Your COA Says “Pass.” Here’s How to Check the Lab Agrees.

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Your COA Says “Pass.” Here’s How to Check the Lab Agrees.

If you buy anything sold with a lab report, from supplements to research compounds, you have probably seen a certificate of analysis, or COA. It is a one-page document with a lab logo, a table of results and a reassuring word in the last column: Pass.

Most guides to reading a COA stop there. They explain what HPLC means, what “purity” measures, and why an endotoxin line matters. That is useful. But it skips the question that matters most: did the lab named on the paper actually issue this paper, for this lot?

A COA is just a PDF. PDFs can be edited, reused across batches, or borrowed from someone else’s test. The good news is that many independent labs now let anyone check a certificate against their own records in a minute or two. Here is how, using a real certificate as the worked example.

Step 1: Find the three identifiers

Every COA worth trusting carries three things that tie it to one specific test:

• The lab’s name and contact details. Not just a logo. Look for a street address, a phone number and a website.
• A laboratory ID or report number. This is the lab’s own reference for the test. It is the most important number on the page.
• A lot or batch number. This is the seller’s reference for the production run that was sampled.

Our example is a certificate for NAD+ 500 mg. It lists Vanguard Laboratory in Olympia, Washington, with a phone number and website. The laboratory ID is V260618-8 008. The lot number is VR03042601500. The report date is July 1, 2026.

If a certificate is missing any of these three, stop there. A COA with no report number cannot be checked by anyone, which means it is asking you to take it on faith.

Step 2: Check the lab is a real, accredited lab

Next, look for an accreditation statement. Testing labs in the US are commonly accredited to the ISO/IEC 17025 standard by bodies such as A2LA. Our example says: “Please consult A2LA Certificate #6377.01.01 for a list of accredited tests.”

That number is checkable too. A2LA keeps a public directory where you can look up a laboratory, confirm its accreditation status and review its published scope of accreditation. Confirm that the lab name and location match the COA, then check whether the specific testing method is included in the accredited scope. A laboratory can be ISO/IEC 17025 accredited without every test it performs necessarily falling within that accredited scope, so the scope should be checked rather than assumed.

Accreditation does not prove a particular result is correct. It tells you the lab is audited against a recognized standard, which is a good start.

Step 3: Go to the lab, not the seller

This is the step most people skip. Do not rely on a “verify” button alone if you cannot see where it goes. Go to the lab’s own website and look for a verification or report-lookup page.

Vanguard runs a public verification site. Entering the report details, or opening the verification link printed for the report, brings up the lab’s own record: https://verifiedbyvanguard.com/verify/413f4c5a-4e9b-4d36-a47f-adac0f2d4350

When you land on a lab’s record, compare it line by line with the PDF you were given:

• Compound: NAD+
• Laboratory ID: V260618-8 008
• Report date: July 1, 2026
• Results: the same numbers, to the same decimal place

In our example the lab’s record is marked authentic and matches all four. Notice what it does not show: the seller’s lot number. Labs record their own report ID, not your supplier’s batch code, so the report number is the anchor. The lot match happens in Step 5, between the certificate and the label on your product.

If any of these differ, the PDF you were handed is not the document the lab issued. That does not always mean fraud. Sometimes a lab reissues a corrected report, which should carry a new date. But it always means you should ask the seller which version is current and why.

If the lab has no verification page, email or call them with the report number and ask them to confirm it. A legitimate lab will tell you whether that number exists and who it was issued to.

Step 4: Read the results with the right questions

Once you know the document is genuine, the numbers are worth reading. Our example reports:

• Chromatographic purity (NAD+) by HPLC: 98.55%
• Chromatographic purity (total): above 99.80%
• A separate line for nicotinamide: 1.45%
• Quantity of NAD+ by HPLC: 616 mg, against a 500 mg label
• Endotoxins by LAL: Pass, under 5.00 EU/mg

Two lessons sit inside those lines.

First, purity and quantity are different questions. Purity tells you what share of the material is the compound you expected. Quantity tells you how much of it is actually in the vial. A high purity result says nothing about whether the vial holds the stated amount, so look for both. In this case the measured quantity came in above the label. That is not necessarily better or worse on its own; the important point is that the quantity was measured and can be compared with the stated amount.

Second, the “total” purity and the compound-specific purity are not the same number. The total figure counts closely related material, such as nicotinamide here, while the compound-specific figure counts only the target. A certificate that shows only the flattering total is telling you less than one that shows both.

Step 5: Read the fine print the lab wrote for you

Near the bottom of most COAs is a paragraph nobody reads. Read it. Ours says the lab “did not observe or participate in the sample selection process, and cannot confirm the authenticity of the sample or its representativeness of the associated lot/batch.”

That is not a red flag. It is the lab being honest about the limits of any COA. The lab tested the sample it was sent. It cannot promise that every vial in the lot matches that sample. This is exactly why matching the lot number on your product label to the lot number printed on a verified certificate (here, VR03042601500) matters. It is the only link between the paper and the thing in your hand.

A quick checklist

Before you trust a COA, you should be able to answer yes to each of these:

1. Does it name a real lab with a street address and phone number?
2. Does it carry a lab report number and a lot number?
3. Is the lab accredited, and do its accredited tests cover the methods on the page?
4. Did you find the same report on the lab’s own website, or get the lab to confirm it?
5. Does the lot number on your product match the lot on the certificate?
6. Does it show both purity and quantity?

Sellers who expect to be checked tend to make this easy. Some publish their certificates in one place, with the lot numbers and the lab’s verification links side by side. You can see one example at https://hellostacks.com/coa. Whoever you buy from, the habit is the same: take the report number to the lab, and let the lab have the last word.

About the author: Johnny works at Hello Stacks, a US-based supplier of research compounds that publishes third-party certificates of analysis. Hello Stacks products are for research use only.