Learn

Learning Center

These pages explain laboratory documents and analytical terms used when reading a research peptide certificate of analysis. They are written for lab work. They are not product pages, and they give no instructions for use in people or animals.

For research use only. Not for human or animal consumption.

Illustration of a clean paper certificate with a navy seal

Certificates

What is a certificate of analysis?

A certificate of analysis is a lab's report on one batch of material. What it contains, who issues it, and how it differs from a spec sheet.

COABasics

Read article

Illustration of a lab report sheet with a test table and a small peak chart

Certificates

How to read a peptide certificate of analysis

A walk through a peptide certificate of analysis from header to signature: sample block, test table, chromatogram and mass spectrum.

COAReading a report

Read article

Illustration of a magnifying glass over a document with a misaligned stamp

Certificates

How to spot an altered or reused certificate of analysis

The patterns that show up when a certificate of analysis has been edited, recycled across lots or cropped.

COADocument checks

Read article

Illustration of a stylized bacterial cell wall membrane

Endotoxin

What are endotoxins, and why do they show up on a COA?

Endotoxins are fragments of bacterial cell walls that survive purification. What they are and how labs measure them.

EndotoxinCOA

Read article

Illustration of a chart with a smooth line rising into several peaks

Chromatography

What is a chromatogram?

A chromatogram is the chart a separation produces: signal against time, one peak per component.

HPLCChromatogram

Read article

Illustration of a chart with one tall main peak and two small peaks

Chromatography

What an HPLC purity figure means

HPLC purity is an area percent under one method. The formula, a worked example, and what a single figure does and does not say.

HPLCPurity

Read article

Illustration of a balance scale comparing chart bars with a reference block

Chromatography

Purity vs assay on a lab report

Purity is a relative share of peak area. Assay is a measured amount against a reference standard.

PurityAssay

Read article

Illustration of a stopwatch whose face shows a single chromatogram peak

Chromatography

What is retention time?

Retention time is when a compound comes off the column. What sets it, why it shifts, and why it can only be compared within one method.

HPLCRetention time

Read article

Illustration of chart peaks showing tailing, splitting and overlap

Chromatography

Split, tailing and overlapping peaks: reading odd peak shapes

What tailing, fronting, split and overlapping peaks look like on an HPLC chromatogram, and what usually causes them.

HPLCPeak shape

Read article

Illustration of a chain of spheres with a small spark and a clump of loose spheres

Chromatography

Degradation, oxidation and aggregation: how they show up in the data

How oxidation, deamidation, hydrolysis and aggregation change a peptide, and where each one tends to show up in the data.

StabilityHPLCMass spec

Read article

Illustration of a peak chart beside a bar spectrum

Mass spec

HPLC vs mass spectrometry: two questions, two tests

HPLC says how much of a sample is one component. Mass spec says what that component is.

HPLCMass spec

Read article

Illustration of a column linked to a detector module showing a bar spectrum

Mass spec

HPLC vs LC-MS: same separation, different detector

LC-MS is HPLC with a mass spectrometer as the detector. What that adds, and why purity usually still comes from the UV trace.

HPLCLC-MS

Read article

Mass spec

How mass spectrometry confirms a peptide's identity

How a mass spectrometer turns a peptide into ions, why one peptide shows several peaks, and how a lab matches mass to sequence.

Mass specIdentity

Read article

Illustration of a chain of spheres on a weighing platform with a bar spectrum behind it

Mass spec

Peptide molecular weight and the mass spectrum

What a peptide's molecular weight is, monoisotopic versus average mass, and how the mass spectrum on a COA checks it.

Mass specMolecular weight

Read article

Illustration of an ice crystal above a chart with a falling drying curve

Lyophilization

What is lyophilization?

Lyophilization removes water from frozen material by sublimation under vacuum. The three stages and what the cake looks like.

LyophilizationBasics

Read article

Illustration of three element tiles for lead, arsenic and cadmium

Related analysis

Heavy metals testing and ICP-MS on a certificate of analysis

How ICP-MS measures trace metals such as lead, arsenic, cadmium and mercury, and how to read an elemental impurities line.

ICP-MSMetalsCOA

Read article

Illustration of two report sheets with bar charts at different heights

Comparing reports

Why lab tests disagree: method, sample and timing

Two honest labs can test one lot and print different numbers. How method, sample and timing each move a figure.

MethodSampleTiming

Read article

Research use only

Peptira supplies materials for laboratory research. For research use only. Not for human or animal consumption. Not for diagnostic or therapeutic use. These pages explain lab documents and analytical terms. They are not medical advice.