Certificates of Analysis

A certificate of analysis (COA) is a lab report for one production batch of a compound. It lists the tests run on samples from that batch, the method used for each, and the result. Every report in this library is matched to a product and a batch number, so you can check it against the label on your vial.

HPLC (high-performance liquid chromatography) is the test used to measure purity. A dissolved sample is pushed through a packed column. Different molecules move through it at different speeds, so they leave the column at different times, and a detector records each one as a peak on a chart called a chromatogram.

Purity is the area of the main peak as a percentage of the area of all peaks. A result of 99.2% means 99.2% of the material the detector saw was the target compound. HPLC shows how pure a sample is, but on its own it does not prove which compound it is. That is what mass spectrometry is for.

Mass spectrometry (MS) confirms identity. The instrument turns molecules into charged particles and measures their mass. The lab compares the measured molecular weight with the expected weight for the compound's sequence or formula. A match within the method's tolerance confirms the batch is the compound on the label.

HPLC and MS answer different questions: MS tells you what the compound is, and HPLC tells you how pure it is. A complete COA reports both.

Endotoxins are lipopolysaccharides (LPS), molecules from the outer membrane of Gram-negative bacteria. They can be introduced during manufacturing and handling, and they are a well-known source of interference in cell-culture work: even small amounts can trigger signaling responses in cell models and skew assay readouts.

Endotoxin is usually measured with the LAL (Limulus amebocyte lysate) test and reported in endotoxin units (EU) per milligram or per milliliter. Lower is cleaner. The report shows the measured level and, where one is given, the limit it was tested against.

USP sterility testing follows General Chapter 71 of the United States Pharmacopeia, the standard method for checking a sample for viable microorganisms. Samples are placed in growth media and incubated, typically for 14 days, then inspected for microbial growth.

The result is reported as no growth detected or growth detected. It describes the samples tested from that batch at the time of testing. Not every report includes sterility, so check which tests are listed on the COA for your batch.

Purity is the share of the detected material that is the target compound, measured by HPLC peak area. At 99% purity, the remaining 1% is made up of other detected components, such as closely related sequences left over from synthesis. Purity describes composition. The amount of compound in the vial is measured separately, as net content.

Net content, also called quantification, measures how much of the compound is actually in the vial and compares it with the labeled amount. A vial labeled 10 mg might test at 10.3 mg, for example. It is reported separately from purity because a sample can be very pure and still be under- or over-filled.

A batch (or lot) number identifies one production run. Every vial from that run carries the same number, and the COA for that run carries it too. Some reports also show the testing lab's own sample or task number, which is a different code from the batch number.

Match the batch number on your vial label to the report to confirm you are looking at the right results. Type it into the chat above to pull up the report.

Third-party testing means the analysis is done by an independent laboratory, not by the supplier. The lab receives samples from the batch, runs its own methods, and issues the report under its own name. Independent results carry more weight than in-house results because the lab has no stake in the outcome.

Start with the basics: the product, batch number and test date on the report should match your vial. Check that the report names the testing laboratory and carries a report or task number. Many independent labs let you look up a report on their own website using that number, which confirms the document has not been edited.

Warning signs include a missing batch number, no lab name, or one report reused across several batches. If anything doesn't line up, contact us with the batch number.

Each batch of a blend such as GLOW or KLOW has one certificate of analysis that covers every component in the vial, so look for each component listed on that single report.

Where we also carry a component on its own, that product has its own batches and its own reports. The chat links them so you can find either one.

Tests are sometimes run separately and issued as separate reports, for example one for purity and identity and another for endotoxin. A batch may also be retested or sent to a second lab. Every report for a batch is listed under its batch number, so you can see all the results together.