Determination of Isotopic Purity by Accurate Mass LC/MS

This technical report outlines the process for determining the isotopic purity of compounds synthesized at Almac Sciences using mass spectrometry. The document describes the challenges associated with analyzing isotopic labeled active pharmaceutical ingredients (APIs) that contain various labeled atoms, such as 13C, 15N, and 2H. It details the methodology employed, including the use of time of flight (TOF) mass spectrometry to enhance resolution between isotopes, allowing for accurate quantification of isotopic enrichment. The report presents a case study involving a compound with two 13C and two 15N atoms, detailing the workflow for impurity isolation and structure elucidation. The data processing steps are explained, including the removal of natural isotopic contributions and the calculation of isotopic ratios. Results indicate that 96.17% of the compound was fully enriched, with a total isotopic purity of 98.84%. The conclusion emphasizes the effectiveness of mass spectrometry in quantifying isotopic enrichment and the advantages of TOF-LC/MS in reducing erroneous results.