Description

L-Thyroxine-13C9,15N is a stable isotope-labeled analog of the essential thyroid hormone, levothyroxine, specifically enriched with carbon-13 and nitrogen-15. This compound is a critical tool for quantitative mass spectrometry, enabling highly accurate and sensitive measurement of endogenous thyroxine levels in complex biological matrices. It is primarily required by pharmaceutical research laboratories, clinical diagnostics developers, and contract research organizations (CROs) for use as an internal standard in LC-MS/MS assays.

Application

• Primary internal standard for the precise quantification of levothyroxine (T4) in bioanalytical methods using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS).
• Critical component in the development and validation of clinical diagnostic tests for thyroid function, including assays for hypothyroidism and hyperthyroidism.
• Used in pharmaceutical R&D for pharmacokinetic (PK) and pharmacodynamic (PD) studies of thyroid hormone formulations and related therapeutics.
• Essential for metabolic and endocrine research, facilitating studies on thyroid hormone biosynthesis, transport, and degradation pathways.
• Supports high-throughput screening in clinical laboratories for accurate and reliable patient thyroid panel results.
• Applied in forensic and anti-doping analysis for the definitive identification and measurement of thyroid hormones.

Basic Information

Product Name	L-Thyroxine-13C9,15N
CAS No.	1431868-11-9
Molecular Formula	C1513C9H1115N I4O4
Molecular Weight	~790.96 g/mol
Synonyms	Levothyroxine-13C9,15N; Thyroxine-13C9,15N; T4-13C9,15N; 3,5,3',5'-Tetraiodo-L-thyronine-13C9,15N; (2S)-2-Amino-3-[4-(4-hydroxy-3,5-diiodophenoxy)-3,5-diiodophenyl]propanoic-13C9,15N acid; Stable Isotope Labeled L-Thyroxine; L-Thyroxine (13C9, 15N); Isotopic Internal Standard for Thyroxine
EINECS	Contact for details

Quality Control

Our L-Thyroxine-13C9,15N is manufactured under strict quality systems to ensure the high isotopic purity and chemical integrity required for trace-level quantitative analysis. Each batch is accompanied by a comprehensive Certificate of Analysis (COA) detailing parameters such as isotopic enrichment, chemical purity, and absence of interfering impurities. We support compliance with GLP and GMP guidelines for research and diagnostic applications.

Storage

Preserve in a tightly closed container, protected from light. Store at -20°C or below in a dry environment. This product is hygroscopic (moisture-sensitive). Allow the sealed vial to equilibrate to room temperature before opening to minimize moisture condensation.

Specification

Item	Specification
Appearance	White to off-white solid
Identification (HPLC-MS)	Conforms
Isotopic Enrichment	≥ 99 atom % 13C; ≥ 99 atom % 15N
Chemical Purity (HPLC)	≥ 98.0%
Single Largest Unknown Impurity (HPLC)	≤ 0.5%
Water Content (KF)	≤ 1.0%

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.