The present invention addresses the problem of providing a novel method for the pretreatment of a biological sample containing lenalidomide enantiomer and thereby establishing a simple and accurate method for the quantitative analysis of lenalidomide enantiomer. In the present invention, the racemization and decomposition of lenalidomide enantiomer in a biological sample can be prevented by the deproteinization under acidic conditions of the biological sample containing lenalidomide enantiomer, and the lenalidomide enantiomer can be simply and accurately quantitatively analyzed by subjecting to HPLC the biological sample that has been pretreated in such a way.

A manifold assembly has a manifold and can be located between a block and a plate, and serve as a stator for a valve or other component. The manifold, block or plate can have a plurality of ports either integral thereto or removably connected thereto, with the ports adapted to receive and sealingly engage with a tube having an inner tube layer, an outer tube layer, a sleeve, a tip portion, and a nut. Each of the nut, sleeve, inner and outer tubing layers, and tip portion have a passageway therethrough, with at least the passageways in the sleeve, tip portion, outer tube layer, and nut adapted to allow the inner tube layer to pass therethrough or extend over the inner layer. The ends of the tip portion and inner layer together can define a substantially flat surface which can form a seal in a flat-bottomed port of the manifold, block, or plate, which can be used in a component in an analytical instrument system, including for example a liquid chromatography system. The nut, tube, ferrule, and transfer tube or liner tube may comprise biocompatible materials. In addition, the nut may have a slot, such as a slot adapted to allow the tube and the nut to be easily and quickly separated or to allow a portion of the tube to be easily and quickly inserted in the nut.

Exemplary embodiments of the present disclosure are directed to limiting a rate or pressurization in a reconfigurable pressurized flow system for which different system configurations can have different system volumes. In exemplary embodiments, the system can determine a limit for the rate of pressurization by configuring the system for a closed system rate of pressurization, measuring the closed system rate of pressurization at a set flow rate, and determining a relationship between the closed system rate of pressurization and the flow rate. The system can use the relationship to dynamically set the limit for different flow rates in the system.

The present disclosure relates to controlling the average enthalpy of a mobile phase in a column that is part of a carbon dioxide based chromatographic system. By controlling average enthalpy, separations can be optimized, and method development and transfer between different carbon dioxide based separation systems can be more efficient.

A system and method for performing staggered separations are described. The system includes a plurality of solvent pumps; a plurality of proportioning valves each being in fluid communication with one of the solvent pumps, each proportioning valve having an inlet to receive a solvent from the respective one of the solvent pumps and having a plurality of outlets, wherein the proportioning valves are configured to control a flow of the solvent from each of the outlets; and a plurality of separation devices each in fluid communication with one of the outlets. Each of the separation devices receives a solvent mixture having a composition defined by the flows of the solvents from each of the respective outlets.

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 liquid chromatographic system includes a column, a needle, a valve, a pump, and an analysis flow path. The valve sets the analysis flow path by switching between a first flow path through which an eluent flows from the valve to the column via the needle and a second flow path through which the eluent flows from the valve to the column not via the needle. The first flow path can be cleaned by drive of a first cleaning pump while the first flow path is set, and the second flow path can be cleaned by drive of the first cleaning pump while the second flow path is set.

A method of identifying a sulfur-treated food product, the method including: providing a sample including a food product; analyzing the sample using an analytical method to determine whether the sample includes tryptophan sulfonate; and identifying based on whether the sample includes tryptophan sulfonate that the food product is sulfur-treated, wherein the presence of tryptophan sulfonate indicates that the food product is sulfur-treated.

A liquid chromatographic system includes a first cleaning pump that supplies a cleaning solution to a first valve, a selector valve connected to a first column and a second column, the selector valve switching an object to be connected to a detector that analyzes a separated sample between the first column and the second column, and a controller. The controller can have the first cleaning pump driven to clean the selector valve with the cleaning solution that flows through a first analysis flow path.

A method for operating a chromatography system comprises the system assuming a first configuration, wherein a first pump is fluidly connected to a first separation column, and a second pump is fluidly connected to a second separation column. Further the method comprises while in the first configuration the first pump providing a fluid to the first separation column, the second pump providing a fluid to the second separation column, determining a second pump target pressure, determining a first pump target pressure based on the second pump target pressure, and setting the first pump to provide fluid at the first pump target pressure. Furthermore, the method comprises the system switching to a second configuration, wherein the first pump is fluidly connected to the second separation column, while the first pump provides fluid at the first pump target pressure. Additionally disclosed are a respective chromatography system and computer program product.