Abstract: Permeable polymeric monolithic materials are prepared in a column casing. In one embodiment, the permeable polymeric monolithic materials are polymerized while pressure is applied through a piston having a smooth piston head in contact with the polymerization mixture. The pressure eliminates wall effect and changes the structure in the column. Similarly, some columns that have a tendency to swell in the presence of aqueous solutions and pressurized while the solution is applied to prevent swelling and wall effect. This procedure also changes the structure in the column. The size of the separation effective openings can be controlled by the amount of the pressure and pores eliminated. Uniformity in the direction flow is improved by controlling polymerization with radiation rather than with conducted heat.

Abstract: Permeable polymeric monolithic materials are prepared in a column casing. In one embodiment, the permeable polymeric monolithic materials are polymerized while pressure is applied through a piston having a smooth piston head in contact with the polymerization mixture. The pressure eliminates wall effect and changes the structure in the column. Similarly, some columns that have a tendency to swell in the presence of aqueous solutions and pressurized while the solution is applied to prevent swelling and wall effect. This procedure also changes the structure in the column. The size of the separation effective openings can be controlled by the amount of the pressure and pores eliminated. Uniformity in the direction flow is improved by controlling polymerization with radiation rather than with conducted heat.

Abstract: To form a smooth gradient and a preparatory liquid chromatographic system having a plurality of syringe type pumps, solvents are alternately drawn and inserted into each cylinder. The solvents are alternately drawn into and through a long narrow path formed of tubing to create axial mixing and spreading out of the interface and then are drawn into the cylinders during the refill stroke of the piston at a sufficiently high velocity to create turbulence. The drawing of the solvents into one side of the cylinder a radial distance from the center creates circular eddy currents.

Abstract: Permeable polymeric monolithic materials are prepared in a column casing. In one embodiment, the permeable polymeric monolithic materials are polymerized while pressure is applied through a piston having a smooth piston head in contact with the polymerization mixture. The pressure eliminates wall effect and changes the structure in the column. Similarly, some columns that have a tendency to swell in the presence of aqueous solutions and pressurized while the solution is applied to prevent swelling and wall effect. This procedure also changes the structure in the column. The size of the separation effective openings can be controlled by the amount of the pressure and pores eliminated. Uniformity in the direction flow is improved by controlling polymerization with radiation rather than with conducted heat.

Abstract: A chromatographic monitor includes an array of flow cells with individual light sensors that are collectively an array of photodiodes. The output from the photodiodes are multiplexed. To prevent losing information, the photodiodes are each connected to a different one of a plurality of inputs to the multiplexer through a corresponding one of a plurality of circuits that stores energy during the time the one inlet is not connected through the multiplexer to the signal processing circuitry that forms a part of an absorbance monitor. Preferably, the energy storing circuit is a non-switching circuit with low bandwidth and a flat-topped response to an impulse. This improves the signal to noise ratio. A one pole low pass filter with a (1-1/e) Dirac pulse fall time and equal to the multiplex entire cycle repeat time can perform this function and a one pole low pass filter provides satisfactory results.

Abstract: To economically perform preparatory chromatography, a plurality of pumps each having a corresponding one of a plurality of pistons and a corresponding one of a plurality of cylinders are driven by one motor to draw and pump solvent simultaneously into corresponding columns. To form a gradient, the pumps are connected to two-way valves that are connected alternately to a first solvent and a second solvent, whereby the time said valve is in a first position controls the amount of solvent drawn from the first reservoir into said pumps and the amount of time in said second position controls the amount of said second solvent drawn from the second reservoir into said pumps and the solvent is mixed in the pumping systems. The detectors are photodiodes mounted to light guides in the flow cells that generate signals related to light absorbance and communicate with a controller, whereby the controller receives signals indicating solute between the light guides and causes collection of solute.

Abstract: Permeable polymeric monolithic materials are prepared in a column casing. In one embodiment, the permeable polymeric monolithic materials are polymerized while pressure is applied through a piston having a smooth piston head in contact with the polymerization mixture. The pressure eliminates wall effect and changes the structure in the column. Similarly, some columns that have a tendency to swell in the presence of aqueous solutions and pressurized while the solution is applied to prevent swelling and wall effect. This procedure also changes the structure in the column. The size of the separation effective openings can be controlled by the amount of the pressure and pores eliminated. Uniformity in the direction flow is improved by controlling polymerization with radiation rather than with conducted heat.

Abstract: Pumping requirements for chromatograph applications are for constant flow at high and variable pressures and for accurate programmable control of liquid composition. A two-cylinder pump, pumping system, and associated controls provide an accurate, fixed flow rate. A low pressure gradient former controls composition. During the initial portion of the pumping stroke of a first piston in which fluid is being compressed due to its finite bulk modulus of elasticity its check valve remains closed, a second piston provides all the flow required at a fixed rotational speed. Then, once the first piston has reached its bottom dead center, the control system switches to a constant-pressure control mode, thereby maintaining the flow rate at a fixed value. Constant-pressure control is again switched off either when the second piston's discharge check valve closes, or when the second piston's inlet check valve opens, and pump control returns to fixed rotational speed.

Abstract: Pumping for chromatograph applications calls for constant flow at high pressures and for accurate control of liquid composition. A two-cylinder pump, and associated controls provide an accurate, fixed flow rate. During the initial portion of the pumping stroke of a first piston, while its check valve remains closed, a second piston provides all the flow required at a fixed rotational speed. Once the pressure inside the first piston's cylinder has reached that of the discharge and its discharge check valve opens, the control system switches to a constant-pressure control mode, to maintain a fixed flow rate. Constant-pressure control is switched off when the second piston's discharge check valve closes, and pump control returns to fixed rotational speed. Determining the angular displacement at which to effect these control-mode switches is carried out by monitoring changes in the discharge pressure.

Abstract: To economically perform preparatory chromatography, a plurality of pumps each having a corresponding one of a plurality of pistons and a corresponding one of a plurality of cylinders are driven by one motor to draw and pump solvent simultaneously into corresponding columns. To form a gradient, the pumps are connected to two-way valves that are connected alternately to a first solvent and a second solvent, whereby the time said valve is in a first position controls the amount of solvent drawn from the first reservoir into said pumps and the amount of time in said second position controls the amount of said second solvent drawn from the second reservoir into said pumps and the solvent is mixed in the pumping systems. The detectors are photodiodes mounted to light guides in the flow cells that generate signals related to light absorbance and communicate with a controller, whereby the controller receives signals indicating solute between the light guides and causes collection of solute.

Abstract: Signals obtained in High Performance Liquid Chromatography (HPLC) are notoriously noisy. The signal can be improved by increasing the path length of the light passing through the sample, but increased path length also invites greater refraction and reflection of that light. A novel approach is to utilize a number of photocell sensors lined up along a capillary through which the solution passes. Through careful measurement and calculation, a signal for a single fluid particle can be produced by all the photocell sensors. By incorporating an appropriate delay between each signal, to take into account the finite speed of the fluid, the resulting plurality of noisy signals can be summed or statistically correlated. The signal, containing the important information about the fluid, will increase with the number of photocells used, while the noise increases by the square root of the number of photocells used. The signal to noise ratio, then, increases as the square of the number of photocells used.

Abstract: Signals obtained in capillary High Performance Liquid Chromatography (HPLC) are notoriously noisy. The signal can be improved by increasing the path length of the light passing through the sample stream, but increased path length decreases resolution (resolving N closely spaced peaks in the actual separation into N peaks of almost equal separation on the chromatogram. A novel approach is to operate on segments of the chromatogram signal, averaging, integrating, or correlating the data within the segment. This approach may be utilized with analog or digital signals. The important information, contained in the integrated, summed or correlated signal, will increase the chromatographic signal relative to the noise information.

Abstract: Signals obtained in capillary High Performance Liquid Chromatography (HPLC) are notoriously noisy. The signal can be improved by increasing the path length of the light passing through the sample stream, but increased path length decreases resolution (resolving N closely spaced peaks in the actual separation into N peaks of almost equal separation on the chromatogram. A novel approach is to utilize a number of photocell sensors lined up along a capillary through which the solution passes. In one embodiment of this invention, the flow of the solution is stopped with the solvent spike oriented with a particular photocell sensor. Then a single, continuous scan or multiple scans of a section of the quiescent solution may be taken and integrated, summed, or statistically correlated. In another embodiment, a solvent spike is detected and tracked. A set of photocell sensors is chosen at increments of time such that the leading photocell is at the solvent spike. The set of photocells is scanned repeatedly.

Abstract: Signals obtained in capillary High Performance Liquid Chromatography (HPLC) are notoriously noisy. The signal can be improved by increasing the path length of the light passing through the sample stream, but increased path length decreases resolution (resolving N closely spaced peaks in the actual separation into N peaks of almost equal separation on the chromatogram. A novel approach is to utilize a number of photocell sensors lined up along a capillary through which the solution passes. In one embodiment of this invention, the flow of the solution is stopped with the solvent spike oriented with a particular photocell sensor. Then a single, continuous scan or multiple scans of a section of the quiescent solution may be taken and integrated, summed, or statistically correlated. In another embodiment, a solvent spike is detected and tracked. A set of photocell sensors is chosen at increments of time such that the leading photocell is at the solvent spike. The set of photocells is scanned repeatedly.

Abstract: To economically perform preparatory chromatography, a plurality of pumps each having a corresponding one of a plurality of pistons and a corresponding one of a plurality of cylinders are driven by one motor to draw and pump solvent simultaneously into corresponding columns. To form a gradient, the pumps are connected to two-way valves that are connected alternately to a first solvent and a second solvent, whereby the time said valve is in a first position controls the amount of solvent drawn from the first reservoir into said pumps and the amount of time in said second position controls the amount of said second solvent drawn from the second reservoir into said pumps and the solvent is mixed in the pumping systems. The detectors are photodiodes mounted to light guides in the flow cells that generate signals related to light absorbance and communicate with a controller, whereby the controller receives signals indicating solute between the light guides and causes collection of solute.

Abstract: Pumping requirements for chromatograph applications are for constant flow at high and variable pressures and for accurate programmable control of liquid composition. A two-cylinder pump, pumping system, and associated controls provide an accurate, fixed flow rate. A low pressure gradient former controls composition. During the initial portion of the pumping stroke of a first piston in which fluid is being compressed due to its finite bulk modulus of elasticity its check valve remains closed, a second piston provides all the flow required at a fixed rotational speed. Then, once the first piston has reached its bottom dead center, the control system switches to a constant-pressure control mode, thereby maintaining the flow rate at a fixed value. Constant-pressure control is again switched off either when the second piston's discharge check valve closes, or when the second piston's inlet check valve opens, and pump control returns to fixed rotational speed.

Abstract: Pumping requirements for chromatograph applications are for constant flow at high and variable pressures and for accurate programmable control of liquid composition. A two-cylinder pump, pumping system, and associated controls provide an accurate, fixed flow rate. A low pressure gradient former controls composition. During the initial portion of the pumping stroke of a first piston in which fluid is being compressed due to its finite bulk modulus of elasticity its check valve remains closed, a second piston provides all the flow required at a fixed rotational speed. Then, once the pressure inside the first piston's cylinder has reached that of the discharge and its discharge check valve opens, the control system switches to a constant-pressure control mode, thereby maintaining the flow rate at a fixed value. Constant-pressure control is again switched off when the second piston's discharge check valve closes, and pump control returns to fixed rotational speed.

Abstract: Permeable polymeric monolithic materials are prepared in a column casing. In one embodiment, the permeable polymeric monolithic materials are polymerized while pressure is applied through a piston having a smooth piston head in contact with the polymerization mixture. The pressure eliminates wall effect and changes the structure in the column. Similarly, some columns that have a tendency to swell in the presence of aqueous solutions and pressurized while the solution is applied to prevent swelling and wall effect. This procedure also changes the structure in the column. The size of the separation effective openings can be controlled by the amount of the pressure and pores eliminated.

Abstract: Permeable polymeric monolithic materials are prepared in a column casing. In one embodiment, the permeable polymeric monolithic materials are polymerized while pressure is applied through a piston having a smooth piston head in contact with the polymerization mixture. The pressure eliminates wall effect and changes the structure in the column. Similarly, some columns that have a tendency to swell in the presence of aqueous solutions and pressurized while the solution is applied to prevent swelling and wall effect. This procedure also changes the structure in the column. The size of the separation effective openings can be controlled by the amount of the pressure and pores eliminated. Uniformity in the direction flow is improved by controlling polymerization with radiation rather than with conducted heat.

Abstract: Permeable polymeric monolithic materials are prepared in a column casing. In one embodiment, the permeable polymeric monolithic materials are polymerized while pressure is applied through a piston having a smooth piston head in contact with the polymerization mixture. The pressure eliminates wall effect and changes the structure in the column. Similarly, some columns that have a tendency to swell in the presence of aqueous solutions and pressurized while the solution is applied to prevent swelling and wall effect. This procedure also changes the structure in the column. The size of the separation effective openings can be controlled by the amount of the pressure and pores eliminated.