The invention relates to a heat flux sensor including: a heating wire (1) including a material capable of being taken to a determined temperature by Joule effect, suited to being connected to an electrical source, a resonator (2) of nano electro mechanical system (NEMS) type including: a beam (20) suspended with respect to a support (21), an actuating device (22) capable of generating a vibration of said beam under the effect of an excitation signal, a detection device configured to measure a displacement of said beam in the course of said vibration and to emit an output signal having a resonance at the resonance frequency of the resonator, said resonance frequency depending on the temperature of the beam,
wherein one end (20a) of the beam (20) is integral with the heating wire (1) so as to enable a conduction of heat from the heating wire to the beam, a variation in temperature of the heating wire induced by a variation in a characteristic of a fluid surrounding said wire causing a variation in the resonance frequency of the resonator.

A thermal conductivity detector includes a first pipe path that houses a filament, a second pipe path and a third pipe path that connects the first pipe path to the second pipe path. In the third pipe path, first, second and third gas lead-in portions are arranged in this order from the first pipe path toward the second pipe path. A carrier gas is led to the first and third gas lead-in portions alternately, and a sample gas is led to the second gas lead-in portion. The distance between the second and third gas lead-in portions is equal to or smaller than 1.3 times of a maximum dimension of an opening formed at the second gas lead-in portion. At least part of the third pipe path between the second gas lead-in portion and the third gas lead-in portion has a cross sectional area that is equal to or smaller than an area of the opening formed at the second gas lead-in portion.

A thermal conductivity detector includes a first pipe path that houses a filament, a second pipe path and a third pipe path that connects the first pipe path to the second pipe path. In the third pipe path, first, second and third gas lead-in portions are arranged in this order from the first pipe path toward the second pipe path. A carrier gas is led to the first and third gas lead-in portions alternately, and a sample gas is led to the second gas lead-in portion. The distance between the second and third gas lead-in portions is equal to or smaller than 1.3 times of a maximum dimension of an opening formed at the second gas lead-in portion. At least part of the third pipe path between the second gas lead-in portion and the third gas lead-in portion has a cross sectional area that is equal to or smaller than an area of the opening formed at the second gas lead-in portion.

A thermal conductivity detector includes: a first flow path (4) in which a filament (2) is arranged; a second flow path (6) provided separately from the first flow path (4); an introduction flow path (8) configured to fluidly communicate between an upstream of the first flow path (4) and an upstream end of the second flow path (6); a sample inlet (10) configured to introduce a sample gas to the introduction flow path (8); a first gas inlet (12) provided between the sample inlet (10) in the introduction flow path (8) and an upstream end of the first flow path (4); a second gas inlet (14) provided between the sample inlet (10) in the introduction flow path (8) and an upstream end of the second flow path (6); a carrier gas supply source (18); a selector (22) configured to selectively introduce the carrier gas from the carrier gas supply source (18) to one of the first gas inlet (12) and the second gas inlet (14); and a detection circuit (24) configured to detect a component in a sample gas via the filament (2), wherein when the carrier gas from the carrier gas supply source (18) is guided to the first gas inlet (12), a reference phase in which only the carrier gas flows through the first flow path (4) is formed, when the carrier gas from the carrier gas supply source (18) is guided to the second gas inlet (14), a sampling phase in which the sample gas flows through the first flow path (4) is formed, and wherein fluid resistance of the first flow path (4) and flow resistance of the second flow path (6) are designed such that a ratio of a difference between a reference flow rate and a sampling flow rate to each of the reference flow rate and the sampling flow rate becomes 15% or less, the reference flow rate being a flow rate of a gas flowing through the first flow path (4) in the reference phase, the sampling flow rate being a flow rate of gases flowing through the first flow path (4) in the sampling phase.

A thermal conductivity detector includes: a first flow path (4) in which a filament (2) is arranged; a second flow path (6) provided separately from the first flow path (4); an introduction flow path (8) configured to fluidly communicate between an upstream of the first flow path (4) and an upstream end of the second flow path (6); a sample inlet (10) configured to introduce a sample gas to the introduction flow path (8); a first gas inlet (12) provided between the sample inlet (10) in the introduction flow path (8) and an upstream end of the first flow path (4); a second gas inlet (14) provided between the sample inlet (10) in the introduction flow path (8) and an upstream end of the second flow path (6); a carrier gas supply source (18); a selector (22) configured to selectively introduce the carrier gas from the carrier gas supply source (18) to one of the first gas inlet (12) and the second gas inlet (14); and a detection circuit (24) configured to detect a component in a sample gas via the filament (2), wherein when the carrier gas from the carrier gas supply source (18) is guided to the first gas inlet (12), a reference phase in which only the carrier gas flows through the first flow path (4) is formed, when the carrier gas from the carrier gas supply source (18) is guided to the second gas inlet (14), a sampling phase in which the sample gas flows through the first flow path (4) is formed, and wherein fluid resistance of the first flow path (4) and flow resistance of the second flow path (6) are designed such that a ratio of a difference between a reference flow rate and a sampling flow rate to each of the reference flow rate and the sampling flow rate becomes 15% or less, the reference flow rate being a flow rate of a gas flowing through the first flow path (4) in the reference phase, the sampling flow rate being a flow rate of gases flowing through the first flow path (4) in the sampling phase.

A thermal conductivity detector includes a first pipe path that houses a filament, a second pipe path and a third pipe path that connects the first pipe path to the second pipe path. In the third pipe path, first, second and third gas lead-in portions are arranged in this order from the first pipe path toward the second pipe path. A carrier gas is led to the first and third gas lead-in portions alternately, and a sample gas is led to the second gas lead-in portion. The distance between the second and third gas lead-in portions is equal to or smaller than 1.3 times of a maximum dimension of an opening formed at the second gas lead-in portion. At least part of the third pipe path between the second gas lead-in portion and the third gas lead-in portion has a cross sectional area that is equal to or smaller than an area of the opening formed at the second gas lead-in portion.

A thermal conductivity detector includes a first pipe path that houses a filament, a second pipe path and a third pipe path that connects the first pipe path to the second pipe path. In the third pipe path, first, second and third gas lead-in portions are arranged in this order from the first pipe path toward the second pipe path. A carrier gas is led to the first and third gas lead-in portions alternately, and a sample gas is led to the second gas lead-in portion. The distance between the second and third gas lead-in portions is equal to or smaller than 1.3 times of a maximum dimension of an opening formed at the second gas lead-in portion. At least part of the third pipe path between the second gas lead-in portion and the third gas lead-in portion has a cross sectional area that is equal to or smaller than an area of the opening formed at the second gas lead-in portion.

A method for surface characterization of a porous solid or powder sample using flowing gas includes a controller that controls mass flow of a carrier gas and an adsorptive gas to form a mixture having a target concentration of the adsorptive gas over the sample, determining adsorptive gas concentration based on signals from a detector disposed downstream of the sample, automatically repeating the controlling and determining steps for a plurality of different target concentrations, and generating an isotherm for the sample based on the adsorptive gas concentration for the plurality of different target concentrations. The method may include immersing the sample in liquid nitrogen to cool the sample for all, or at least a portion of each of the different target concentrations. The target concentrations may vary from less than 5% to greater than 95%, and may vary in a stepwise manner.

A method for surface characterization of a porous solid or powder sample using flowing gas includes a controller that controls mass flow of a carrier gas and an adsorptive gas to form a mixture having a target concentration of the adsorptive gas over the sample, determining adsorptive gas concentration based on signals from a detector disposed downstream of the sample, automatically repeating the controlling and determining steps for a plurality of different target concentrations, and generating an isotherm for the sample based on the adsorptive gas concentration for the plurality of different target concentrations. The method may include immersing the sample in liquid nitrogen to cool the sample for all, or at least a portion of each of the different target concentrations. The target concentrations may vary from less than 5% to greater than 95%, and may vary in a stepwise manner.

A pretreatment method for analyzing dioxin compounds and an analytical method using the same, in which a column packed with polymer beads that are capable of selectively adsorbing dioxin compounds is used in a purification step during pretreatment, thereby remarkably reducing a time required for pretreatment and improving a recovery rate of an internal standard for purification, are provided.