A gas chromatograph is provided with: a sample gas generator (2) configured to generate a sample gas from an injected sample; a separation column (6) fluidly connected to an outlet of the sample gas generator, the separation column (6) being configured to separate components in the sample gas generated by the sample gas generator (2); a detector (8) fluidly connected to an outlet of the separation column (6), the detector (8) being configured to detect the components separated in the separation column (6); a plurality of gas supply sources (12A, 12B) each configured to supply a carrier gas for carrying the sample gas generated by the sample gas generator to the separation column (6); a switching unit (12A, 12B) fluidly connected to the plurality of gas supply sources, the switching unit being configured to switch such that one of the plurality of gas supply sources is fluidly connected to the sample gas generator (2); a regulator (16) interposed between the switching unit (14) and the sample gas generator (2), the regulator (16) being configured to regulate a gas supply pressure from the gas supply source (12A, 12B) and a gas supply flow rate to the sample gas generator (2); and a control unit (30) configured to control an operation of the regulator (16), wherein the control unit (30) is configured such that in a case where the gas supply source fluidly connected to the sample gas generation unit has been changed in order to shift to a standby state capable of performing subsequent sample analysis and that at least a gas type of the carrier gas supplied to the supply gas generation unit (2) has been changed, the control unit (30) performs a replacement promotion operation for putting the gas supply pressure, the gas supply flow rate, or a combination thereof to a state different from the standby state to promote a gas replacement in the flow path for the carrier gas.

A gas chromatograph is provided with: a sample gas generator; a separation column; a detector; a plurality of gas supply sources; a switching unit; a regulator-; and an out-of-gas determination unit. After the out of gas determination unit has determined that the out of gas has occurred in the gas supply source supplying the carrier gas to the sample gas generator, it is configured to perform a column protection operation for changing the gas supply source fluidly connected to the sample gas generator by the switching unit.

A gas sampler includes a connection portion connectable to an introduction piping connected to a sample tank, a switching valve for switching a connection state between the connection portion and a sample loop, a pump, and a control device. A buffer flow path between the sample loop and the pump is configured to be selectively connectable to any one of a plurality of buffer tanks different in volume. A volume of the buffer flow path is greater than a volume of the introduction piping by a predetermined amount. The control device operates the pump in a state in which the switching valve is in a closed state to set an inside of the buffer flow path to a negative pressure, and thereafter stops the pump and make the switching valve in an open state to fill the sample loop with a sample gas by using the negative pressure of the buffer flow path.

A multi-dimensional liquid analysis system includes a flow splitter for separating mobile phase outflow from a first dimension liquid analysis system into first and second liquid split outlet flows. Volumetric flow rate control of the split outlet flows is provided by a flow control pump which withdraws one of the split outlet flows from the flow splitter at a controlled withdrawal flow rate to define the other split outlet flow rate as the difference between the outflow rate from the first dimension system and the withdrawal flow rate. In this manner, accurate and consistent flow division can be accomplished, which is particularly useful for multi-dimensional liquid analysis.

When a liquid in the column is replaced by carbon dioxide in a supercritical state in the chromatograph, an operation of a first pump is controlled by a flow rate control unit, and the carbon dioxide in the supercritical state is supplied at a constant pressure. Moreover, when a flow rate of the carbon dioxide in the supercritical state reaches a predetermined flow rate thereafter, the flow rate control unit controls an operation of the first pump so that the carbon dioxide in the supercritical state is supplied at a constant flow rate.

When a liquid in the column is replaced by carbon dioxide in a supercritical state in the chromatograph, an operation of a first pump is controlled by a flow rate control unit, and the carbon dioxide in the supercritical state is supplied at a constant pressure. Moreover, when a flow rate of the carbon dioxide in the supercritical state reaches a predetermined flow rate thereafter, the flow rate control unit controls an operation of the first pump so that the carbon dioxide in the supercritical state is supplied at a constant flow rate.

Pressure-controlled splitting can be used to inject a chemical sample from an injection source to a detector (e.g., a mass spectrometer) for chemical analysis (e.g., gas chromatography or gas chromatography-mass spectrometry) with reduced peak widths. For example, the sample is first transferred to a first compression volume; then pressure in the system is increased to compress the sample to split it between a second compression volume and a column. The fraction of the sample split to the column can have reduced peak widths compared to the peak widths prior to compression and splitting yet can maintain the same peak height to preserve high sensitivity for trace level analysis. This portion of the sample can traverse the column and elute to the detector for analysis with reduced chemical noise. Faster injection rates can allow faster analysis times, as less separation of chemicals is needed before the sample reaches the detector.

Disclosed is a method for determining an operating flow rate for a chromatographic column (4) in an HPLC system (1). The method comprises: measuring/calculating a pressure of the system (1) without the chromatographic column (4) for one or more flow rates; fitting a function to the flow rate(s) and corresponding pressure(s), calculating from the function and a predetermined recommended flow rate for the chromatographic column (4) a system pressure drop at the predetermined recommended flow rate. An operating flow rate is determined by summing the system pressure drop and a maximal column pressure limit, and determining a contribution of the system pressure drop to the summed pressure. If this contribution exceeds 1% an operating flow rate for the column is determined to a flow rate that corresponds to a pressure at a pressure monitor arranged before the column that is lower than the predetermined maximum column pressure limit.

Systems for use with liquid chromatography for provision of continuous flow or gradient flow in connection with two pumps providing mobile phase to a valve.

An analysis assistance method includes setting pressure in a first BPR to a value higher than a prescribed second set value with pressure in a second BPR set to a second set value, instructing a supercritical fluid chromatograph to supply a mobile phase to a supply flow path at a flow rate of the mobile phase that is to be theoretically supplied to a first flow path when the mobile phase is supplied to the supply flow path at a prescribed total flow rate and a prescribed sample introduction ratio, and gradually decreasing a set value of the pressure in the first BPR, and detecting a set value of the pressure in the first BPR at the time when supply of the mobile phase to a second flow path is stopped due to a decrease in set value of the pressure in the first BPR, as a first set value.