the detector element in one arm and a reference resistor in the other arm of the same half of the measuring bridge are configured such that the total resistance of the parallel detector sub-elements at operating temperature is at least approximately equal to the resistance of the reference resistor.

Abstract: A thermal conductivity detector includes a heatable resistive detector configured to be physically arranged in an analytes flow eluting from a chromatography column and electrically arranged with resistors in separate arms of a measuring bridge, an amplifier which detects differential voltage between two opposite nodes of the bridge and applies an output voltage to other opposite nodes of the measuring bridge to maintain the detector at a constant operating temperature, and an additional resistor with a controllable switch in parallel connected in series with the detector or resistor arranged in one arm of the bridge, where the switch is periodically turned on and off at a predetermined duty cycle and/or controlled by information on characteristic times-of-arrival of analytes at the detector to compensate for operating temperature uncertainties due to manufacturing variations of the resistors and/or to allow for processing small and large peaks of a chromatogram with highest available resolution.

Abstract: A method for improving the chromatographic detection limit for an analyte including a) producing a chromatogram with a peak of the analyte, b) calculating a regression straight line for a baseline from measured values of a section without a peak in the chromatogram, c) calculating a regression function from measured values of the peak of the analyte, d) subtracting the regression function from the chromatogram, e) calculating a regression polynomial for the baseline from the values of the chromatogram which have been changed in step d), f) calculating a further regression function from the measured values of the peak in the produced chromatogram, g) calculating a peak area between the regression polynomial and the further regression function, h) repetition of step d) with the further regression function instead of the regression function and of steps e), f) and g), until the calculated peak area changes by less than a predetermined amount.

Abstract: A thermal conductivity detector includes a switch controllable to short-circuit the input of an amplifier to improve the thermal conductivity detector for use in gas chromatography without the need of an additional reference cell, wherein a digital signal processor calculates a transfer function of an analog signal processor from a digitized difference signal received in response to short-circuiting the input of the amplifier at a given time when solely a reference carrier fluid passes through a measuring cell, and the digital signal processor recovers a detector signal by deconvoluting the digitized difference signal with a transfer function.

Abstract: The invention relates to a gas sample to be analyzed, wherein said sample is guided by means of a carrier gas through a separator unit having a downstream thermal conductivity detector providing a chromatogram having peaks for different analytes as a measurement signal. When using a thermal conductivity detector having a heated gold thread coated with a parylene F, hydrogen is used as a carrier gas, and a peak for the analyte hydrogen sulfide is generated by differentiating the chromatogram at the location of said analyte. The invention permits unlimited use of hydrogen as a carrier gas, even if the analyte is oxygen.

Abstract: A thermal conductivity detector includes at least four detector components that are arranged in receptacles of a thermal conduction block in a circle around a center axis of the thermal conduction block. The thermal conduction block comprises a central portion along the axis, the cross-axial dimensions of the central portion being less than the diameter of the circle. There are at least four equal peripheral portions that are connected solely to the central portion and are separated from each other, each of the peripheral portions carrying one of the detector components.

Abstract: A liquid-metering device comprising a droplet generator including a reservoir and, connected to the latter, a displacement space which is modifiable by an electromechanical transducer and which has an outlet opening and, upon excitation of the transducer, shoots a liquid droplet from a cold area into a heatable area through or counter to a gas stream generated by a gas source. To make the device suitable for automatic and quasi-continuous liquid metering in process analysis, a heatable evaporation chamber is provided through which the liquid to be metered flows via valves, and, between the evaporation chamber and the reservoir, a condensate chamber is connected via further valves. The condensate chamber and the reservoir are connected via additional valves and a pressure regulator to the gas source.

Abstract: A modulator for simply providing fast and precise sampling of a chromatographic peak eluting from a first column into a second column of a comprehensive two-dimensional gas chromatograph, where the modulator includes a planar component containing a first gas passage for connecting a carrier gas source to the second separation column, a second gas passage for connecting the first separation column to an exhaust outlet, a connecting gas passage between the first and second gas passages, and two individually controllable open/close valves arranged in parallel connection in the first gas passage between its connection to the carrier gas source and the branch-off of the connecting gas passage, and where the gas passages and valves are formed in the planar component by micromachining.

Abstract: A liquid-metering device comprising a droplet generator including a reservoir and, connected to the latter, a displacement space which is modifiable by an electromechanical transducer and which has an outlet opening and, upon excitation of the transducer, shoots a liquid droplet from a cold area into a heatable area through or counter to a gas stream generated by a gas source. To make the device suitable for automatic and quasi-continuous liquid metering in process analysis, a heatable evaporation chamber is provided through which the liquid to be metered flows via valves, and, between the evaporation chamber and the reservoir, a condensate chamber is connected via further valves. The condensate chamber and the reservoir are connected via additional valves and a pressure regulator to the gas source.

Abstract: The invention relates to a gas sample to be analyzed, wherein said sample is guided by means of a carrier gas through a separator unit having a downstream thermal conductivity detector providing a chromatogram having peaks for different analytes as a measurement signal. When using a thermal conductivity detector having a heated gold thread coated with a parylene F, hydrogen is used as a carrier gas, and a peak for the analyte hydrogen sulfide is generated by differentiating the chromatogram at the location of said analyte. The invention permits unlimited use of hydrogen as a carrier gas, even if the analyte is oxygen.

Abstract: A gas chromatograph for analyzing natural gas, with a first separation column (6). A first detector (7) is provided following the first separation column, the first separation column and the first detector operable to separate or detect propane and higher hydrocarbons. A second separation column (8) and a second detector (9) following it are provided to separate or detect carbon dioxide and ethane. A third separation column (10) and a third detector (11) following it are provided to separate or detect nitrogen and methane. A controllable changeover device (12) is provided between the second separation column (8) and the third separation column (10) to discharge eluates following methane. The first, second and third separation columns (6, 8, 10) and the first, second and third detectors (7, 9, 11) are connected in series. At least the first and the second detectors (7, 9) are operable to detect a mixture of substances flowing through them in a non-destructive manner.