CEI-MS-03 — procedure

§4Procedure

The procedure below is written in the second person, which is the only place in the Institute's document set where that register is used. A procedure is an instruction and is written as one.

1. Determine water content per CEI-MS-04 and record as w %.
2. Determine counter-ion identity and content per CEI-MS-10 and record as c %.
3. Determine residual solvent content per CEI-MS-12 where a solvent of concern was used in purification, and record as s %.
4. Determine peptide content by one of: quantitative assay against an assigned reference standard; amino-acid analysis after complete acid hydrolysis; or nitrogen determination with a calculated nitrogen factor. State which was used.
5. Where a reference standard is not available, calculate content by difference: content = 100 − w − c − s − (any other declared component). Record explicitly that the value was obtained by difference, since a by-difference value attributes all unaccounted mass to peptide and therefore overstates content whenever an undeclared component is present.
6. Construct the mass balance and report the residual. A residual exceeding 6 % indicates an undeclared component and is reported as such rather than absorbed into the peptide figure.
7. Report purity, content, water, counter-ion and the mass-balance residual together. The Institute does not accept a content figure presented without the balance from which it derives.

References cited on this page

References are numbered in order of first citation in this document. Each superscript in the text links to its entry below.

1. United States Pharmacopeial Convention. General Chapter ⟨1225⟩ Validation of Compendial Procedures. United States Pharmacopeia — National Formulary (USP–NF) 2024;USP 2024 Issue 1. identifier not held by the Institute

Identifiers are reproduced only where the Institute holds them. Where a digital object identifier or PubMed identifier is not shown, the Institute has recorded the journal and year and has not constructed an identifier.