Analytical Method¶
Definition¶
An analytical method is a documented procedure for performing a chemical or physical analysis, specifying the equipment, reagents, conditions, and calculations required to obtain a result.
Overview¶
Analytical methods are the foundation of quality testing. Each test on a COA (HPLC purity, MS identity, assay) is performed according to a validated analytical method that ensures consistent, reliable results.
Technical Explanation¶
Common Analytical Methods for Peptides:
| Method | Purpose | Key Parameters |
|---|---|---|
| RP-HPLC | Purity determination | Column, gradient, wavelength, flow rate |
| LC-MS | Identity + purity | HPLC conditions + MS parameters |
| Mass Spectrometry | Molecular weight confirmation | Ionization mode, mass range |
| Amino Acid Analysis | Composition verification | Hydrolysis, derivatization, detection |
| Karl Fischer | Water content | Titration parameters |
| LAL Test | Endotoxin detection | Sensitivity, incubation conditions |
Method Validation Parameters (ICH Q2): - Accuracy (recovery) - Precision (repeatability, intermediate precision) - Specificity (ability to measure the analyte without interference) - Detection Limit (LOD) - Quantitation Limit (LOQ) - Linearity (response vs. concentration) - Range - Robustness
Importance in Peptide Documentation¶
The analytical method used for each test is listed on the COA. Reproducibility of results depends on using consistent methods. Method changes require re-validation and may affect specification limits.
Related Terms¶
Frequently Asked Questions¶
Q: Are all peptide purity methods the same? A: No. Different peptides require different HPLC conditions (column, gradient, wavelength) optimized for their specific properties. Method transfer between labs requires verification.
Q: What is "method validation"? A: Validation demonstrates that an analytical method is suitable for its intended purpose. Validated methods provide confidence that test results are accurate and reliable.