Comparative study for purity assessment of recombinant human growth hormone using mass balance approach and amino acid-based isotope dilution mass spectrometry

Abstract

Growth hormone plays an unreplaceable role in regulating human growth and promoting protein synthesis, etc. For this reason, accurate quantification of its purity has become a focus of attention in the pharmaceutical industry and medical research. Herein, the purity assessment of human growth hormone (hGH) was established on the basis of mass balance approach and amino acid (AA)-based isotope dilution mass spectrometry (IDMS). In the first method, hGH purity was quantified by the determination of all the impurities in a hGH study material. In the second method, hGH purity was assessed by quantifying hydrolyzed AAs, e.g. leucine (Leu), phenylalanine (Phe), and proline (Pro). To accurately quantify these AAs, the corresponding isotope-labeled AAs were used as internal standards using high-performance liquid chromatography- mass spectrometry (HPLC-MS). The results of the two methods for determining the purity of hGH were consistent, with the mass balance method giving a result of (0.352 ± 0.010) g/g and IDMS a result of (0.363 ± 0.028) g/g. The work in this study could give a benefit for protein quantification and provides a reference for the development of hGH certified reference materials.