A particulate material for chromatographic use comprising silica particles is provided having a skeleton structure containing silsesquioxane cage moieties. The material is useful as a chromatographic material, for example in HPLC. The silica particles may be hybrid organo-silica particles wherein the silsesquioxane moieties comprise a cage structure having silicon atoms positioned at corners of the cage wherein one or more silicon atoms positioned at the corners of the cage carry an organic group. A preferred method of preparing the particulate material comprises hydrolysing a silsesquioxane as a co-component of a hydrolysis mixture, especially in a Stber or modified Stber process.

The present disclosure relates to the determination of analytes in a sample using chromatography. The present disclosure provides methods of separating an analyte from a sample. A mobile phase is flowed through a chromatography column. The mobile phase includes about 0.005% (v/v) to about 0.20% (v/v) difluoroacetic acid and less than about 100 ppb of any individual metal impurity. A sample including the analyte is injected into the mobile phase. The analyte is separated from the sample.

The present disclosure relates to the determination of analytes in a sample using chromatography. The present disclosure provides methods of separating an analyte from a sample. A mobile phase is flowed through a chromatography column. The mobile phase includes about 0.005% (v/v) to about 0.20% (v/v) difluoroacetic acid and less than about 100 ppb of any individual metal impurity. A sample including the analyte is injected into the mobile phase. The analyte is separated from the sample.

A method for determining asphaltene stability in a hydrocarbon-containing material having solvated asphaltenes therein is disclosed. In at least one embodiment, it involves the steps of: (a) precipitating an amount of the asphaltenes from a liquid sample of the hydrocarbon-containing material with an alkane mobile phase solvent in a column; (b) dissolving a first amount and a second amount of the precipitated asphaltenes by changing the alkane mobile phase solvent to a final mobile phase solvent having a solubility parameter that is higher than the alkane mobile phase solvent; (c) monitoring the concentration of eluted fractions from the column; (d) creating a solubility profile of the dissolved asphaltenes in the hydrocarbon-containing material; and (e) determining one or more asphaltene stability parameters of the hydrocarbon-containing material.

A method for determining asphaltene stability in a hydrocarbon-containing material having solvated asphaltenes therein is disclosed. In at least one embodiment, it involves the steps of: (a) precipitating an amount of the asphaltenes from a liquid sample of the hydrocarbon-containing material with an alkane mobile phase solvent in a column; (b) dissolving a first amount and a second amount of the precipitated asphaltenes by changing the alkane mobile phase solvent to a final mobile phase solvent having a solubility parameter that is higher than the alkane mobile phase solvent; (c) monitoring the concentration of eluted fractions from the column; (d) creating a solubility profile of the dissolved asphaltenes in the hydrocarbon-containing material; and (e) determining one or more asphaltene stability parameters of the hydrocarbon-containing material.

This invention provides a method that is capable of detecting a trifluridine-related substance and a tipiracil-related substance contained in a sample containing trifluridine or a salt thereof and tipiracil or a salt thereof using the same procedure. The method is for detecting a trifluridine-related substance or a tipiracil-related substance or both, the method comprising the step of subjecting a sample containing trifluridine or a salt thereof and tipiracil or a salt thereof to high-performance liquid chromatography using a mobile phase composed of an organic phase and an aqueous phase.

The present invention provides the use of charged surface reversed phase chromatographic materials along with standard reversed-phase LC and mass spectrometry compatible conditions for the retention, separation, purification, and characterization of acidic, polar molecules, including, but not limited to, organic acids, -amino acids, phosphate sugars, nucleotides, other acidic, polar biologically relevant molecules. The chromatographic materials of the invention are high purity chromatographic materials comprising a chromatographic surface wherein the chromatographic surface comprises a hydrophobic surface group and one or more ionizable modifier.

The present invention is generally related to the analysis of chemical compositions of hydrocarbons and hydrocarbon blends. This method applies specifically to the problem of analyzing extremely complex hydrocarbon-containing mixtures when the number and diversity of molecules makes it impossible to realistically identify and quantify them individually in a reasonable timeframe and cost. The advantage to this method over prior art is the ability to separate and identify chemical constituents and solvent fractions based on their solvent-solubility characteristics, their high performance liquid chromatographic (HPLC) adsorption and desorption behaviors, and their interactions with stationary phases; and subsequently identify and quantify them at least partially using various combinations of non-destructive HPLC, destructive HPLC, and stand-alone detectors presently not routinely used for HPLC but reconfigured to obtain spectra on the fly. This analytical method is especially useful for, but not limited to, asphalt binders and asphalt binder blends, modified asphalts, asphalt modifiers, asphalt additives, polymer-modified asphalts, asphalts containing rejuvenators and softening agents, asphalts containing recycled products, aged asphalts, and air-blown asphalts, which may contain wide varieties of different types of additives and chemistries, and forensic applications, and environmental pollutant identification.

The present invention is generally related to the analysis of chemical compositions of hydrocarbons and hydrocarbon blends. This method applies specifically to the problem of analyzing extremely complex hydrocarbon-containing mixtures when the number and diversity of molecules makes it impossible to realistically identify and quantify them individually in a reasonable timeframe and cost. The advantage to this method over prior art is the ability to separate and identify chemical constituents and solvent fractions based on their solvent-solubility characteristics, their high performance liquid chromatographic (HPLC) adsorption and desorption behaviors, and their interactions with stationary phases; and subsequently identify and quantify them at least partially using various combinations of non-destructive HPLC, destructive HPLC, and stand-alone detectors presently not routinely used for HPLC but reconfigured to obtain spectra on the fly. This analytical method is especially useful for, but not limited to, asphalt binders and asphalt binder blends, modified asphalts, asphalt modifiers, asphalt additives, polymer-modified asphalts, asphalts containing rejuvenators and softening agents, asphalts containing recycled products, aged asphalts, and air-blown asphalts, which may contain wide varieties of different types of additives and chemistries, and forensic applications, and environmental pollutant identification.

The inventive technology may involve, in particular embodiments, novel use of a non-porous, high surface energy stationary phase to adsorb, in reversible fashion, the most polar component of a resins fraction of an input hydrocarbon when a mobile phase is passed over the stationary phase. Such reversible adsorption prevents irreversibly adsorption of such components on active stationary phase(s) downflow of the non-porous, high surface energy stationary phase, thereby conserving stationary phase costs and increasing resolution of resins elutions, and accuracy of hydrocarbon component results. Aspects of the inventive technology may also involve a novel combination of a solubility based asphaltene component fractionating and analysis method and an adsorption chromatography method for separating and/or analyzing saturate, aromatics and resins components of an input hydrocarbon.