How to Read a Certificate of Analysis for DDW | Yavelle

Yavelle 25ppm deuterium-depleted water certificate of analysis from Isotech Laboratories, lab number 1004783, reported 23 March 2026, showing a measured result of delta-D minus 871.7 per mille relative to VSMOW, equal to 20 ppm deuterium

Yavelle Journal · Education · 6 min read

Education Lab Tested ppm Verification FAQ
For deuterium-depleted water, the Certificate of Analysis is the proof. It is the one document that turns "25 ppm" from a claim into a measured fact. The trouble is that a real lab report can look intimidating, full of delta values, per mil symbols and reference standards. This guide walks you through it in plain English, including the simple sum that converts the technical figure into the ppm you actually care about.

Because you cannot see, taste or home-test deuterium, an independent laboratory result is the only way to know a water's true deuterium level. Learning to read that result puts the power back in your hands as a buyer. It is easier than it looks.

What a Certificate of Analysis Actually Is

A Certificate of Analysis, or COA, is simply a report from a laboratory stating what it measured in a sample. For DDW, the headline measurement is the deuterium concentration. Around that core number, a trustworthy certificate carries the details that let you trust it: which lab did the work, which sample or batch it relates to, when it was tested, and by what method.

The Five Things to Look For

On the certificate Why it matters
A named laboratory An identifiable, independent lab stands behind the result
A sample or batch ID Ties the report to the actual product, not a one-off sample
The test date Shows the result is current, not years old
The analysis method Confirms a recognised isotopic technique was used
The measured value The deuterium result itself, usually as a delta value

Delta and Per Mil: The Number That Confuses Everyone

Here is the part that trips people up. Laboratories don't always print the deuterium result directly as ppm. Instead they use delta D (written δD), a value in per mil, which means parts per thousand and uses the symbol ‰. Delta D describes how far the sample sits below or above the international reference, Vienna Standard Mean Ocean Water (VSMOW), which is fixed at 155.76 ppm.

A negative delta means less deuterium than that standard. The bigger the negative number, the more depleted the water. So a strongly negative δD, something like −870‰, is the sign of a deeply depleted water. You just need one small sum to turn it into a figure you recognise.

Turning It Into a ppm You Can Trust

The conversion is a single line:

ppm = 155.76 × (1 + δD ÷ 1000)

Take a worked example. Suppose a certificate reports a δD of −871.7‰. Divide −871.7 by 1000 to get −0.8717, add 1 to get 0.1283, and multiply by 155.76. The answer is about 20 ppm. In other words, that intimidating −871.7‰ is simply a water measured at roughly 20 parts per million of deuterium. Once you know the sum, any deuterium certificate becomes readable.

Why the Certificate Often Reads Lower Than the Label

That worked example is worth pausing on, because the measured 20 ppm sits below the 25 ppm printed on the label, and people sometimes assume a mismatch means something has gone wrong. It is the opposite. The number on a Yavelle bottle is the specification we guarantee, not the best result we have ever recorded. We label 25 ppm and commit to every batch meeting it, so a batch that measures 20 ppm is a batch comfortably inside spec.

This is ordinary practice for a measured food product: you publish the threshold you will always meet, and real production usually lands on the good side of it. So when you read a certificate against a label, the question is not "do these two numbers match exactly?" but "is the measured value at or better than the specification?" A certificate reading lower than the labelled ppm is a certificate doing its job.

Red Flags to Watch For

Just as useful is knowing when to be sceptical. Be cautious of a certificate with no named laboratory, no batch or sample identifier linking it to the product, an old or missing date, no stated method, or simply a bare "25 ppm" claim with no underlying lab value at all. A real report shows its working, and where no report is available there is simply nothing for you to check.

The bottom line A Certificate of Analysis is the proof behind any DDW. Check for a named lab, a batch link, a recent date, the method and a measured value, then convert the delta figure to ppm with ppm = 155.76 × (1 + δD ÷ 1000). Compare the result against the labelled specification rather than expecting an exact match. It turns a technical document into a simple check you can do yourself.

See One for Yourself

You can put this into practice on ours. Yavelle publishes its latest lab result so you can read it exactly as described above; view our Certificate of Analysis here. For more on choosing between brands, our buyer's guide covers what to look for on a certificate.

References

  1. International Atomic Energy Agency (IAEA). (1995). Reference and Intercomparison Materials for Stable Isotopes of Light Elements. IAEA-TECDOC-825. IAEA, Vienna. (Source of the VSMOW value of 155.76 ppm and delta notation.)
  2. Goncharuk, V. V., Kavitskaya, A. A., Romanyukina, I. Y., & Loboda, O. A. (2013). Revealing water's secrets: deuterium depleted water. Chemistry Central Journal, 7(1), 103. https://doi.org/10.1186/1752-153X-7-103 PMC3703265

This article is for educational purposes and explains how to read a deuterium Certificate of Analysis. Reported values vary by sample and testing method and should be treated as approximate.

Yavelle 25ppm Deuterium-Depleted Water is a packaged food. It is not a therapeutic good and is not intended to diagnose, treat, cure or prevent any disease. Information on this page is general and is not medical advice. If you have a health condition or are undergoing treatment, speak with a qualified health practitioner.