A tungmetallcertifikat (COA) is a batch-specific lab report that documents a product's measured heavy-metal levels, so check the batch or lot number and the laboratory's ISO 17025 accreditation first. If both are in order and the reported values sit below the legal maximums, the document materially supports the product's safety. If either is missing, treat the claim as marketing rather than evidence.
TL;DR:
- Match the lot number on your package exactly to the COA; a generic or reused report cannot verify the product you bought.
- Choose a lab with verifiable ISO 17025 accreditation covering the test, and confirm ICP MS or an equivalent method and a quantification limit below the legal maximum.
- Check that lead, cadmium, mercury, and inorganic arsenic appear separately, with units and individual detection limits; arsenic should be identified in its inorganic form.
- Compare each measured value with the maximum for that supplement’s category; a pass label alone or missing paperwork does not establish compliance.
- If a seller cannot provide a matching report or accreditation details, request them in writing and postpone prolonged use until verification.
Table of Contents
- What a Certificate of Analysis actually is
- Which heavy metals are tested and why cumulative exposure matters
- How laboratories test heavy metals and the standards that make COAs authoritative
- How to read a heavy-metal COA step by step
- Regulatory context: maximum levels and sampling rules that matter to consumers
- Practical consumer checklist: red flags and trust signals when assessing a COA
- How disciplined supplement brands handle COAs
- Treat the COA as procurement due diligence
- FAQ
- Sources
What a Certificate of Analysis actually is
A COA is a laboratory's written statement about one specific production batch. It is not a brand's general assurance and not a seal of approval. Its value comes from being tied to a single lot, so that the numbers on the page describe the capsules, powder or spray sitting in your hand. A quality COA lists the laboratory's accreditation, the testing method and the detection limits, so you can compare the results with legal thresholds in a meaningful way, as the EU sampling and analysis regulation framework implies.
Traceability is what makes the document defensible. When a batch number links the finished product to its raw materials, the lab sample and the report, a problem can be isolated and a recall can be scoped properly. Without that link, nobody can show which units the results describe. Our own raw material traceability guide covers the record-keeping behind this in more detail.
Many documents circulate that look like COAs but fall short. Watch for these patterns:
- A generic "lab tested" statement with no batch or lot number.
- A pass or fail stamp with no measured values.
- A report that names no testing method and shows no detection limit.
- A laboratory name you cannot independently identify.
- A single document reused across many production runs.
None of these proves a product is unsafe. They simply mean the document cannot carry the weight of the claim it is attached to. The Swedish Food Agency makes a related point: distributors are responsible for supplement safety, and documentation such as batch testing for heavy metals belongs in a brand's quality control rather than only in its marketing copy.
For a disciplined buyer, the practical standard is simple. A COA earns trust through specificity: one lot, one method, one identifiable laboratory, measured values with units. Everything vague should be questioned, and everything specific can be verified.
Which heavy metals are tested and why cumulative exposure matters
A standard heavy-metal panel covers four elements: lead (Pb), cadmium (Cd), mercury (Hg) and inorganic arsenic (As). Some COAs add tin or nickel, depending on the product type and the buyer's specification. These metals can accumulate in plant-based ingredients through soil, water and growing conditions, which is why botanical raw materials receive particular attention.
What to expect on a well-built panel:
- Lead, cadmium, mercury and arsenic reported individually, never as one combined figure.
- Arsenic reported as inorganic arsenic where the legal limit is set for that form.
- Each result stated with its unit and the lab's limit of quantification.
- Any additional elements clearly labeled as supplementary to the core four.
The reason this matters more for supplements than for a single meal is repetition. A product taken daily for months delivers its contaminant load again and again. The Swedish Food Agency states plainly that repeated supplement consumption increases cumulative exposure risk, and it advises caution with products from sources that have a history of lax oversight.
Swedish Food Agency: Supplements are often consumed in repeated doses over long periods, which raises the risk of accumulated exposure if contaminants are present.
Read a COA with that in mind. A result that looks small in a single sample is not the whole picture when the product becomes part of a daily routine. This is why the batch link matters so much: you want evidence that every lot you buy over time was tested, not one favorable report from a single early production run.
The same agency notes that investigations have found some supplements, notably certain traditional medicine products, contaminated with arsenic, lead or mercury. That is a reason for consistent verification, not a reason for alarm about every product. The point is that testing evidence should be routine, repeatable and inspectable, in the same way you would expect it from any supplier in a demanding procurement process.
How laboratories test heavy metals and the standards that make COAs authoritative
Authority in a COA comes from three things working together: an accredited laboratory, a sensitive method and a sampling approach that makes the sample representative of the batch.
Accreditation. ISO 17025 is the international standard for testing laboratories. Accreditation confirms that a lab has demonstrated technical competence, controls its quality processes and can trace its measurements. Authoritative results typically come from ISO 17025-accredited laboratories using sensitive techniques such as ICP-MS. Ideally the accreditation scope covers the specific analysis performed, not just the lab in general.
Method. ICP-MS, inductively coupled plasma mass spectrometry, is the sensitive technique usually used for trace metals. It can detect very small concentrations, which matters because legal limits for contaminants are set low.
Sampling. A perfect measurement of an unrepresentative sample proves little. Sampling and analysis should follow established methods, for example Commission Regulation (EC) No 333/2007 in its consolidated form, which sets performance and sampling requirements for lead, cadmium, mercury and arsenic control. The same Maltese authority page notes that Regulation 2021/705 specifically addresses sampling for food supplements, spices and algae to keep testing representative.
Detection limits. The limit of quantification (LOQ) tells you the lowest level the lab can reliably measure. This is the most overlooked line on a COA. If a report says "not detected" but the LOQ is higher than the legal maximum, the result says nothing useful about compliance. A low LOQ relative to the limit is what turns "not detected" into real reassurance.
Elements to look for in the method statement:
- The named technique, such as ICP-MS or an equivalent validated method.
- The sample preparation approach, such as acid digestion.
- The LOQ for each metal, with units.
- A reference to the sampling approach or regulation followed.
Pro Tip: Compare each LOQ with the legal maximum for that metal. A COA is only informative where the lab can measure well below the limit.
How to read a heavy-metal COA step by step
Work through the document in order. Each step is quick, and together they separate a real report from decoration. Our COA check follows the same logic in a shorter format for repeat use.
- Match the batch. Confirm the batch or lot number on the COA is identical to the one printed on your product's packaging. A close match is not a match.
- Verify the laboratory. Find the lab's name and its ISO 17025 accreditation. Where possible, check the accreditation scope with the accrediting body to see that heavy-metal analysis in your product type is covered.
- Confirm method and LOQ. Look for ICP-MS or an equivalent validated method, and read the reported limit of quantification for each metal.
- Read the values and units. Results are usually shown in mg/kg or µg/kg. Check that the unit is stated and that the result is compared with the acceptance or regulatory limit, not just labeled "pass".
- Check traceability. Look for the sample date, analysis date, instrument or analyst identification, and any sampling plan or chain-of-custody reference.
If a step cannot be completed because the information is absent, note that gap. Absence of data is itself a finding. For recurring purchases, keep each COA with the matching purchase record, so you can compare batches over time and spot any change in the lab, the method or the reported levels.
Regulatory context: maximum levels and sampling rules that matter to consumers
The legal baseline in the European market comes from EU Regulation 2023/915, which sets maximum levels for specific contaminants, including lead, cadmium, mercury and inorganic arsenic, that apply to food supplements sold on the European market. Products above these maxima are prohibited from being placed on the market. The regulation covers processed, dried and compound foods, so thresholds are tied to the edible part of the product.
The EUR-Lex summary of the regulation adds that maximum levels apply to edible parts and compound foods such as supplements, with processing taken into account. In practice, this means the limit that applies to a given product depends on its category, so a COA should state which limit it is measured against.
What this means for you when reading a report:
- A COA should reference the applicable maximum level, not only list raw numbers.
- Results above the relevant maximum mean the product cannot lawfully be sold.
- Sampling and analysis for official control must follow the annex methods set out in the sampling regulations, which define sample handling and laboratory performance.
- National control programs, such as those run by the Swedish Food Agency, require accredited laboratories meeting performance criteria, and results are assessed against the limits in Regulation (EU) 2023/915.
A COA that cites the relevant regulation, or uses legally referenced methods, strengthens confidence because it shows the lab tested against the standard an inspector would apply. It does not replace official control, and it does not turn a voluntary report into a legal guarantee. It does show that the brand is operating with the same yardstick as the authorities, which is the right expectation for any supplier whose products you take daily.
Practical consumer checklist: red flags and trust signals when assessing a COA
Use this as a quick screen before you commit to a product or a reorder.
Trust signals to expect:
- An ISO 17025-accredited laboratory with a verifiable identity.
- A batch number that matches your packaging.
- A named method such as ICP-MS.
- LOQ reported for each metal, with units.
- A full panel covering lead, cadmium, mercury and arsenic.
- An analysis date and traceability details such as chain of custody.
Red flags:
- Only a pass or fail stamp, with no values.
- No batch linkage, or one document covering every batch.
- No stated method and no LOQ.
- A laboratory you cannot identify or verify.
- Values with missing or ambiguous units.
- Reluctance to provide documentation when asked.
If information is missing, take the same steps you would in any supplier review. Request the batch-specific COA in writing. Ask for evidence of the lab's accreditation and its scope. Hold off on prolonged use until the documents are verified. A brand that handles evidence well will answer these requests quickly and without friction. Slow, vague or defensive responses tell you something useful about how the rest of the quality system operates. Our executive COA protocol lays out a routine for building this habit, and our guide on how to identify a sophisticated supplement brand describes what documentation to expect from a serious supplier.
Pro Tip: Save every COA next to the order confirmation. A folder of batch reports turns a one-off check into a record you can compare across years.
How disciplined supplement brands handle COAs
Good practice is easy to describe, and easy to demand. A disciplined brand supplies batch-linked COAs on request, uses ISO 17025-accredited laboratories, and includes method statements and LOQs so the numbers can be interpreted. High-agency buyers tend to favor suppliers that make batch-specific COAs inspectable, and a company that cannot clearly link products to batch lab results fails the transparency standard careful buyers apply.
Behind the document sits the discipline that makes it credible: chain of custody from production to laboratory, change control when suppliers or methods shift, and archived records that let a past batch be reconstructed years later. That is what separates a report that can be defended from one that merely exists.
We produce in small batches in Sweden. We use the same five-step logic described above as our own template for verification, and we encourage members to apply it to us as rigorously as to anyone else. If you want a repeatable routine, our COA check for executives and the protocol are built for exactly that purpose.
Treat the COA as procurement due diligence
I treat a COA the way I would treat a contract clause: a document to be read, filed and checked against the product, not a decoration on a sales page. The men we write for already run their businesses on records, verification and accountability. Applying a few minutes of the same discipline to something you take every day is a modest investment with an outsized return in confidence.
My advice is plain. Keep the COA for every recurring purchase. Insist on accredited testing and a clearly stated method. Notice when a supplier makes verification easy, and when it makes it hard, because that difference usually reflects the whole operation. If you want a routine you can repeat without thinking, our deeper checklists are written for that, and you can find them across our journal and protocol articles.
Vigilance of this kind is not suspicion. It is respect for your own long-term performance.
— Joakim
This article is general information, not a substitute for advice from a qualified doctor. Consult a qualified healthcare professional about your own circumstances before acting on anything here.
FAQ
How can I check that a COA matches my product?
Compare the batch or lot number printed on your packaging with the one on the COA. They must be identical. If the report shows no batch number, or covers every lot at once, it cannot describe your specific product.
Which units and abbreviations appear on a heavy-metal COA?
Results are commonly given in mg/kg or µg/kg, with the metals abbreviated as Pb (lead), Cd (cadmium), Hg (mercury) and As (arsenic). LOQ means limit of quantification, the lowest level the lab can reliably measure, and ICP-MS names the analytical method.
Does "not detected" mean a product is free of heavy metals?
Not necessarily. It means the level was below what the method could measure, so the LOQ matters. If the LOQ is low relative to the legal maximum under EU Regulation 2023/915, the result is reassuring; if it is high, the result says little.
Should every batch of a supplement have its own COA?
Yes, because a COA is a lot-specific document. Contaminant levels can vary between batches with raw material source and growing conditions, and supplements are taken repeatedly, so cumulative exposure makes consistent batch testing the sensible standard.