Key points
A narrow, evidence-based reading
- Identity asks whether a sample appears to be the named material.
- Purity describes what share of a tested sample appears to be the main component.
- Identity and purity do not answer every question about the material.
What an identity result tells you
An identity test checks whether a sample appears to be the named material. Labs may look at mass, a spectrum, chromatography, sequence information, or other features that help tell materials apart.
The details matter. One HPLC retention time alone is usually a weak way to identify a material. A lab can get a clearer answer by using more than one kind of test.
What a purity result tells you
Purity is a result from a specific test. In an HPLC report, a percentage often shows how much of the detector signal came from the main peak under that test's conditions. It does not show every possible impurity or give the exact weight of the main material.
A full purity review may need to consider related impurities, water, salts, leftover solvents, and other components. That is why a purity number needs the method and report that produced it.
Amount needs its own test
Assay or content testing measures the amount of a named component in a sample. A purity percentage alone does not confirm the amount written on a container.
When the amount matters for research, look for a test and result that measure amount. Avoid making up a content result by multiplying numbers from different tests.
Make a simple results list
A short list helps keep results straight. For each question, write down the test method, result, unit, pass requirement, sample name, and date. Leave a blank when the report does not provide the information.
- Identity
- What test evidence supports the name of the material?
- Purity
- What did the test separate or detect, and how did the lab calculate the percentage?
- Amount
- Did the lab measure the amount of the named component?
- Other details
- Did the report cover water, leftover solvents, salts, microbial contamination, endotoxin, or other relevant concerns?
Read a percentage with its report
Stay with what the test actually measured. A percentage without a named method, a clear calculation, a named sample, and the full report leaves important questions open.
This page explains research documents. It does not judge a particular material or provide medical, dosing, administration, or personal-use information.
Primary references
Source notes
These references provide analytical and documentation context. Citing them does not claim that Beach Bio Research catalog items are approved products or that the cited regulatory frameworks apply to a particular catalog item.
- Q6A Specifications: Test Procedures and Acceptance CriteriaU.S. Food and Drug Administration. Discusses identification, test procedures, specifications, and acceptance criteria.
- SI-traceable value assignment of peptide purityNational Institute of Standards and Technology. Reviews measurement approaches used to characterize and assign peptide purity.
- Q2(R2) Validation of Analytical ProceduresU.S. Food and Drug Administration. General framework for analytical-procedure validation and performance characteristics.