An ion exchange chromatographic packing material is described that includes a copolymer grafted to support resin particles. The copolymer includes an ion exchange group, an ionic crosslinking group configured to ionically bind to the ion exchange group, and an adjustable ionization state group having at least a first net charge at the first pH and a second net charge at the second pH. An overall first net charge of the chromatographic packing material at the first pH is opposite in polarity to the overall second net charge of the chromatographic packing material. This allows impurities to be removed from the chromatographic packing material at the second pH.

An ion exchange chromatographic packing material is described that includes a copolymer grafted to support resin particles. The copolymer includes an ion exchange group, an ionic crosslinking group configured to ionically bind to the ion exchange group, and an adjustable ionization state group having at least a first net charge at the first pH and a second net charge at the second pH. An overall first net charge of the chromatographic packing material at the first pH is opposite in polarity to the overall second net charge of the chromatographic packing material. This allows impurities to be removed from the chromatographic packing material at the second pH.

Systems and methods are disclosed for controlling performance of a mixed ion exchange media comprising two or more media. The weighted average of a quantity of the first media having a first rate of exchange to a quantity of a second media having a second rate of exchange is determined based on predetermined requirements for the resulting mixed media. After determining the weighted average, the first and second media are mixed resulting in a mixed media having a third rate of exchange. The mixed media is introduced to an ion exchange column. Contaminated liquid is then introduced to the column creating a mass transfer zone within the column. The mixed media is generally considered optimized when it meets three conditions simultaneously: 100% safety limitation, 100% media capacity used, and effluent criteria are met.

An analytical system comprises a chromatography column configured to separate a sample into one or more analytes; an ion removal device configured to remove at least ions of one charge from the mobile phase, the ion removal device fluidly coupled to an output of the chromatography column; an ion selective sensor configured to measure a signal corresponding to an activity of the ions of one charge in the mobile phase, the ion selective sensor fluidly coupled to an output of the ion removal device; an optional diverter valve that can interrupt the flow of the mobile phase; and a microprocessor configured to monitor the signal of the ion selective sensor and to either switch the optional diverter valve to interrupt the flow of the mobile phase or turn off the pump when the signal is greater than a predetermined threshold.

A system for self-regulating a suppressor includes an ion chromatography suppressor, a power supply for applying an electric potential to the suppressor, and a control unit configured to provide an offset voltage Vos and an applied voltage V.sub.A to the suppressor, measure a current of the suppressor responsive to the offset and applied voltages V.sub.OS and V.sub.A, determine a suppressor state of the suppressor based upon the measured current, and adjust the offset voltage Vos based upon the suppressor state. A method for self-regulating a suppressor is also disclosed.

The invention provides methods for quantifying a non-ionic surfactant in a composition comprising a polypeptide and the non-ionic surfactant, where the quantification exhibits reduced interference between the non-ionic surfactant and the polypeptide. Also provided are methods where the composition further includes N-acetyl tryptophan, and the quantification exhibits reduced interference between the non-ionic surfactant, the polypeptide, and N-acetyl tryptophan.

The invention provides methods for quantifying a non-ionic surfactant in a composition comprising a polypeptide and the non-ionic surfactant, where the quantification exhibits reduced interference between the non-ionic surfactant and the polypeptide. Also provided are methods where the composition further includes N-acetyl tryptophan, and the quantification exhibits reduced interference between the non-ionic surfactant, the polypeptide, and N-acetyl tryptophan.

An apparatus for suppressing an eluent of an aqueous sample stream including analyte ions of one charge, positive or negative, comprises a primary channel member, a first block, a first regenerant flow channel, a first charged barrier, a second block, a second regenerant flow channel, a second charged barrier, a first stationary flow-through ion exchange material, and optionally a first electrode and a second electrode. The first stationary flow-through ion exchange material comprises a polyolefin substrate having a functional polymer layer disposed thereon. The polyolefin substrate has a pore structure with a pore size ranging from about 5 microns to about 250 microns. The functional polymer layer has a thickness ranging from about 1 micron to about 20 microns, and a layer pore structure having a pore size ranging from about 1 nm to about 100 nm. The functional polymer layer comprises an ion exchange layer.

An apparatus for suppressing an eluent of an aqueous sample stream including analyte ions of one charge, positive or negative, comprises a primary channel member, a first block, a first regenerant flow channel, a first charged barrier, a second block, a second regenerant flow channel, a second charged barrier, a first stationary flow-through ion exchange material, and optionally a first electrode and a second electrode. The first stationary flow-through ion exchange material comprises a polyolefin substrate having a functional polymer layer disposed thereon. The polyolefin substrate has a pore structure with a pore size ranging from about 5 microns to about 250 microns. The functional polymer layer has a thickness ranging from about 1 micron to about 20 microns, and a layer pore structure having a pore size ranging from about 1 nm to about 100 nm. The functional polymer layer comprises an ion exchange layer.

Ion exchange stationary phases are prepared with diprimary diamines for applications such as separating samples that contain polyvalent anions. The ion exchange stationary phase includes a series of condensation polymer reaction products bound to a substrate. The condensation polymer products are formed with diprimary diamines and polyepoxide compounds. The ion exchange stationary phases described herein are capable of separating monovalent and highly polyvalent anions relatively quickly with relatively low eluent concentrations in one chromatographic run.