CEI-MS-19 — 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 the retention factor of the analyte under CEI-MS-01 conditions. Where k is below 1.0, that method is not applicable and this standard applies.
2. Select a mechanism. For a small basic peptide, ion-pairing reverse phase. For a small acidic or highly polar peptide, hydrophilic-interaction chromatography. For a very short peptide with sequence-scrambled isomers to resolve, ion-exchange or a mixed-mode phase.
3. Optimise for a retention factor between 2 and 10 for the main peak.
4. Demonstrate that the method separates the analyte from at least two known related substances with resolution ≥ 1.5. Where authentic impurity standards are unavailable, generate them by forced degradation under CEI-MS-13.
5. Confirm that the injection disturbance is fully resolved from the main peak, and state the retention time of both.
6. Determine purity as in CEI-MS-01, with the integration window stated.
7. Report the mechanism used, the retention factor achieved, and the resolution demonstrated against known related substances.

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. European Directorate for the Quality of Medicines & HealthCare. General Chapter 2.2.29 Liquid Chromatography. European Pharmacopoeia 2023;11th edition. 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.