CEI-MS-08 — 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. Select the approach: intact-peptide enantioselective chromatography where the diastereomers are resolvable, or chiral amino-acid analysis where they are not.
2. For chiral amino-acid analysis, hydrolyse in vapour-phase 6 M hydrochloric acid at 110 °C for 24 hours under vacuum. Record that tryptophan is destroyed and cysteine is partly destroyed under these conditions, and that serine and threonine racemise measurably during hydrolysis itself.
3. Run a control peptide of known all-L configuration through the identical procedure and determine the hydrolysis-induced racemisation blank for each residue.
4. Derivatise and separate. Determine the D-to-L ratio for each residue.
5. Subtract the hydrolysis blank determined on the control. Report the corrected D content per residue.
6. For a peptide designed to contain D-residues, invert the calculation: the target configuration is the expected majority and the L-form is the impurity.
7. Report each residue position assessed, the corrected D or L content, and the hydrolysis blank applied.

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. International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. ICH Q2(R2) Validation of Analytical Procedures. ICH Harmonised Guideline 2023;Step 4 version, 1 November 2023. identifier not held by the Institute

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