A certificate of analysis, usually shortened to COA, is the laboratory’s written record of what it found in one sample. Kratom shops of every size link to them, and the pages can look dense the first time. This guide walks through what happens to a sample, what each line on the certificate means, and what to look for on any vendor’s paperwork, ours included.
What a testing laboratory does with a sample
Testing begins with a physical sample. Someone, usually the producer or an exporter, packs a small quantity of powder, labels it and sends it to an independent laboratory. The lab logs the date the sample arrives, assigns it an internal number, and runs a set of procedures. When the work is done it issues a signed or stamped report with its own report number and date.
Two points follow from that. First, the certificate describes the sample that was sent, not every bag that was ever made from the same plant material. Second, the lab only reports on the parameters that were requested, which is why the “tested for” line near the top of the page is worth reading before you look at any numbers.
The header block, top to bottom
The upper part of the document identifies the lab, its accreditation number, the report number and the issue date. Below that come the date the sample was received and the window during which analysis took place, followed by a description such as form, packing and quantity. Client and reference details sit here too, which is why shops often mask them before publishing a copy.
Check that the sample type matches the product category being discussed, that the dates are plausible in order (received, then analysed, then reported) and that the form is the same as what is sold, for instance a powder.
Moisture and particle size
Moisture is reported as a percentage of the sample’s weight. The lab dries a weighed portion at a set temperature, weighs it again and calculates how much was lost. A limit is printed beside the result; a figure under that limit passes. Moisture matters to a buyer because very damp plant powder is harder to store and is more likely to grow mould.
Mesh, sometimes written as “passing mesh”, is a sieve test. The report states a size, for example 600 micron, and records whether the powder passed through a screen with openings of that size. The result is a pass or fail rather than a number, and the method is gravimetry, which means weighing what stays on the screen.
The mitragynine percentage
Mitragynine is the alkaloid that labs most commonly measure in this plant. On the certificate it appears as a percentage by weight, and the method is generally HPLC, high-performance liquid chromatography. In that technique a prepared extract of the sample is pushed through a column, the compounds separate, and a detector compares each peak with a reference standard to work out the amount.
Some certificates print a minimum next to the figure, such as “≥ 1.2”. That is a specification, and the result either meets it or does not. Because the figure comes from one sample, two lots of the same strain can show different percentages. Looking at several dated reports, as on our lab reports page, gives a better sense of the spread than a single number.
Metals, units and the “<” sign
Lead, cadmium, arsenic and mercury are the four elements most reports cover. Results are given in milligrams per kilogram, written mg/kg, which is the same as parts per million. Each has a ceiling printed next to it.
When you see a result like “< 0.03”, the lab is saying the amount was below the smallest value its method can report reliably. This is called the limit of detection or reporting limit. It is not the same as zero, and it is not a missing figure; it is the honest way to report a result that is too low to measure. Where a number appears without the sign, for example 0.1690, the instrument measured something above the reporting limit, and the question to ask is how that number compares with the ceiling shown beside it.
Two instrument families do most of the work here. ICP, inductively coupled plasma, turns the sample into an ionised gas and measures the elements by the light or mass they produce. AAS, atomic absorption spectroscopy, shines light of a specific wavelength through an atomised sample and measures how much is absorbed. The certificate names the one used for each row.
Microbiology lines
Microbiology is reported differently from chemistry. For E. coli the report gives a count per gram together with a ceiling. A footnote may say the figure comes from a most-probable-number table, which is a statistical method for estimating counts from tubes that show growth. Salmonella is a presence-or-absence check on a stated portion, commonly 25 g, so the result reads “negative” rather than carrying a number.
The method column normally cites a pharmacopoeia chapter or another published standard.
Result versus limit
Every row on a good certificate has three parts: what was found, what the acceptable limit is, and how it was measured. Read them as a set. A result that sits below a “max” limit passes, and a result that sits above a “min” value passes. Sorting these two directions out is the most common stumbling block. Moisture, metals and E. coli have ceilings; mitragynine, where a figure is printed, has a floor.
Also keep in mind who set the limit. The column heading tells you which specification the lab compared against. If a certificate has no limits at all, you can see numbers but you cannot tell whether they were acceptable.
Why the dates and the report number matter
Report numbers are unique to the issuing laboratory, so a number lets a third party ask the lab whether a document is genuine. The dates tell you how old the information is. A report issued eight months ago describes a lot that may be long gone.
The gap between the received date and the report date is useful too. A sample received in May and reported in August would be a reason to ask why. Dates that run backwards are a red flag on any document.
A checklist for any vendor’s report
- Is the testing laboratory named, with an accreditation or licence number you can look up?
- Does the document carry a report number and issue date?
- Do the received and analysis dates make sense in sequence?
- Does every row show a unit, a limit and a method?
- Is the sample type and form the same as the product being sold?
- Is it a PDF of the original rather than a retyped table or a screenshot of a badge?
- Does the vendor say which lot or product the report relates to, and how recent it is?
If a shop only shows a logo that says “tested” without a document behind it, there is nothing to check.
See the certificates we publish
We have gathered the certificates for six strains on one page, each with its own results table and a downloadable PDF: Lab Reports by Strain. Client details and the sample-type wording are masked on our copies, while results, limits, methods and dates are left as the laboratory printed them. To go straight to a product, browse the green, white, red or yellow and gold collections, or the variety packs.