Certificates of Analysis and Basic Testing Concepts

Lesson 6.1 · 11 min

What a certificate of analysis is

Objective: Explain what a certificate of analysis reports and who produced it.

A certificate of analysis, usually called a COA, is a document from a lab reporting the results of tests run on a specific sample. It typically lists things like identity, purity, and sometimes the presence or absence of specific contaminants, along with the method used to test for each.

A COA is tied to a particular sample from a particular batch, tested on a particular date. It is a snapshot, not a permanent guarantee. A vial sitting in a warehouse for a year after that testing was done may no longer match what the COA reported, even if nothing about the paperwork has changed.

Reading a COA carefully means checking that it actually corresponds to the product in front of you, not just to the same product name in general. Batch numbers on the COA and on the container should match. If they don't, the document is not describing what you actually have.

Certificate of analysis:

A lab report describing the results of specific tests run on a sample from a specific batch, at a specific point in time.

Batch:

A specific production run of a material. Different batches of the same product can differ from each other.

Lesson 6.2 · 10 min

What a COA does not prove

Objective: State clearly what a COA does not establish, including sterility, safety, and suitability for any use.

A COA does not prove that the vial you are holding came from the batch it claims to. COAs can be copied, altered, or simply attached to the wrong product, whether by mistake or on purpose. The document alone cannot verify itself.

A COA also does not prove that the material has stayed the same since it was tested. Storage conditions, time, and handling after testing can all change a material, and a COA from the day it was made says nothing about the day you actually use it.

Finally, a COA only reports what it was asked to test for. A report showing high purity by one method says nothing about a contaminant that method was never designed to detect. A COA is only as thorough as the list of tests actually run, and that list is often shorter than people assume.

Lesson 6.3 · 10 min

How purity testing actually works, in simple terms

Objective: Describe in plain terms how identity and purity testing work.

One of the most common tests is called HPLC, which separates the different substances in a sample so they can be measured individually, based on how each one moves through a specialized column. The result is usually reported as a percentage: how much of the total material detected was the substance you were looking for.

Another common test is mass spectrometry, which measures the mass of molecules in a sample to help confirm identity, essentially checking whether the molecule actually weighs what your target molecule should weigh. It's a way of checking not just how pure something is, but whether it's the right thing at all.

Neither test is magic, and neither test checks for everything. Each method is good at detecting certain kinds of problems and blind to others. This is exactly why a thorough COA lists several different tests rather than just one: to cover more of the ways a sample could be wrong.

HPLC:

High performance liquid chromatography, a common lab method that separates the components of a sample so each one can be measured.

Mass spectrometry:

A lab method that measures the mass of molecules in a sample, often used to help confirm a substance's identity.

Lesson 6.4 · 12 min

Reading a COA line by line

Objective: Read a COA field by field and say what each entry means.

Open a certificate of analysis and work through it in order. Who issued it? Is that an independent laboratory with a name and address, or is it unbranded? What product name and lot number does it reference, and does that lot number match the vial in front of you? What was the date of analysis, and how long ago was that relative to the material you received?

Then look at the methods. A serious report names the technique used, such as high performance liquid chromatography for purity or mass spectrometry for identity, and shows the actual data or chromatogram rather than only a number. A single line that says purity greater than 99 percent, with no method and no supporting trace, is a claim rather than a result.

Finally, check what is not there. Many reports cover identity and purity but say nothing about sterility, endotoxins, residual solvents, or heavy metals. Absence of a test is not a passing result. Knowing which questions a report leaves unanswered is the most useful skill in this module.

Lot number:

An identifier tying a specific batch of material to the records and test results for that batch.

Chromatogram:

The graph produced by a separation method such as HPLC, showing peaks that correspond to the components of a sample.

Lesson 6.5 · 10 min

Spotting a questionable report

Objective: Identify red flags that indicate a report may be incomplete, reused, or fabricated.

Fabricated and recycled analytical reports exist in this market. Common warning signs include no laboratory name, no analyst or signature, no method listed, no date, a lot number that does not appear on the product, an image that is a screenshot of a screenshot, and identical reports reused across visibly different products or batches.

Another pattern is a real report used dishonestly. A supplier tests one batch, then attaches that report to every batch sold afterward. The document is genuine, but it says nothing about the vial you received. Matching the lot number is what makes a report meaningful to you.

When a report looks questionable, the right response is to ask the supplier directly for the laboratory name, the method, and a report matching your lot, and to note the answer in your records. How a supplier responds to that question is itself useful information.