A method and system for determining the dissociation constant (K.sub.d) of a reversible binding pair of a first compound and a second compound. The method comprises: injecting a sample into a capillary tube via one or more valves, wherein the sample comprises the first compound, the second compound, and a first compound-second compound complex; injecting a mobile phase into the capillary tube via said one or more valves, the sample flowing through the capillary tube under laminar flow conditions, wherein the second compound and the first compound-second compound complex is separated from the first compound by transverse diffusion; measuring time dependence of a signal that is proportional to the concentration of the first compound, both unbound and bound to the second compound using a measurement component; and determining the equilibrium dissociation constant based on the measured signal versus time dependence.

A first solution is supplied from a first pump. A second solution is supplied from a second pump. A flow path from the first pump and the second pump to a column is switched between a first flow path and a second flow path. In the first flow path, a first mixer is located upstream of an injection part for a sample, and the second mixer is located downstream of the injection part. In the second flow path, the first mixer and the second mixer are located upstream of the injection part. The first flow path is formed in a first mode in which the sample is diluted before introduction into the column. The second flow path is formed in a second mode in which the sample is not diluted before introduction into the column.

The disclosure includes a gas analysis system comprising a control system. In some embodiments, the control system comprises a computer monitoring host, an underground coal mine gas circuit control box including an intrinsically safe PLC, a sampling pump electrically coupled to the remote power control, an explosion proof safety power box electrically coupled to the intrinsically safe optical fiber switch, and an intrinsically safe gas chromatograph electrically coupled to the intrinsically safe optical fiber switch and the flameproof and intrinsically safe power box. In some embodiments, the gas analysis system comprises a gas pipeline system having an instrument sequence tube coupled to the carrier gas output pressure sensor, the carrier gas proportional solenoid valve, the carrier gas path pressure sensor, a manual carrier gas pressure reducing valve, and a carrier gas storage.

The present disclosure relates to a method for detecting the contents of whey protein and casein, and/or the ratio thereof in milk powder by liquid chromatography-mass spectrometry. According to the method of the present disclosure, the characteristic peptide segments of whey protein and casein are selected and used for correction, and thus the accuracy and stability of detection of peptide segments by mass spectrometry using external standards are improved; in addition, the method of the present disclosure has the following advantages: easy to pretreat samples, low cost, a wide range of applicability, enable to perform quantitative detection of whey protein at one time, not affected by protein denaturation in the production process, no need to synthesize isotope internal standard, and avoiding influence of ionization efficiency and matrix in mass spectrometry detection by means of their own multiple characteristic peptide segment ratios.

A system and method for determining an efficiency of gas extraction. A chamber allows inflow and outflow of the drilling fluid. An amount of gas extracted from a drilling fluid flowing through the chamber at a constant rate during a dynamic process is measured. A dissolution curve is obtained indicative of a gas remaining in the chamber after the dynamic process. An amount drawn from the chamber during a static process subsequent to the dynamic process is measured. An amount of gas from the drilling fluid during the static process is determined from a difference between the amount of gas drawn from the chamber during the static process and an amount of gas indicated by the dissolution curve. The gas extraction efficiency is determined from a ratio of the amount of gas extracted during the static process and the amount of gas extracted during the dynamic process.

A gas chromatograph is provided which is capable of effectively reducing the amount consumed of a carrier gas, reducing the time and effort required for an operator to manually set parameters, and preventing damages to a column and a detector due to a setting mistake. In a case where a stop operation for the power supply of the gas chromatograph is performed (Yes in step S101), the flow rate of a carrier gas to be supplied to a sample vaporization chamber is decreased and the temperatures of the column and the detector are sufficiently lowered (steps S102 to S104), and then the power supply of the gas chromatograph is switched over from an ON state to an OFF state (step S106).

The present disclosure describes a differential refractometer for gradient chromatography. In an exemplary embodiment, the differential refractometer includes a solvent delay volume, an eluent flow meter coupled to an eluent inlet of a sample cell, a solvent flow regulator coupled to an outlet of the solvent delay volume and coupled to a solvent inlet of a reference cell, an instrument controller configured to receive the eluent flow rate from the eluent flow meter, configured to receive the solvent flow rate from the solvent flow regulator, configured to receive a flow rate ratio from a flow rate ratio data source, wherein the flow rate ratio indicates a ratio of the eluent flow rate to the solvent flow rate, and an optical bench configured to measure a difference between a refractive index of the eluent present in the sample cell and a refractive index of the solvent present in the reference cell.

An LC system includes a liquid delivery checker configured to execute a liquid delivery check mode of setting a predetermined flow rate to a liquid delivery pump and operating the liquid delivery pump at a timing different from analysis of a sample in order to check a liquid delivery flow rate of the liquid delivery pump, and a measuring instrument for measuring an amount of a mobile phase delivered by the liquid delivery pump during the liquid delivery check mode. The liquid delivery checker is configured to obtain an actual measurement value of a flow rate of a mobile phase when operating the liquid delivery pump by setting the predetermined flow rate to the liquid delivery pump using a measurement value obtained by the measuring instrument in the liquid delivery check mode.

A sample management device which comprises a source flow path in which a fluidic sample can flow, a volume flow adjustment unit configured to adjust a volume flow of the fluidic sample to be branched off from the source flow path at a fluidic coupling point, and a fluidic valve fluidically coupled with the source flow path and with the volume flow adjustment unit, wherein the fluidic valve is switchable into a branch off state in which the fluidic coupling point is established within the source flow path to branch off an adjustable volume of the fluidic sample from the source flow path via the fluidic coupling point while a flow of the fluidic sample in the source flow path continues.

A device for a gas chromatograph (GC) system includes an injector connected to an inlet gas line and a conduit assembly. The inlet gas line is configured to pressurize an input end of a column and to deliver a split or purge flow. The conduit assembly includes a conduit surrounding the input end of the analytical column and coupled to a carrier gas line and a controller. The inlet gas line and the carrier gas line connect to a common gas source. The controller, connected to the conduit, has a first mode delivering a flow of carrier gas which is less than the column flow during an injection period to effect a sample transfer to the column and a second mode delivering a flow of carrier gas greater than the column flow following an injection period to prevent the split or purge flow from entering the column.