Thyroxine-Containing Compound Analysis Methods

A method for analyzing one or more of thyroxine compounds in one or more samples, wherein the thyroxine compounds can be represented by the general formula (IV):

• wherein each of R1 is independently iodine or hydrogen;
• and
• R2 is carboxyl, hydroxyl or methyl
• comprising the steps of:
• labeling one or more thyroxine compounds each with a different isobaric tag from a set of isobaric tags;
• combining at least a portion of each of the isobarically labeled thyroxine compounds to produce a combined sample;
• loading at least a portion of the combined sample on a chromatographic column;
• subjecting at least a portion of the eluent from the chromatographic column to parent-daughter ion transition monitoring wherein, the transmitted parent ion m/z range includes a m/z value of one or more of the isobarically labeled thyroxine compounds and the transmitted daughter ion m/z range includes a m/z value of at least one reporter ion corresponding to at least one of the isobaric tags of the isobarically labeled thyroxine compounds;
• and
• measuring the ion signal of one or more of the transmitted reporter ions;
• and
• 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 a concentration curve of a standard compound.

A method for analyzing one or more of thyroxine compounds in one or more samples, wherein the thyroxine compounds can be represented by the general formula (IV):

• wherein each of R1 is independently iodine or hydrogen;
• and
• R2 is carboxyl, hydroxyl or methyl
• comprising the steps of:
• labeling one or more thyroxine compounds each with a different isobaric tag from a set of isobaric tags;
• combining at least a portion of each of the isobarically labeled thyroxine compounds to produce a combined sample;
• subjecting at least a portion of the combined sample to parent-daughter ion transition monitoring using matrix assisted laser desorption ionization wherein, a first transmitted parent ion m/z range includes a m/z value of one or more of the isobarically labeled thyroxine compounds and a first transmitted daughter ion m/z range includes a m/z value of at least one reporter ion corresponding to at least one of the isobaric tags of the isobarically labeled thyroxine compounds;
• measuring the ion signal of one or more of the transmitted reporter ions;
• and
• 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 the measured ion signal of a standard compound comprising a thyroxine compound.