There is provided a system for separation of analytes in a solution. The system encompasses a disposable cartridge enclosing a sorbent for binding the analytes in a solution and a conduit establishing a fluid link to a valve having a holding-loop to achieve elution through the cartridge at low pressures. The valve is switchable to a position following the elution from the cartridge for emptying through an outlet port at high pressures such as those required for moving liquid through chromatographic columns.

The present disclosure relates to methodologies, systems and apparatus for controlling pressure in a CO.sub.2-based chromatography system. A first CO.sub.2 pump operates in constant flow mode and delivers CO.sub.2 to a chromatography column, and liquid modifier is introduced to the chromatography column according to a gradient. A second CO.sub.2 pump is disposed downstream of the column and operates in constant pressure mode to introduce CO.sub.2 into a flow stream at an output of the column. Liquid modifier is also introduced into the flow stream at the output of the column according to a reverse gradient compared to the gradient entering the chromatography column.

The present disclosure relates to methodologies, systems and apparatus for controlling pressure in a CO.sub.2-based chromatography system. A first pressure control element is located downstream of a CO.sub.2-based chromatography system and is disposed to control pressure within the column. A split restrictor is located downstream of the primary pressure control element and is disposed to divert a portion of the mobile phase flow to a detector. A second pressure control element is located downstream of the split restrictor and is disposed to control pressure at the restrictor. While the first pressure control element executes a pressure-controlled gradient separation, the second pressure control element maintains a constant pressure at the restrictor. During a composition-programmed gradient separation, the second control element maintains a constant pressure at the split restrictor while the first pressure control element maintains a constant average density across the column.

Method for controlling a liquid chromatography system comprising a system pump and a column in fluid communication with the system pump by a fluid flow path, the method comprising the steps: registering the system pressure at a flow path position close to the system pump, controlling the operation of the system pump in response to the registered system pressure, estimating a pre-column pressure based on the registered system pressure, the characteristics of the flow path, and the viscosity and flow-rate of the liquid in the system, and controlling the operation of the system pump in response to the estimated pre-column pressure.

A device comprising a pressure monitor and a control means that receives a signal representing measured pressure at the pressure monitor and controls the controllable elements of a fluid system is utilized to monitor a fluid system for error conditions, to optimize operations and to diagnose the fluid system. By following a testing protocol that selectively enables parts of the system, the control means narrows the list of possible falling components. Comparing the measured pressure against normal pressures allows the device to identify error conditions. Determining the volume of fluid being transported and controlling the duration of the flow optimizes operation of the fluid system.

Provided are methods for determining the apolipoprotein E (ApoE) phenotype in a sample by mass spectrometry; wherein the ApoE allele(s) present in the sample is determined from the identity of the ions detected by mass spectrometry. In another aspect, provided herein are methods for diagnosis or prognosis of Alzheimer's disease or dementia.

A method of controlling the impurities in a cyclosporin A eye gel. A high performance liquid chromatography is performed, and chromatographic conditions are as follows: the detection wavelength is 210-230 nm; the column temperature is 60-68? C.; the flow rate is 0.8-1 ml/min; and the mobile phase A is: THF-water-phosphoric acid. The method of controlling impurities solves the problem of excipients interference and separation of many impurities at the same time, it also provides an effective method for the formulation of quality standard of impurities in this kind of preparation.

A method of liquid chromatography includes providing one or more solvent reservoirs, providing a solvent pump, drawing one or more solvents into the pump in response to a pressure drop that promotes outgassing of the solvents, and dispersing outgassed bubbles into smaller bubbles to promote re-dissolution of the gas. A liquid-chromatography apparatus includes at least two solvent reservoirs, a pump, at least one bubble-dispersing unit that receives a pressurized flow of proportioned solvents from the pump, and a control unit. The control unit includes a processor and a memory that stores instructions; the control unit controls proportioning of solvents to obtain a preselected solvent composition, and pumping at flow rates to support preparative-scale or process-scale liquid chromatography.

Certain embodiments of the invention provides a method for monitoring level of saturation of a chromatography media in a column, which method comprises measuring a first pressure at the inlet of an unloaded column; measuring a second pressure at the inlet from a loaded column; and comparing the first and second pressure measurement of determine the level of saturation of the chromatography media. Embodiments of the invention also provide related methods for controlling a chromatography system and methods for controlling a periodic counter current chromatography system, as well as a chromatography system suitable for use with the novel methods.

A reconfigurable capillary liquid chromatography system includes a solvent delivery manager including a first solvent pump assembly including a first pump housing or mount. A base module is further provided including a base module housing which is user accessible, or a base module bracket, and an injection valve for sample injection to a liquid chromatography column. The injection valve has an inlet port for receiving a sample and the injection valve is mounted in or on the base module housing or the base module bracket. The solvent delivery manager is configured to deliver solvent to the injection valve. A reconfigurable control system is also provided for controlling the reconfigurable capillary liquid chromatography system. The system is selectively user configurable to removably add any one or more additional components to the system such that the base module including the base module housing or bracket, the first pump housing or mount, and the user selected additional components fit within a predetermined system envelope, the additional components including any one or more of the following; a second solvent pump assembly having a second pump housing or mount, such that the selected second pump assembly is removably mountable on or within the base module housing or bracket for incorporation within the solvent delivery manager; a third pump assembly for a sample delivery module, the third pump assembly having a third pump housing or mount, such that the selected third pump assembly is removably mountable on or within the base module housing or bracket; a sample delivery module which is adapted for fluidic connection to the injection valve, wherein the selected sample delivery module is removably mountable on or within the base module housing or bracket; and an optical detector module having a detector housing or mount, such that the selected optical detector housing or mount is removably mountable on or within the base module housing or bracket. The control system is reconfigurable according to the user selected additional components.