A method for modulating analytes in a gaseous stream passing through a capillary, wherein the analytes are retained in a trapping zone of the capillary, or allowed to pass therethrough, based on certain conditions. The method includes, during a first time period, heating the trapping zone of the capillary to a first temperature to desorb analytes therewithin and allow the analytes to pass therethrough, and during a second time period, cooling the capillary to a second temperature that is sufficient to trap and focus the analytes within the trapping zone. During the first time period, the method also includes retaining heat at the capillary during to minimize the load on a cooling device thermally connected thereto, and during the second time period, selectively allowing thermal transfer toward the cooling device.

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.

A method of performing a chromatographic separation includes generating a spatial temperature gradient along a length of a chromatographic column in a liquid chromatography system. A sample is injected into a flow of a mobile phase to the column and a flow of a mobile phase having a composition gradient is provided to the column after the sample is received at the column. The spatial temperature gradient is moved along the length of the column from the column inlet to the column outlet during the time that the composition gradient traverses the column. This coordination of the composition gradient with the movement of the spatial thermal gradient yields a significant increase in peak capacity per unit time compared with conventional separation techniques performed in a conventional isothermal column environment.

A miniaturized gas chromatography system integrated on single chip comprising a sample injection unit, a separation column having an inlet, an exit and an interior surface, at least one detector located at the separation column exit and the sample injection unit having a T-shaped configuration. The column may be coated with room temperature ionic liquids, with and without an intermediate layer between the room temperature ionic liquid and the silicon surface.

A system for performing gas chromatography analyzes in accordance with the present disclosure includes an analytical column and a column oven. The analytical column has an inlet portion coupled to an injector for receiving a material sample and an outlet portion coupled to a detector. The analytical column is adapted to direct the material sample from the injector to the detector. The column oven is adapted to heat the analytical column for separating constituent components of the material sample for detection by the detector.

Provided is a supercritical fluid device equipped with a back pressure regulator for creating a pressurized state in which a mobile phase in a separation/extraction unit of an analysis flow passage is kept in a supercritical fluid state. One end of a pipe is connected to an outlet side of the back pressure regulator, and the other end of the pipe is open to the atmosphere. A heating unit is provided on the pipe, and the heating unit includes a plurality of electrically independent heaters arranged on mutually different portions of the pile along the pipe. A power supply controller is connected to the heaters, and the power supply controller is configured to supply heating power to one or more heaters selected among the plurality of heaters, but to not supply heating power to the other heaters.

A heater assembly used in chromatography includes a thermally conductive base having a chamber extending fully through the base with an opening at a first side of the base and at a second side of the base, and a cavity with an opening at the second side of the base. A heater is disposed within the cavity in thermal communication with the base. A thermistor assembly, having a thermistor within a thermally conductive body is disposed within the chamber. The body has a head region with a planar surface. The planar surface of the head region is exposed at the opening of the chamber at the first side of the base for making thermally conductive contact therewith. The thermistor assembly is thermally isolated from the base.

A flexible, foldable light-weight gas chromatography transfer line suitable for connecting a gas chromatograph (GC) to a spectrometer, such as a mass spectrometer or optical spectrometer, in particular to the ion source of the spectrometer, such as an inductively coupled plasma (ICP) ion source. The transfer line has a heating arrangement that allows maintaining an even temperature profile, which improves quality of spectra. The transfer line has low thermal mass and the heating can be controlled with the control unit of the GC.

The disclosed apparatus includes a collision-type PM.sub.2.5 filter, a resistive heating rod with a temperature sensor, a sealed water tank, a condensation system, a virtual concentrator, a flow controller, a vacuum pump, a particulate matter collection bottle, dimethylacetamide reagent, an ultrasonic bath, a fraction automatic supply/collect integrated pump, a vacuum parallel concentrator, a micro-injection pump, and a liquid chromatography-time-of-flight mass spectrometer. This apparatus can replace traditional filter sampling for collecting PM.sub.2.5 greatly freeing up manpower, saving resources, and reducing organics loss in PM.sub.2.5. The collected sample solution is injected into the liquid chromatography-mass spectrometer for online analysis of organic components. By introducing an enrichment system, the concentration of sample PM.sub.2.5 can be increased at least by 10 times, enhancing the sampling capability of the apparatus. This apparatus achieves full automation of PM.sub.2.5 sampling and collection. This apparatus can be widely applied in air quality monitoring and health risk assessment.

The disclosure describes embodiments of an apparatus useful for the on-line analysis of gas and liquid samples including a gas compressor or pump, a sampling valve, a separation module, and one or more detectors. The detectors may include catalytic pellistors, thermal conductivity devices, or other sensors capable of detecting chemical substances in the presence of ambient air. These particular sensors in combination with reference elements allow direct use of ambient air as the carrier for analysis without pretreatment of the said air. Other embodiments are disclosed and claimed.