The Dow Chemical Company

Hernan J Cortes

Curtis D Pfeiffer

Robert M Campbell

Bruce E Richter

Steven J Martin

Richard G Melcher

Gary L Jewett

R Paul Himes

Charles G Smith

James C Davis

Timothy S Stevens

Steven R Erskine

Curtis D Pfeffer

Yvonne M Walbroehl

Highly efficient microcolumns suitable for use in chromatography, especially size excusion chromatography, are presented along with the method for making them. The method involves first obtaining a microcolumn having a first end and a second end, said microcolumn having an inner diameter of less than 1 mm. Then a slurry is prepared containing a packing material and a liquid solvent, said slurry having a concentration of more than 10 milliliters of solvent per gram of packing material. A retaining means is placed at the second end of the microcolumn, said retaining means being effective for retaining the packing material while allowing the liquid solvent to pass through the retaining means. The slurry is then added to the first end of the microcolumn at a constant pressure, said pressure being less than about 680 atmospheres. After a length of column suitable for use in chromatography has been filled, the addition of the slurry is stopped. The column is allowed to slowly decompress by allowing the solvent to exit the second end of the column.

Microcolumns for chromatography and method for making same

Apparatus and method for on-line coupled liquid chromatography and gas chromatography analysis. The system includes a high-volume, liquid vaporizing chamber, or interface capillary tube which allows injection of a substantial volume of sample-carrying eluent and concentrates bands, obviating adverse effects on the resolution or peak shape of the components of interest. The vaporizing chamber is interposed between a packed or wall-coated open tubular capillary liquid chromatographic column and a capillary gas chromatographic column. The capillary liquid chromatographic column permits the use of small volumes of eluent and reduced flow rates.

On-line coupled liquid and gas chromatography system with an interface

An on-line multidimensional system which includes a liquid chromatograph having an on-line connection to a pyrolysis probe, which in turn has on-line connection to a gas chromatograph. Preferred applications use a size-exclusion chromatograph coupled to a pyrolysis probe coupled to a gas chromatograph to simultaneously produce composition as a function of molecular weight/size information for polymeric materials.

Multidimensional chromatographic system

On-line supercritical fluid extraction multidimensional chromatographic

An on-line multidimensional chromatographic system and method which couples a liquid chromatograph to a supercritical fluid chromatograph. The system includes an inlet column for depositing a fraction of interest eluting from the liquid chromatograph, an interface interposed between the inlet column and the supercritical fluid chromatograph for receiving and trapping an analyte from the deposited fraction on an impactor surface, and a valve arrangement for controlling fluid flow throughout the system. After the fraction of interest has been deposited in the inlet column, the liquid chromatograph solvent is removed from the inlet column, and then the deposited fraction is extracted from the inlet column in a supercritical fluid stream. The supercritical fluid stream is directed into the interface, where the analyte is trapped while the supercritical fluid is decompressed and vented. A subsequent supercritical fluid stream is then used to introduce the trapped analyte directly into the analytical column of the supercritical fluid chromatograph. The system and method can also be used to introduce samples contained in large volumes of solvent without the prior liquid chromatographic separation.

On-line multidimensional chromatographic system with large volume

There is provided an apparatus for monitoring the relative concentration of an analyte in a fluid stream, with such apparatus including a capillary tube for containing the flowing fluid, optics for directing a single beam of monochromatic light through the capillary tube to produce a diffraction pattern having a number of interference fringes. A translatable photodiode is provided to monitor a portion of one of the fringes passing through a light limiting slit, whereby a signal proportional to the concentration of the analyte in the fluid is produced based upon the varying intensity of the monitored fringe. The capillary tube is preferably provided as a fused silica member having an inner flow diameter of 100 micrometers or less.

Capillary fluid stream concentration measuring apparatus and method

An on-line multidimensional chromatographic system and method which couples a liquid chromatograph to a supercritical fluid chromatograph. The system includes an inlet column for depositing a fraction of interest eluting from the liquid chromatograph, an interface interposed between the inlet column and the supercritical fluid chromatograph for receiving and trapping an analyte from the deposited fraction on an impactor surface, and a valve arrangement for controlling fluid flow throughout the system. After the fraction of interest has been deposited in the inlet column, the liquid chromatograph solvent is removed from the inlet column, and then the deposited fraction is extracted from the inlet column in a supercritical fluid stream. The supercritical fluid stream is directed into the interface, where the analyte is trapped while the supercritical fluid is decompressed and vented. A subsequent supercritical fluid stream is then used to introduce the trapped analyte directly into the analytical column of the supercritical fluid chromatograph.

Apparatus and method for extracting a component from a sample across a membrane into an extractant and then injecting the extracted sample component into a chromatographic eluent and onto a chromatographic column to chromatographically analyze the extracted sample component. In essence, the advance provided by this invention is that the extractant and the eluent are the same and only one pump is used for pumping the eluent and extractant. In prior apparatus and methods in this field, the extractant and the eluent were separate and each had its own pump.

Apparatus for membrane assisted liquid chromatography

Apparatus and method for on-line coupled liquid chromatography and gas chromatography analysis includes a retention gap which allows injection of a substantial volume of sample-carrying eluent and concentrates bands, obviating adverse effects on the resolution or peak shape of the components of interest. The retention gap is used to simultaneously receive and vaporize liquid solvent in a manner highly suitable for purposes of gas chromatographically separating solutes of interest dispersed in the liquid chromatography solvent.

On-line coupled liquid and gas chromatography system

Method for membrane assisted liquid chromatography

A versatile and highly sensitive procedure of indirect photometric chromatography in which a variable capacity pH dependent weakly basic or weakly acidic ion exchange medium is used in the chromatographic column to effect ion separations. Adjusting eluent pH allows increased detection limits without extended analysis time, reduced column efficiency, or the need for a battery of conventional strongly basic/acidic ion exchange columns.

Indirect-photometric chromatography done in and with a variable capacity

A method for analyzing the serum phase of a latex solution by permeating low molecular weight components present in the serum phase for a known amount of time through a size selective permeable membrane to a dialysate fluid and sequentially injecting the dialysate fluid into a liquid chromatograph for subsequent analysis.

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Midland, MI, United States of America

Hernan J Cortes