Understanding Your Magnesium Glycinate TDS: How a Technical Data Sheet Differs from a COA

The TDS and the COA are the two documents every magnesium buyer relies on — and the two that get confused most often. This guide explains what a Technical Data Sheet contains, how it differs from a certificate of analysis, and how to read the two together so you evaluate a material correctly during qualification.

Key takeaways

• A TDS describes the product’s specifications and typical properties; a COA reports the tested results for one specific batch.

• The TDS is the “what to expect” document; the COA is the “what this batch actually is” document.

• A good TDS covers identity, specification ranges, physical properties, applications, packaging, storage, and shelf life.

• Read them together: the TDS sets the expectations, the COA verifies a batch against them.

TDS vs. COA: two documents, two jobs

Ask for a magnesium glycinate’s documentation and you will typically get two things: a Technical Data Sheet (TDS) and a Certificate of Analysis (COA). They look similar — both list parameters and numbers — which is why buyers so often treat them as interchangeable. They are not. The TDS describes what the product is designed to be; the COA reports what a particular batch tested as. Confusing the two leads to real mistakes, such as accepting a TDS as proof of a batch’s quality when only a COA can do that. We cover the COA side in depth in our guide to reading a magnesium glycinate COA; this guide focuses on the TDS and how the two fit together.

What a Technical Data Sheet is

A TDS is the product’s specification and profile document. It describes the material in general terms: what it is, the specification ranges it is made to, its typical physical properties, its intended applications, and practical handling information. It is written once for the product (updated as needed), not per batch, and it is the document you use to decide whether a material is, in principle, right for your project — before any specific batch is even made.

Think of the TDS as the answer to “what should I expect from this material.” It sets the frame against which every batch is later judged, and it is usually the first document you review when shortlisting a grade.

What a Certificate of Analysis is — and the key difference

A COA, by contrast, is batch-specific: it reports the actual tested results for one production lot — the measured elemental magnesium, the measured free magnesium, the measured heavy metals and microbiology, and so on, each by its method. Where a TDS says “elemental magnesium: 12% (specification),” a COA says “elemental magnesium: 12.01% (this batch, by ICP-OES).” That is the key difference: the TDS gives specification ranges and typical values; the COA gives verified results for a specific batch.[1] We walk through interpreting those batch results, including the elemental figure explained in our guide to what 12% elemental magnesium means, in the COA guide.

What a good magnesium glycinate TDS should contain

A thorough TDS gives you enough to evaluate the material on paper. Expect it to cover the product identity (name, form, and where relevant a CAS reference); the specification ranges for the key parameters, including elemental magnesium and free magnesium; physical properties such as appearance, particle size, and solubility characteristics; the analytical methods used; intended applications and format suitability; packaging; and recommended storage conditions with a stated shelf life or retest period.

Several of those items connect to decisions we cover elsewhere: the elemental specification ties to labeling in our guide to elemental magnesium on your Supplement Facts label; physical properties and applications map to our guides for capsules, beverages, and gummies; and storage and shelf life connect to our article on magnesium glycinate stability and shelf life. A TDS that covers these well is doing its job; gaps in it are worth questioning.

How to read a TDS during qualification

When you review a TDS, read it against your own requirements, defined before you started — the first step in our guide on how to evaluate a new magnesium glycinate supplier. Does the elemental specification match your target and sit sensibly within the roughly 10–14% chelate band, rather than well above it in a way that suggests an oxide blend, as we explain in buffered versus unbuffered magnesium glycinate? Do the physical properties fit your format and process? Are the applications aligned with your product? Are storage and shelf life compatible with your supply plan? The TDS is where those go/no-go questions get their first answer.

Reading the TDS and COA together

The two documents are most powerful read together, in sequence. The TDS tells you what the material is supposed to be and whether that fits your project; the COA then tells you whether a specific batch actually meets those specifications. During qualification, you use the TDS to decide the material is a candidate, and the COA — ideally for the batch you will actually receive — to verify that a given lot delivers on the TDS’s promises. Consistency between the two, batch after batch, is one of the clearest signals of a well-controlled material and supplier.

Red flags in a TDS

A few things in a TDS warrant a closer look: missing parameters (no free magnesium, no heavy-metals reference, no methods named); an elemental magnesium specification well above the chelate ceiling with no explanation; vague physical-property or method information; and no stated storage conditions or shelf life. None is automatically disqualifying, but each is a reason to ask questions before you commit — the same diligence we apply throughout the qualification process.

How MagneINNO’s TDS works

MagneINNO provides technical documentation — a TDS describing specification ranges, physical properties, methods, applications, and handling, alongside batch-specific COAs — for its magnesium glycinate and bisglycinate grades, with elemental magnesium specified per grade (a typical COA result of 12.01% by ICP-OES on the 12% grade), free magnesium control, and the rest of the analytical package described on our science and quality pages. The grades themselves are described on our products page.

Specific specification ranges, methods, and batch values should be confirmed for your material during qualification. The aim of this article is to help your team use the two documents for what each does best — the TDS to set expectations, the COA to verify a batch — so a material is evaluated correctly rather than on the wrong document.

What to do next

Next time you evaluate a magnesium glycinate, use the TDS and COA deliberately: read the TDS against your requirements to decide whether the material is a candidate, then use a batch COA to confirm a specific lot meets those specifications. Keep both on file, and check that batches stay consistent with the TDS over time — that is how the two documents together qualify a material.

Want the TDS and a sample COA for a magnesium grade?

Our team can share the Technical Data Sheet and a representative Certificate of Analysis, with methods and specifications spelled out, so your QA team can evaluate the material properly. Request the TDS and COA from MagneINNO.

Frequently asked questions

What is the difference between a TDS and a COA?

A Technical Data Sheet (TDS) describes the product’s specification ranges and typical properties and is written once for the product. A Certificate of Analysis (COA) reports the actual tested results for one specific batch. The TDS says what to expect; the COA verifies what a particular lot is.

What should a magnesium glycinate TDS include?

Product identity, specification ranges for key parameters (including elemental and free magnesium), physical properties (appearance, particle size, solubility), analytical methods, intended applications, packaging, and recommended storage with a shelf life or retest period.

Can a TDS replace a COA?

No. A TDS describes what the product is designed to be, but only a batch-specific COA verifies that a particular lot actually meets those specifications. You need both: the TDS to evaluate the material, the COA to confirm the batch you receive.

How do I use the TDS and COA together?

Use the TDS to decide whether a material fits your requirements and is a candidate, then use the COA — ideally for the batch you will receive — to verify that lot meets the TDS specifications. Consistency between the two across batches signals a well-controlled material.

Disclaimer

This article is written for B2B audiences and provides general information to support documentation review and supplier qualification. It is not regulatory advice and does not establish the quality or compliance status of any material. Document contents and formats vary by supplier, and specifications, methods, and batch values should be confirmed through your own qualification within the applicable FDA framework.

References

[1] U.S. Food and Drug Administration. Dietary Supplements (cGMP, 21 CFR Part 111; identity, purity, strength, composition). https://www.fda.gov/food/dietary-supplements

[2] NIH Office of Dietary Supplements. Magnesium — Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/

[3] U.S. Food and Drug Administration. Daily Value on the Nutrition and Supplement Facts Labels. https://www.fda.gov/food/nutrition-facts-label/daily-value-nutrition-and-supplement-facts-labels

MagneINNO. Published product information, specifications, and analytical methods. https://www.magneinno.com/