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 present teachings provide methods for analyzing one or more thyroxine compounds in one or more samples using isobaric labels and parent-daughter ion transition monitoring (PDITM). In various embodiments, the methods comprise the steps of: (a) labeling one or more thyroxine compounds with different isobaric tags from a set of isobaric tags, each isobaric tag comprising a reporter ion portion; (b) combining at least a portion of each of the isobarically labeled thyroxine compounds to produce a combined sample; (c) subjecting at least a portion of the combined sample to PDITM; (d) measuring the ion signal of one or more of the transmitted reporter ions; and (e) determining the concentration of one or more of the isobarically labeled thyroxine compounds based at least on a comparison of the measured ion signal of the corresponding reporter ion to one or more measured ion signals of a standard compound.

Abstract: This invention pertains to isobarically labeled analytes and fragment ions thereof.

Abstract: The present teachings provide methods for analyzing one or more amine-containing compounds in one or more samples using isobaric labels and parent-daughter ion transition monitoring (PDITM). In various embodiments, the methods comprise the steps of: (a) labeling one or more amine-containing compounds with different isobaric tags from a set of isobaric tags, each isobaric tag comprising a reporter ion portion; (b) combining at least a portion of each of the isobarically labeled amine-containing compounds to produce a combined sample; (c) subjecting at least a portion of the combined sample to PDITM; (d) measuring the ion signal of one or more of the transmitted reporter ions; and (e) determining the concentration of one or more of the isobarically labeled amine-containing compounds based at least on a comparison of the measured ion signal of the corresponding reporter ion to one or more measured ion signals of a standard compound.

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: This invention pertains to methods, mixtures, kits and compositions pertaining to analyte determination by mass spectrometry using labeling reagents that comprise a nucleophilic reactive group that reacts with a functional group of an analyte to produce a labeled analyte. The labeling reagents can be used as isobaric sets, mass differential labeling sets or in a combination of isobaric and mass differential labeling sets.

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 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: 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: The present teachings provide methods for analyzing one or more thyroxine compounds in one or more samples using isobaric labels and parent-daughter ion transition monitoring (PDITM). In various embodiments, the methods comprise the steps of: (a) labeling one or more thyroxine compounds with different isobaric tags from a set of isobaric tags, each isobaric tag comprising a reporter ion portion; (b) combining at least a portion of each of the isobarically labeled thyroxine compounds to produce a combined sample; (c) subjecting at least a portion of the combined sample to PDITM; (d) measuring the ion signal of one or more of the transmitted reporter ions; and (e) determining the concentration of one or more of the isobarically labeled thyroxine compounds based at least on a comparison of the measured ion signal of the corresponding reporter ion to one or more measured ion signals of a standard compound.

Abstract: The present teachings provide methods for analyzing one or more amine-containing compounds in one or more samples using isobaric labels and parent-daughter ion transition monitoring (PDITM). In various embodiments, the methods comprise the steps of: (a) labeling one or more amine-containing compounds with different isobaric tags from a set of isobaric tags, each isobaric tag comprising a reporter ion portion; (b) combining at least a portion of each of the isobarically labeled amine-containing compounds to produce a combined sample; (c) subjecting at least a portion of the combined sample to PDITM; (d) measuring the ion signal of one or more of the transmitted reporter ions; and (e) determining the concentration of one or more of the isobarically labeled amine-containing compounds based at least on a comparison of the measured ion signal of the corresponding reporter ion to one or more measured ion signals of a standard compound.

Abstract: This invention pertains to mixtures of isobarically labeled analytes and fragment ions 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: This invention pertains to isobarically labeled analytes and fragment ions thereof.

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 mixtures of isobarically labeled analytes and fragment ions thereof.