HPLC Purity vs. LC-MS Identity: What Buyers Should Verify

01

Begin with the question each test is intended to answer

A buyer often sees an HPLC percentage beside a mass spectrum and assumes that the two records confirm the same claim. They do not.

Chromatography can describe the relative pattern detected under defined separation and detection conditions. Mass spectrometry can provide mass information that supports identity. Both require sample and method context.

02

Do not read a purity percentage without the chromatogram

A percentage should be connected to the chromatogram, sample identifier, detection approach, integration and method conditions. The number alone does not show unresolved peaks, ignored regions or compounds that are not detected under the method.

The chromatographic result also should not be confused with net peptide content, total vial weight or identity.

03

Use mass information to support identity—not every quality attribute

An observed mass consistent with the expected peptide can support identity, but it does not by itself describe chromatographic purity, counter-ion content, water, residual solvents, sterility or every possible impurity.

Ask whether the report shows the expected mass, observed mass, charge-state or deconvolution context, sample reference and conclusion.

04

Match both records to the same sample or batch

The HPLC record and mass result are most useful when both can be traced to the same sample or batch offered to the buyer.

If one record is only a representative example, it should be labeled as an example rather than presented as evidence for the offered batch.

05

Review method suitability and system context

ICH Q2(R2) states that analytical procedure validation demonstrates suitability for the intended purpose and discusses characteristics such as specificity or selectivity, accuracy, precision and reportable range.

A buyer usually will not receive a full method-validation package for every research order, but can still ask which method was used, whether it is established for the intended report and whether system-suitability information is available when required.

06

Keep acceptance criteria separate from observed results

The specification states the acceptance criterion. The record states the result. The COA should not turn one into the other.

For regulated APIs within scope, FDA guidance connects analytical procedures and acceptance criteria to the intended specification. For other B2B products, the parties should still agree on what result is required before ordering.

07

Ask whether testing is internal or independent

Internal testing can be part of the manufacturer’s quality workflow. Independent testing can add separation between supplier and tester. Both should identify the sample, method and issuer honestly.

A third-party report does not prove another batch and should not be reused outside its sample context.

08

Write the analytical request into the RFQ

Specify whether you require a batch COA, HPLC chromatogram, MS or LC-MS record, third-party testing or another attribute. State when the record must be available.

Stablize Peptides confirms HPLC, MS and other documentation only for eligible products and orders. A specification is not presented as a tested batch result without a corresponding record.

RELATED GUIDANCE

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