How Do You Read HPLC Results on a Certificate of Analysis?
Short answer
Start with the header: confirm the sample name, lot and labeled strength match your product. Then read each test line: the method, the result with its units, and the specification it is judged against. For HPLC, identity means the main peak matches the reference standard, potency is a percent of label claim, and purity covers any extra peaks.
What’s on an HPLC certificate of analysis
A certificate of analysis (COA) summarizes what a lab found in your sample. Formats differ, but the federal rule for drug-manufacturing lab records makes a good checklist: a sample description with lot and dates, each method used, the complete data including chromatograms, calculations, results compared with the specification, and sign-off by the analyst and a second reviewer (21 CFR 211.194).
| Section | What it tells you | What to check |
|---|---|---|
| Sample information | Product, lot, labeled strength, date received | Matches your container |
| Method | HPLC-UV, LC-MS or other procedure | Named for every result |
| Reference standard | Known material the sample is compared with | Matches the labeled ingredient |
| Results | Identity, potency, purity | Units are stated |
| Specification | Acceptance criterion for each result | A limit beside each result |
| Sign-off | Analyst, reviewer, report date | A second person reviewed it |
How to read the chromatogram
A chromatogram is a graph of the detector’s signal over time. The flat line is the baseline, and each peak is the detector’s response to a different compound as it leaves the column (Waters). Time runs along the bottom, usually in minutes. Compounds that interact more strongly with the column packing come out later (Shimadzu).
- Retention time is when a peak appears. If your sample’s main peak appears at the same time as the reference standard’s peak, that supports identity.
- Peak area is the size of the peak. Compared with the area of a reference standard of known concentration, it gives the amount present.
- Other peaks may be excipients, preservatives, impurities or degradation products.
Identity, potency and purity results explained
- Identity is often reported as “conforms.” HPLC compares retention time; LC-MS testing adds molecular mass when confirmation is needed.
- Potency (assay) is reported as a percent of label claim. A capsule labeled 10 mg that measures 9.7 mg is 97% of label claim.
- Purity (related substances) lists the other peaks, often as a percentage of the main peak area. For new drug products, ICH Q3B sets thresholds above which degradation products should be reported, identified and qualified (FDA Q3B(R2)).
- “ND” or “<LOQ” means not detected, or below the method’s quantitation limit: the lowest amount it can measure with acceptable accuracy and precision. It does not mean zero. ICH Q2(R2) covers how these limits are established (FDA Q2(R2)).
Pass or fail comes from the specification
A result only means something next to its acceptance criterion. ICH Q6A describes a specification as a list of tests, analytical procedures and acceptance criteria that a product should meet (FDA Q6A). Limits differ by product, so there is no single “good” number. We report analytical results; whether a product is right for a patient is a question for the pharmacist or prescriber.
Red flags on a certificate of analysis
- No lot number or test date
- No method or units
- No specification beside the results
- Potency reported with no identity test
- No reviewer sign-off
- Product, strength or lot that doesn’t match your label
Get help reading your results
Our Houston lab runs HPLC and LC-MS testing for compounding pharmacies, businesses and consumers, and we’ll walk you through any report we issue. See our HPLC testing lab, compounding pharmacy potency testing, testing for individuals, how accurate HPLC is and full lab testing services, including endotoxin (LAL), microbiology, ICP-MS, TOC and extractables/leachables. To request testing, call 936-379-5515 or email info@renewlabgroup.com, or use our contact form.
Related questions
What does “conforms” mean on a certificate of analysis?
It means the result met the acceptance criterion in the specification. For an HPLC identity test, it usually means the sample’s main peak matched the reference standard’s retention time under the same conditions.
What is a good HPLC purity percentage?
There is no single number. Acceptable purity depends on the product’s specification, which sets limits for impurities and degradation products (FDA Q6A).
Why doesn’t my certificate of analysis include a chromatogram?
Many COAs show a summary only. Complete test records include the chromatograms behind each result (21 CFR 211.194), so ask the issuing lab for them.
Can Renew Lab Group test my product and explain the report?
Yes. Our Houston lab runs HPLC and LC-MS testing, and we walk you through every report we issue. For a quote, call 936-379-5515 or email info@renewlabgroup.com.
Talk to the lab about reading your HPLC results
Tell us what you need tested and we’ll recommend a method and send a quote. Contact us at 936-379-5515 or info@renewlabgroup.com for current pricing, turnaround and sample requirements. Samples can be dropped off at our lab at 6001 Central Crest, Houston, TX 77092.
Sources
- 21 CFR 211.194: Laboratory records (Cornell LII)
- Waters: How does high performance liquid chromatography (HPLC) work?
- Shimadzu: Principle of separation in HPLC
- FDA: Q3B(R2) Impurities in New Drug Products
- FDA: Q2(R2) Validation of Analytical Procedures
- FDA: Q6A Specifications, test procedures and acceptance criteria
Researcher resources
- Shop Bacteriostatic and Sterile Water
- View Our Certificate of Analysis
- Free Reconstitution Calculator
- Compare BAC Water Products
Keep reading
- What Is a Beyond-Use Date (BUD)?
- Can You Use Tap Water in an Ultrasonic Diffuser?
- What Is ICP-MS Testing?
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