This is a working overview of Mass spectrometry, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-01-24 and is reviewed periodically as new material appears.
Orthogonal methods reduce the chance that a single technique misses an impurity. Capillary electrophoresis separates by charge-to-size ratio and can resolve variants that co-elute under one set of HPLC conditions. Amino acid analysis reports composition after hydrolysis and confirms the presence of expected residues. Karl Fischer titration measures water content, while ion chromatography can quantify counterions. No single number captures all aspects of sample quality, so reports often combine several measurements.
Peptide purity testing uses separation methods to estimate the proportion of a sample that corresponds to the target sequence. Reverse-phase high-performance liquid chromatography is the most common technique, separating peptides by hydrophobicity on a nonpolar column. Ultraviolet detection at 214 nm records peptide bonds and aromatic residues. The resulting chromatogram is reported as area percent, which reflects relative absorbance rather than absolute mass. This distinction matters because water, counterions, and residual solvents do not appear in the peptide peak.
Mass spectrometry provides an identity check that complements chromatographic purity. Electrospray ionization or matrix-assisted laser desorption/ionization measures the mass-to-charge ratio of intact peptides. A match to the expected molecular mass supports correct sequence length and terminal groups. Mass accuracy alone does not prove that every peak in a liquid chromatogram is the target peptide. It also does not directly quantify how much water or counterion remains in a lyophilized powder.
Quality control relies on predefined specifications rather than a single purity number. A certificate of analysis typically lists the test method, acceptance limit, and measured result for each attribute. Common specifications include appearance, peptide content, water content, counterion identity, and related substances. Limits are set according to the peptide's intended use and the capability of the analytical method. A result outside a limit triggers investigation, not automatic rejection, because method variability and sample handling can affect outcomes.
Sample handling influences measured purity. Lyophilized peptides are hygroscopic and can absorb water, changing weight-based calculations, while repeated freeze-thaw cycles may promote aggregation or degradation. Dissolved samples should be prepared fresh when possible and protected from light and heat. In purity testing, the same handling conditions should apply to standards and samples. Stability-indicating methods are designed to separate degradation products from the parent peptide, though open questions remain about how accelerated stability data predict long-term behavior for every sequence.
| Property | Value | Notes |
|---|---|---|
| Primary purity method | Reverse-phase HPLC | Separates peptides by hydrophobicity; reports area percent. |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI; matches observed mass to expected sequence. |
| Orthogonal separation | Capillary electrophoresis | Separates by charge-to-size ratio; complements HPLC. |
| Water content | Karl Fischer titration | Water dilutes peptide mass and affects concentration calculations. |
| Counterion | Trifluoroacetate or acetate | Common counterions alter net peptide content in lyophilized powder. |
=== Familiäres Mittelmeerfieber === Colchicin ist ein Grundpfeiler in der Behandlung des familiären Mittelmeerfiebers (FMF). Es wirkt sich nachweislich positiv auf Häufigkeit der Attacken aus und senkt das Amyloidoserisiko. Amyloidose entsteht durch eine Anhäufung des Proteins Serum Amyloid A im Körper. Dies führt zu einer Proteinurie (erhöhte Ausscheidung von Protein im Urin), welche unbehandelt zu Nierenversagen führt. Eine langsame Dosissteigerung kann abhängig vom klinischen Beschwerdebild, Entzündungsparametern und ggf. beim Vorliegen einer Amyloidose erfolgen. Die kontinuierliche tägliche Einnahme von Colchicin reduziert die Proteinurie bei Patienten mit einer Amyloid-Nierenerkrankung und verlangsamt den Fortschritt einer chronischen Niereninsuffizienz.
=== Zirrhose === Auch wenn sich im Tierversuch die Faserbildung in der Leber durch die Verabreichung von Colchicin hemmen lässt, konnte bei einer klinischen Studie an 55 Patienten mit histologisch gesicherter alkoholischer Leberzirrhose keine signifikante Besserung gegenüber einer Placebogruppe festgestellt werden. Die Beobachtungszeit betrug mehr als 40 Monate. Die Nebenwirkungen waren tolerabel.
=== Morbus Behçet === Beim Morbus Behçet konnten in verschiedenen Studien, insbesondere bei Kindern, positive Ergebnisse erhalten werden. Im Vergleich zu Steroiden oder Immunsuppressiva scheint Colchicin vorteilhaft aufgrund der besseren Langzeitverträglichkeit.
=== SARS-CoV-2-Infektion === Bei stationär behandelten Menschen mit moderater bis schwerer COVID-19-Erkrankung hat Colchicin nach aktueller Forschung einen geringen bzw. keinen Nutzen. Ähnliche Wirkungen zeigen sich bei leicht erkrankten Patienten mit fast keinen Symptomen. Zu Beginn der Corona-Situation wurden verschiedene antiinflammatorische Therapieansätze mit Colchicin in der COVID-19-Behandlung in klinischen Studien untersucht. Die Ergebnisse einer Studie zeigen, dass Colchicin bei Patienten mit einer PCR-bestätigten SARS-Cov-2-Infektion das Risiko für Tod oder Hospitalisierung geringfügig und knapp signifikant reduzieren kann.
Sources: de.wikipedia.org
It measures the relative ultraviolet absorbance area of peptide peaks, usually at 214 nm. It does not directly measure mass, water, counterions, or co-eluting species.
HPLC and mass spectrometry answer different questions: HPLC estimates separation purity, while mass spectrometry confirms molecular mass. Orthogonal methods reduce the risk that one technique misses an impurity.
Yes. Area percent excludes water, counterions, residual solvents, and any species that co-elute with the target peak. Net peptide content can therefore be lower than the reported HPLC purity.
A related substance is a peptide-like impurity that resembles the target sequence, such as a truncated or modified form. It is often reported as individual and total area percent.