Abstract: Labeling reagents, sets of labeling reagents, and labeling techniques are provided for the relative quantitation, absolute quantitation, or both, of ketone or aldehyde compounds including, but not limited to, analytes comprising steroids or ketosteroids and includes testosterone. The analytes can be medical or pharmaceutical compounds in biological samples. Methods for labeling, analyzing, and quantifying ketone or aldehyde compounds are also disclosed as are methods that also use mass spectrometry.

Abstract: Labeling reagents, sets of labeling reagents, and labeling techniques are provided for the relative quantitation, absolute quantitation, or both, of ketone or aldehyde compounds including, but not limited to, analytes comprising steroids or ketosteroids and includes testosterone. The analytes can be medical or pharmaceutical compounds in biological samples. Methods for labeling, analyzing, and quantifying ketone or aldehyde compounds are also disclosed as are methods that also use mass spectrometry.

Abstract: In some embodiments, this invention pertains to active esters of N-substituted piperazine acetic acid, including isotopically enriched versions thereof. In some embodiments, this invention pertains to methods for the preparation of active esters of N-substituted piperazine acetic acid, including isotopically enriched versions thereof.

Abstract: This invention pertains to methods, mixtures, kits and/or compositions for the determination of analytes by mass analysis using unique labeling reagents or sets of unique labeling reagents. The labeling reagents can be isomeric or isobaric and can be used to produce mixtures suitable for multiplex analysis of the labeled analytes.

Abstract: In various aspects, the present teachings provide labeling reagents and sets of labeling reagents for the relative quantitation, absolute quantitation, or both, of hydroxylated compounds including, but not limited to, hydroxylated ring containing compounds, steroids and sterols. In various aspects, the present teachings also provide methods for the analysis hydroxylated compounds including, but not limited to, hydroxylated ring containing compounds, steroids and sterols my MS/MS methods.

Abstract: Quantification of vitamin D2, vitamin D3, and the monohydroxy and diihydroxy metabolites of vitamin D2 and vitamin D3, can comprise labeling analytes with mass spectrometry (MS) tagging reagents and performing LC-MSMS analysis of the labeled analytes. The labeled analytes can include a labeled standard and can have distinct retention times on a reversed phase column, as well as distinct masses. Under high energy collisions, reporter groups can be generated. The intensity or the peak area detected for each reporter group can be used for quantitation. In some embodiments, a one-step tagging reagent is used that is a dienophile-containing, labeled Diels Alder reagent.

Abstract: In some embodiments, this invention pertains to isotopically enriched N-substituted piperazines. In some embodiments, this invention pertains to methods for the preparation of isotopically enriched N-substituted piperazines.

Abstract: Labeling reagents, sets of labeling reagents, and labeling techniques are provided for the relative quantitation, absolute quantitation, or both, of ketone or aldehyde compounds including, but not limited to, analytes comprising steroids or ketosteroids. The analytes can be medical or pharmaceutical compounds in biological samples. Methods for labeling, analyzing, and quantifying ketone or aldehyde compounds are also disclosed as are methods that also use mass spectrometry.

Abstract: This invention pertains to methods, mixtures, kits and/or compositions for the determination of analytes by mass analysis using unique labeling reagents or sets of unique labeling reagents. The labeling reagents can be isomeric or isobaric and can be used to produce mixtures suitable for multiplex analysis of the labeled analytes.

Abstract: In some embodiments, this invention pertains to active esters of N-substituted piperazine acetic acid, including isotopically enriched versions thereof. In some embodiments, this invention pertains to methods for the preparation of active esters of N-substituted piperazine acetic acid, including isotopically enriched versions thereof.

Abstract: In some embodiments, this invention pertains to isotopically enriched N-substituted piperazine acetic acids. In some embodiments, this invention pertains to methods for the preparation of isotopically enriched N-substituted piperazine acetic acids.

Abstract: In some embodiments, this invention pertains to isotopically enriched N-substituted piperazines. In some embodiments, this invention pertains to methods for the preparation of isotopically enriched N-substituted piperazines.

Abstract: The invention provides methods for labeling a molecule by contacting a sample molecule with a solid support coupled to a chemical group comprising a cleavable functional group, one or more functional groups, and a reactive group for the sample molecule, under conditions allowing the sample molecule to covalently bind to the reactive group; and cleaving the cleavable functional group, thereby releasing the sample molecule comprising the one or more functional groups, which can be a tag. The invention also provides a solid support covalently coupled to a chemical group comprising a cleavable functional group, a mass spectrometry tag and a reactive group for covalently attaching a sample molecule, wherein the cleavable functional group, the tag and the reactive group are positioned relative to each other to allow transfer of the tag to the sample molecule upon cleavage of the cleavable functional group.

Abstract: In some embodiments, this invention pertains to isotopically enriched N-substituted piperazine acetic acids. In some embodiments, this invention pertains to methods for the preparation of isotopically enriched N-substituted piperazine acetic acids.

Abstract: In some embodiments, this invention pertains to isotopically enriched N-substituted piperazines. In some embodiments, this invention pertains to methods for the preparation of isotopically enriched N-substituted piperazines.

Abstract: This invention pertains to methods, mixtures, kits and compositions pertaining to analyte determination by mass spectrometry.

Abstract: This invention pertains to methods, mixtures, kits and/or compositions for the determination of analytes by mass analysis using unique labeling reagents or sets of unique labeling reagents. The labeling reagents can be isomeric or isobaric and can be used to produce mixtures suitable for multiplex analysis of the labeled analytes.

Abstract: The invention provides methods for labeling a molecule by contacting a sample molecule with a solid support coupled to a chemical group comprising a cleavable functional group, one or more functional groups, and a reactive group for the sample molecule, under conditions allowing the sample molecule to covalently bind to the reactive group; and cleaving the cleavable functional group, thereby releasing the sample molecule comprising the one or more functional groups, which can be a tag. The invention also provides a solid support covalently coupled to a chemical group comprising a cleavable functional group, a mass spectrometry tag and a reactive group for covalently attaching a sample molecule, wherein the cleavable functional group, the tag and the reactive group are positioned relative to each other to allow transfer of the tag to the sample molecule upon cleavage of the cleavable functional group.

Abstract: In some embodiments, this invention pertains to isotopically enriched N-substituted piperazines. In some embodiments, this invention pertains to methods for the preparation of isotopically enriched N-substituted piperazines.

Abstract: In some embodiments, this invention pertains to isotopically enriched N-substituted piperazine acetic acids. In some embodiments, this invention pertains to methods for the preparation of isotopically enriched N-substituted piperazine acetic acids.