Abstract: An analytical method for detecting presence of oxidizing substances by measuring degradation of peptides may include preparing a test preparation that includes a peptide and a sample. The peptide degrades in the presence of oxidizing substances. The method may include detecting impurities of the peptide in the test preparation in which detected impurities indicate presence of oxidizing substances in the sample. Examples include using high performance liquid chromatography to detect, identify, and quantify impurities of the peptide indicating presence of oxidizing substances in the sample. Exemplary oxidizing substances include peroxide-containing, chlorine-containing compounds, and bromine-containing compounds. Exemplary peptides include vasopressin.

Abstract: An analytical method for measuring degradation of iron-carbohydrate complex for intravenous injection may include formulating a reaction solution comprising an iron-carbohydrate complex for intravenous injection, a reducing agent, and a complexing agent. The method may further include measuring absorbance spectral absorbance of an iron-complexing agent species including all or a portion of the complexing agent and iron released from the iron-carbohydrate complex that has been reduced by the reducing agent. Example complexing agents may include 1,10 phenanthroline or ferrozine. An example, iron-carbohydrate complex may be iron sucrose injection.