The study compared four ways to measure how much thymosin‑alpha‑1 is in a sample and found that the elemental (CHN) analysis is the most consistent, giving less than 2% variation. Other methods like amino‑acid analysis and HPLC gave mixed results depending on the lab, while the Kjeldahl method was also evaluated but not highlighted as best. For anyone making or checking their own thymosin‑alpha‑1 doses, using CHN analysis will give the most reliable potency numbers.

Precise determination of the peptide content in drug substance samples depends highly upon the particular peptide compound and methodology used. Four independent methods were evaluated and compared to determine which would produce the best experimental precision for analysis of thymalfasin (thymosin alpha-1). Four different methods were evaluated including elemental analysis (CHN), quantitative amino acid analysis (AAA), high-performance liquid chromatography (HPLC), and Kjeldahl. This study demonstrates that the AAA method is highly variable in one laboratory while quite precise in another laboratory. Similarly, HPLC results depended on the laboratory conducting the study with more precise values obtained under cGMP. On the contrary, the CHN method yielded highly precise [i.e. <2% coefficient of variation (CV)] values. As precise knowledge of protein content is fundamental for the compounding of final pharmaceutical product of a specific potency, the CHN analysis is recommended for peptide content determination of the drug substance thymalfasin.