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 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 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), 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:
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:
An arrangement for metering a gaseous sample in a carrier gas stream has a sample gas path and a carrier gas path, both paths being connected to a carrier gas source. By introducing different pressures into the sample gas path and the carrier gas path, a metered amount is extracted from a sample slug and diverted into the carrier gas stream via a connection gas path through the carrier gas path. The sample gas path has two flow resistances in front of and behind a branch point of a connection gas path. One resistance lies between the carrier gas source and a metering unit and a gas volume of the sample gas path between the branch point of the connection gas path and the other flow resistance is dimensioned such that the sample slug only reaches the second resistance after extraction and diversion of the metered amount.
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 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:
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.
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.