Peptide Lab Results & COAs | LC-MS/MS Testing

Understanding COA Reports: What Lab Results Should Confirm

A Certificate of Analysis should provide more than a purity percentage. It should identify the tested sample, confirm the lot number, describe the analytical methods used, and provide evidence that the material tested is consistent with the intended compound.

The research peptide market has become increasingly saturated with incomplete reports, recycled COAs, misleading claims, and unverifiable testing. Some reports may look legitimate but still fail to confirm identity, purity, net content, or lot-specific traceability.

This guide is designed to help readers understand what a COA should show and how to evaluate whether the report provides meaningful analytical support. The interactive example below highlights the key sections to review, including HPLC purity analysis, LC-MS identity confirmation, chromatogram interpretation, and mass confirmation.

COA Archive

Looking for Batch-Specific Test Reports?

MEDPEP maintains an ongoing COA archive where current and historical Certificates of Analysis can be reviewed by product, batch number, testing lab, report date, purity, and mass results.

Click here to view the COA archive

MedPep Lab Results

How to Read a COA Testing Report

Hover over each highlighted section of the report to understand what the result means, what the testing can confirm, and how to evaluate whether the COA is traceable and analytically meaningful.

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Testing Method Matters

Why LC-MS Matters for Peptide Identity

Purity alone does not confirm identity. A sample can show a strong purity result while still requiring additional analytical support to confirm that the material matches the intended compound.

What UV-Vis Can Show

UV-Vis testing measures how much light a sample absorbs at selected wavelengths. It can be useful as a supporting tool, but it does not confirm molecular identity on its own.

Can show absorbance patterns
May support concentration or purity review
Does not confirm molecular mass
Does not reliably identify structural variants
Cannot prove the compound is the intended peptide

What LC-MS Can Confirm

LC-MS combines liquid chromatography with mass spectrometry. This allows the sample to be separated and then evaluated by molecular mass, giving stronger evidence that the detected material is consistent with the intended peptide.

Supports molecular identity confirmation
Detects mass differences in related compounds
Helps identify degradation products or variants
Provides stronger batch-specific verification
Adds analytical support beyond purity percentage alone

The Key Difference

UV-Vis can indicate that a sample absorbs light in a certain way, but it does not prove what the molecule is. LC-MS provides mass-based evidence that helps confirm whether the tested material is consistent with the expected compound. For peptide testing, this makes LC-MS an important part of responsible batch verification.

Full LC-MS/MS Example

Why Full LC-MS/MS Testing Matters

LC-MS/MS is one of the strongest analytical tools for supporting peptide identity because it combines chromatographic separation with mass-based detection. Instead of relying only on a purity percentage, LC-MS/MS can help confirm whether the detected material appears at the expected retention time and produces the expected mass-based ion signals.

A purity result alone can look impressive while still leaving important questions unanswered. If a vendor does not provide LC-MS/MS or equivalent identity-supporting data, their documentation should be treated as incomplete. A product should not be evaluated on a purity percentage alone.

Interactive Report Example

Sidechain Analytics LC-MS/MS Report

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About “100.00%” purity: A reported value of 100.00% should be read as a very high chromatographic purity result under the stated method, not as a claim that the sample is absolutely perfect or free of every possible impurity. In practice, the calculated result may round to the displayed decimal places when no reportable secondary peaks are detected above the method’s criteria. That is why purity should still be reviewed alongside LC-MS/MS identity support, retention time, mass-based signals, and qualifier transitions.

LC-MS/MS

Identity

What is it?

Identity testing helps confirm whether the material detected in the sample is consistent with the expected peptide. For peptide analysis, LC-MS/MS provides mass-based support by monitoring signals that are specific to the compound being tested.

In a triple-quadrupole LC-MS/MS method, the instrument can monitor selected precursor-to-product ion transitions. In simpler terms, the expected molecule is selected, fragmented in a controlled way, and the resulting fragment signals are checked against the method criteria.

When the expected transitions appear at the correct retention time, they provide stronger analytical evidence that the chromatographic peak is associated with the intended peptide.

LC-MS/MS

Retention Time

Why does it matter?

Retention time shows when a compound appears during chromatographic separation. When a tested sample produces a peak at the expected retention time, it adds another layer of support that the detected signal is consistent with the intended material.

Retention time does not confirm identity by itself. However, when it is reviewed together with LC-MS/MS ion transitions, mass-based data, and chromatographic peak shape, it helps strengthen the overall interpretation of the result.

LC-MS/MS

Quantifier & Qualifier Ions

Why are multiple ion signals useful?

LC-MS/MS methods often monitor more than one ion transition for the same compound. The quantifier ion is usually the main signal used for measurement, while qualifier ions provide additional support that the detected signal is consistent with the expected peptide.

This is important because a single signal can sometimes be misleading if another compound produces a similar response. By checking multiple transitions at the expected retention time, LC-MS/MS provides stronger support than relying on one peak alone.

When the quantifier and qualifier signals match the expected method criteria, they help support the conclusion that the detected chromatographic peak is associated with the intended compound.

LC-MS/MS

Purity

How clean is it?

Purity testing helps estimate how much of the detected chromatographic signal is associated with the intended compound compared with other detected peaks in the sample.

A high purity result can be useful, but it does not confirm identity by itself. A report should still include supporting evidence such as mass-based confirmation, retention time review, and appropriate LC-MS/MS transition data.

Purity should be interpreted as one part of the full analytical picture, not as the only indicator of batch verification.

LC-MS/MS

Mass

Does the mass match?

Mass confirmation compares the measured molecular mass of the detected compound against the expected mass of the intended peptide. When the measured mass is consistent with the expected value, it provides important support for compound identity.

This matters because related compounds, fragments, degradation products, or modified variants may produce different mass signals. LC-MS/MS helps identify whether the detected material matches the expected mass profile.

Mass data is strongest when reviewed together with retention time, chromatographic peak quality, and quantifier and qualifier ion transitions.

Additional Screening

Contaminant Testing Beyond LC-MS/MS

LC-MS/MS is used to support peptide identity, mass-related confirmation, and analytical interpretation of the target compound. However, some contaminants are assessed using different specialized methods. Heavy metal screening and endotoxin testing provide additional quality documentation by looking for contamination risks that are not fully answered by identity or purity data alone.

ICP-MS Trace Element Screening

Heavy Metals

Is it contaminant-screened?

Heavy metal testing screens for trace metallic elements that may be introduced through raw materials, manufacturing equipment, reagents, handling, or environmental exposure.

This type of screening is commonly performed using ICP-MS, which stands for Inductively Coupled Plasma Mass Spectrometry. ICP-MS is designed to detect very small quantities of metals, often reported in units such as µg/g or ppm.

Common panel examples Copper, iron, nickel, arsenic, lead, cadmium, and mercury may be included depending on the test panel.

What it supports Helps document whether selected metals were detected above the reporting limits of the test.

How it relates This is separate from peptide identity testing. A product can match identity expectations and still require contaminant screening.

LAL / TAL Endotoxin Screening

Endotoxin

Is it biologically contaminant-screened?

Endotoxin testing screens for bacterial endotoxins, which are components associated with the outer membrane of certain Gram-negative bacteria. These contaminants are not identified by standard peptide purity or mass data.

Endotoxin screening is commonly performed using methods such as LAL or TAL testing. Depending on the method selected, the result may be reported as a qualitative pass/fail screen or as a quantitative result against a defined sensitivity or limit.

Common method examples Gel-clot, chromogenic, or turbidimetric formats may be used depending on the test setup.

What it supports Helps determine whether endotoxin is detected above the selected method sensitivity or reporting threshold.

How it relates This complements LC-MS/MS by screening for a biological contaminant rather than confirming peptide identity.

Transparency Standard

What We Aim to Show on Every Batch

Lab results should give customers more than a single purity percentage. A useful report should help confirm what the material is, how it was evaluated, whether the mass is consistent with the expected compound, and whether additional quality checks have been completed where appropriate.

Many peptide vendors provide only partial documentation, such as a standalone purity result with limited identity support, no clear batch traceability, or no supporting method context. That leaves important questions unanswered. Our goal is to provide clearer documentation so each batch can be reviewed with more confidence and transparency.

Core Testing Panel

Identity

LC-MS/MS identity support helps confirm that the detected material is consistent with the expected peptide by reviewing mass-based signals, ion transitions, and retention time.

Purity

Purity review helps estimate how much of the detected chromatographic signal is associated with the intended compound compared with other detected peaks.

Mass

Mass confirmation compares the measured molecular mass against the expected peptide mass, helping support the conclusion that the detected compound matches the intended material.

Our batch commitment: We will run this core testing panel with every new batch purchase so our lab documentation includes identity, purity, and mass-related confirmation instead of relying on one isolated number.

Additional QA/QC Screening

Heavy Metals

ICP-MS

Heavy metal screening checks for selected trace elements that may be introduced through raw materials, processing, handling, or environmental exposure. This testing is separate from LC-MS/MS identity work and helps document whether selected metals are detected above the reporting limits of the test.

Endotoxin

LAL / TAL

Endotoxin screening checks for bacterial endotoxins, which are not answered by peptide identity, purity, or mass data. This type of testing provides additional contamination-related quality documentation using a method such as LAL or TAL testing.