Dionex Corporation

Xertex Corporation

Maria A Rey

John M Riviello

Christopher A Pohl

Jacek J Jagodzinski

Andrei Bordunov

Yoshihiro Takahashi

A method for making a weak cation-exchange (carboxylic acid) medium comprising contacting a solution of a functional organic polymer having carbon to carbon double bond unsaturation and having weak cationic exchange functional moieties or precursors thereof in a solvent with a substrate having an organic polymer surface, evaporating said solvent and breaking said double bond under conditions to cause the functional organic polymer to covalently bond to the substrate surface and to cross-link to form a cross-linked functional polymer layer covalently bound to the substrate surface. The medium produced by the method.

Polymer substrate coated with weak cationic-exchange functional layer

In accordance with the present invention, an improved bifunctional cation-exchange composition has been formed which comprises synthetic resin support particles and both crown ether and non-crown ether functional groups attached thereto. The compositions of the present invention provide for novel, enhanced cation separation capabilities and, depending upon the type of functional groups employed, permit effective separation of cations which elute at approximately the same time off standard and commonly used cation-exchange columns. The presently described bifunctional cation-exchange compositions also permit the effective separation of one cation from a mixture comprising another cation that is present at a significantly greater concentration. Formed articles and methods employing the bifunctional cation-exchange composition are also provided.

Bifunctional crown ether-based cation-exchange stationary phase for

An ion chromatographic apparatus and method for on-column preconcentration of trace ionic contaminants for quantitative trace analysis by ion chromatography. The method includes the multi-cycle, sequential steps of loading and purging of sample solution into and out of a sample injection loop to cumulatively preconcentrate a separator column with a cumulative amount of sample. Each purging step includes directing pressurized liquid, at a substantially constant rate and for a predetermined period of time to the sample injection loop, to drive up to about 98% of the known volume of the sample solution from the sample injection loop. In turn, this flushed volume of sample solution passes through an ion exchange resin column for concentration of the trace ionic contaminants in the resin.

Multicycle loop injection for trace analysis by ion chomatography

Multicycle loop injection for trace analysis by ion chromatography

X-ray fluorescence spectrometer for determining the sulfur content of oil and other matrices, and method of calibrating the same. The spectrometer comprises a pulse height analyzer and a computer for analyzing the energy spectrum of photons emitted by a sample in regions corresponding to the energy levels of photons emitted by sulfur and the target line x-rays scattered by the sample. The windows through which the energy is sampled are adjusted to provide a calibration curve of predetermined shape, and a built-in standard is analyzed and a value corresponding to the ratio of the relative intensities of the fluorescent energy from the standard and the scattered target line x-ray radiation is stored during initial calibration of the system. Thereafter, the system is recalibrated simply by analyzing the build-in standard again, adjusting the sampling windows, and adjusting a constant in the relationship by which the sulfur content is determined to compensate for drift in the system.

Growing community of inventors

San Jose, CA, United States of America

Maria A Rey