The present disclosure relates to methods, compositions and kits useful for the enhanced pH gradient cation exchange chromatography of a variety of analytes. In various aspects, the present disclosure pertains to chromatographic elution buffer solutions that comprise a first buffer salt, a second buffer salt, a third buffer salt, and fourth buffer salt. The first buffer salt may be, for example, a diprotic acid buffer salt, the second buffer salt may be, for example, a divalent buffer salt with two amine groups, the third buffer salt may be, for example, a monovalent buffer salt comprising a single amine group, and the fourth buffer salt may be, for example, a zwitterionic buffer salt. Moreover, the buffer solution has a pH ranging from 3 to 11.

An online measuring system for the semi-volatile organic compounds in the gas phase is provided in the disclosure. The system comprises a filter head, a three-way electromagnetic valve, an enrichment-thermal desorption device, a two-position six-way valve, a mass flow controller, a gas pump, a gas chromatograph, a primary capture trap, a secondary focus trap, and a gas supply and pressure control system, the inlet of the filter head is connected to be provided with a sampling object, the outlet of the filter head is connected with the port B of the three-way electromagnetic valve through a passivated stainless steel tube, the port C of the three-way electromagnetic valve is connected with the inlet of the primary capture trap through a passivated stainless steel tube, and the port A of the three-way electromagnetic valve is connected to the gas supply and pressure control system through a passivated stainless steel tube.

An online measuring system for the semi-volatile organic compounds in the gas phase is provided in the disclosure. The system comprises a filter head, a three-way electromagnetic valve, an enrichment-thermal desorption device, a two-position six-way valve, a mass flow controller, a gas pump, a gas chromatograph, a primary capture trap, a secondary focus trap, and a gas supply and pressure control system, the inlet of the filter head is connected to be provided with a sampling object, the outlet of the filter head is connected with the port B of the three-way electromagnetic valve through a passivated stainless steel tube, the port C of the three-way electromagnetic valve is connected with the inlet of the primary capture trap through a passivated stainless steel tube, and the port A of the three-way electromagnetic valve is connected to the gas supply and pressure control system through a passivated stainless steel tube.

A method of making Lu-177 involving dissolving enriched Yb.sub.2O.sub.3, loading dissolved enriched Yb.sub.2O.sub.3 on a first guard column containing resin prepared from (2-ethyl-1-hexyl)phosphonic acid mono(2-ethyl-1-hexyl)ester (HEH[EHP]), passing a first separation of a stream exiting from first guard column through a first resin cartridge containing dipentyl pentylphosphonate, collecting Lu-177 onto a first collection column having resin containing tetraoctyl diglycolamide (DGA), loading an exiting stream from first collection column on a second guard column containing resin prepared from (2-ethyl-1-hexyl)phosphonic acid mono(2-ethyl-1-hexyl)ester (HEH[EHP]); passing a first separation of a stream exiting from second guard column through a second resin cartridge containing dipentyl pentylphosphonate; collecting Lu-177 onto a second collection column having resin containing DGA; passing a second separation of a stream exiting from second guard column through a third resin cartridge containing dipentyl pentylphosphonate; and collecting Lu-177 having passed through the third resin cartridge onto a third collection column having resin containing DGA.

This invention relates to a micro-device for detecting volatile compounds comprising: an input (E) and an output (S); collection means (2) for taking a gas sample containing at least one compound to be detected; sampling means enabling a gas volume of 100 mL or less to be sampled, arranged after the collection means; injection means (3) of said gas sample; separation means (5) of the compound to be detected in the gas sample; compound detection means (6); and a gas circulation circuit (1) located downstream of the collection means and passing through the sampling means, injection means (3), separation means (5) and detection means (6);

characterized in that the gas circulation circuit (1) has a volume of between 0.2 cm.sup.3 and 2.0 cm.sup.3.

A liquid chromatograph includes: a concentration column for capturing a target component; an analysis column for separating the target component from other components; first passage-switching units for switching between the state of forming a passage through which a sample-introduction mobile phase containing the liquid sample is fed to the concentration column, and the state of forming a passage through which an eluant for eluting the target component captured in the concentration column is fed to the concentration column; a storage unit for storing the eluant; and a second passage-switching unit for switching between the state of forming a passage through which an analysis mobile phase is fed to the analysis column and a passage through which the eluant from the concentration column is fed to the storage unit, and the state of forming a passage through which analysis mobile phase is fed to the analysis column via the storage unit.

An apparatus for chemical separations includes a first substantially rigid microfluidic substrate defining a first fluidic port; a second substantially rigid microfluidic substrate defining a second fluidic port; and a coupler disposed between the first and second substrates, the coupler defining a fluidic path in fluidic alignment with the ports of the first and second substrates. The coupler includes a material that is deformable relative to a material of the first substrate and a material of the second substrate. The substrates are clamped together to compress the coupler between the substrates and form a fluid-tight seal.

A method and apparatus for enabling larger injection volumes and for reducing extra column effects in chromatographic separations using focusing pre-columns placed upstream of the analytical, or preparative, column with applications in any chromatographic system where the requirement is that the focusing pre-column, placed upstream of the analytical column, allows larger injection volumes to be utilized and, by enabling efficient focusing of solutes onto the analytical column, results in a significant reduction of band broadening due to extra-column effects which act upstream of the analytical column.

Systems and methods for concentrating an analyte preparatory to analysis thereof include processing the effluent of an analyte concentrator to produce an eluent for eluting an analyte retained in the same or separate concentrator, and systems implementing the same. The analyte concentrator system connects the effluent outlet of an analyte concentrator column to an eluent generation module such that the substantially analyte-free effluent discharged from the analyte concentrator column passes fluidly into the eluent generation module. Eluent generated from the substantially analyte-free effluent in the eluent generation module is likewise substantially free of the analyte. The systems and methods can minimize and/or (substantially) eliminate background signal during analysis of the concentrated analyte.

A double-sided diaphragm micro gas-preconcentrator has a micro-gas chamber which is formed by stacking an upper silicon substrate with a lower silicon substrate with a back-on-face configuration. One or more suspended membranes are provided on every silicon substrate. The silicon where the suspended membrane is provided is completely removed for forming a cavity. A thin-film heater is deposited on every suspended membrane. A sorptive film is coated on an inner wall of every suspended membrane. Thus, the upper and lower sides of the preconcentrator in the present invention are suspended membranes, which improve the area of the sorptive film on the diaphragm. As a result, the preconcentrating factor is improved while keeping the small heat capacity, fast heating rate, and low power consumption features of the planar diaphragm preconcentrator.