This disclosure provides liquid chromatography tandem mass spectrometer (LC-MS/MS) methods and systems for detecting low levels of pesticides in a test sample. In the disclosed methods and systems, an ammonium salt is added to a mobile phase added to a liquid chromatography column or to the eluant from a liquid chromatography column. This addition improves the signal for certain pesticides by a factor of from 2 to 20, improving their detection limits in a variety of test samples.

This disclosure provides liquid chromatography tandem mass spectrometer (LC-MS/MS) methods and systems for detecting low levels of pesticides in a test sample. In the disclosed methods and systems, an ammonium salt is added to a mobile phase added to a liquid chromatography column or to the eluant from a liquid chromatography column. This addition improves the signal for certain pesticides by a factor of from 2 to 20, improving their detection limits in a variety of test samples.

Systems and methods for analyzing groundwater samples with multiple organic tracer species from a petroleum containing reservoir include obtaining the sample, isolating an aqueous fraction of the groundwater sample, separating the aqueous fraction into a plurality of components, where each component corresponds to a different one of the organic tracer species, combining each of the separated components with at least one lanthanide element to form a plurality of component solutions, where a ratio of the at least one lanthanide element to the separated component in each component solution is 5:1 or greater, and analyzing each component solution to determine a relative amount of each organic tracer species in the groundwater sample.

Systems and methods for analyzing groundwater samples with multiple organic tracer species from a petroleum containing reservoir include obtaining the sample, isolating an aqueous fraction of the groundwater sample, separating the aqueous fraction into a plurality of components, where each component corresponds to a different one of the organic tracer species, combining each of the separated components with at least one lanthanide element to form a plurality of component solutions, where a ratio of the at least one lanthanide element to the separated component in each component solution is 5:1 or greater, and analyzing each component solution to determine a relative amount of each organic tracer species in the groundwater sample.

The present disclosure describes an apparatus, method, and system of regulating a detector flow of a field flow fractionator. In an embodiment, the apparatus includes (1) a detector flow meter, where the detector flow meter is configured to measure a detector flow from the field flow fractionator, (2) a channel pressure meter, where the channel pressure meter is configured to measure a channel pressure of the field flow fractionator, (3) at least one control valve, where an inlet of the at least one control valve is connected to an outlet of the channel pressure meter, (4) where the detector flow meter is configured to set a channel pressure set point of the channel pressure meter, and (5) where the channel pressure meter is configured to actuate the at least one control valve to maintain a channel pressure of the field flow fractionator at the channel pressure set point.

Methods and system for identification of dimer species using online chromatography and electrospray ionization mass spectrometry are provided. Also provided are methods and system for quantitation of heterodimer species using immunoprecipitation and liquid chromatography-mass spectrometry.

A device for separating one or more molecules of interest in a liquid specimen including a monolithic body defining a fractionation column. The column includes an inlet opening at a proximal end of the fractionation column; an outlet opening at a distal, opposite end of the fractionation column; a solid phase chamber positioned between the inlet opening and the outlet opening; a specimen introduction area adjacent a proximal end of the solid phase chamber; an analyte exit area adjacent a distal end of the solid phase chamber; an inlet chamber adjacent the inlet opening that tapers into the specimen introduction area; and an outlet chamber that extends from the analyte exit area to the outlet opening. A metered amount of solid phase packed within the solid phase chamber between a first porous frit and a second porous frit of the solid phase chamber.

A device for separating one or more molecules of interest in a liquid specimen including a monolithic body defining a fractionation column. The column includes an inlet opening at a proximal end of the fractionation column; an outlet opening at a distal, opposite end of the fractionation column; a solid phase chamber positioned between the inlet opening and the outlet opening; a specimen introduction area adjacent a proximal end of the solid phase chamber; an analyte exit area adjacent a distal end of the solid phase chamber; an inlet chamber adjacent the inlet opening that tapers into the specimen introduction area; and an outlet chamber that extends from the analyte exit area to the outlet opening. A metered amount of solid phase packed within the solid phase chamber between a first porous frit and a second porous frit of the solid phase chamber.

Systems, indicator wipe product, and methods thereof used to detect the presence of cationic polymer residues on a surface are described. In various embodiments, the cationic polymer to be detected comprises a quaternary silane residual antimicrobial. The indicator wipe may comprise a woven, nonwoven, or double-knit fabric, cotton, functional cellulose, or open cell foam material substrate impregnated with an aqueous dye solution comprising a sulfonephthalein dye. The indicator wipe may be configured to differentiate between traditional monomer quaternary ammonium compounds and cationic polymers such as quaternary silane compounds used in residual antimicrobial coatings by color changes on the indicator wipe and by observing if cationic-dye complexes diffuse by chromatography on the indicator wipe.

The present disclosure relates generally to the field of analyzing a nucleic acid, such as RNA, in particular to the determination of at least one parameter of a sample composition comprising a nucleic acid, especially RNA, and optionally particles.