{"id":13434,"date":"2026-09-17T14:49:46","date_gmt":"2026-09-17T14:49:46","guid":{"rendered":"https:\/\/maionais.com\/blog\/how-to-read-cbd-coa\/"},"modified":"2026-09-17T14:49:46","modified_gmt":"2026-09-17T14:49:46","slug":"how-to-read-cbd-coa","status":"publish","type":"post","link":"https:\/\/maionais.com\/en\/blog\/how-to-read-cbd-coa\/","title":{"rendered":"How to read a CBD certificate of analysis (COA) step by step"},"content":{"rendered":"

When someone buys quality CBD flowers, oils or extracts, the product usually comes with a certificate of analysis, or COA. It is a technical document that sets out the results of the chemical analysis of the product carried out by an independent laboratory. Knowing how to read it is the most valuable tool for checking what you are buying. This article explains what a COA contains, what key information to look for and which warning signs should set off alarm bells.<\/p>\n

What a COA is and who issues it<\/h2>\n

A COA is a laboratory report that certifies the chemical composition of a specific batch of product. It is issued by an accredited laboratory, ideally independent of the manufacturer or grower, although in practice this is not always the case. The best COAs are those issued by laboratories with ISO 17025 accreditation, the international standard for testing and calibration laboratories.<\/p>\n

A COA is not a generic brand document: it must be specific to the batch tested. Each production batch can have a slightly different composition, so the COA should correspond exactly to the product being purchased, with a matching batch number.<\/p>\n

Cannabinoids: the first thing to read<\/h2>\n

The first block of relevant information in any COA is the cannabinoid profile. In a CBD product, the compounds that usually appear are:<\/p>\n

CBD (Cannabidiol):<\/strong> The main cannabinoid. It is expressed as a percentage of dry weight. In flowers, typical values on the market range from 8% to 25%. In CBD oils<\/a>, from 5% to 30% depending on the concentration of the formulation.<\/p>\n

CBDA (Cannabidiolic acid):<\/strong> The acidic precursor of CBD, present in the plant before decarboxylation. In unprocessed flowers, CBDA is often the most abundant compound. Many laboratories give a “total CBD” value by adding CBD + (CBDA \u00d7 0.877), which is the molecular conversion that would occur on decarboxylation.<\/p>\n

THC (Delta-9-tetrahydrocannabinol):<\/strong> The most important value from a legal point of view. It must be below 0.2% (0.3% under some regulations). If the COA shows THC above this threshold, the product does not comply with Spanish and European regulations.<\/p>\n

THCA:<\/strong> The acidic precursor of THC. As with CBDA, some regulators calculate “total THC” as THC + (THCA \u00d7 0.877) to determine the psychoactive potential of the product.<\/p>\n

Other cannabinoids that may appear and are currently being researched are CBG (cannabigerol), CBC (cannabichromene), CBN (cannabinol, which indicates some oxidation of THC) and CBDV.<\/p>\n

Contaminants: the most important part for safety<\/h2>\n

A complete COA includes contaminant testing, which is the most relevant part for determining whether a product is safe to use. The contaminants usually tested for are:<\/p>\n

Heavy metals:<\/strong> Cannabis is a hyperaccumulator plant, which means it absorbs the metals present in the soil very efficiently. Testing for heavy metals (lead, cadmium, arsenic, mercury) is essential to confirm that the growing soil was clean. Values must be below the thresholds set by the European pharmacopoeias.<\/p>\n

Pesticides:<\/strong> Pesticide residues (insecticides, fungicides, herbicides) can remain in the final product. A good COA includes a pesticide panel (often between 50 and 200 compounds) with the result for each one below the limit of detection.<\/p>\n

Mycotoxins:<\/strong> Toxins produced by moulds such as aspergillus or penicillium, which can appear in products that have been poorly stored or exposed to excessive humidity. Their presence is a serious warning sign.<\/p>\n

Residual solvents:<\/strong> Especially relevant for extracts and resins, where the extraction process can leave traces of solvents such as ethanol, butane or hexane. Values should be minimal or not detected.<\/p>\n

Microbiology: the part that is often left out<\/h2>\n

Microbiological testing is the least common in COAs on the CBD market, but the most important for confirming the absence of pathogens. It includes total counts of aerobic bacteria, coliforms, E. coli, salmonella and moulds. Its absence from a COA does not necessarily mean the product is contaminated, but a COA that includes microbiology is a sign of greater analytical rigour.<\/p>\n

Terpenes: the aromatic signature of the product<\/h2>\n

More and more COAs include terpene analysis, which identifies and quantifies the compounds responsible for the aroma. This analysis is not mandatory but is very useful for verifying the product’s declared aromatic profile and for users looking for strains with specific terpene profiles.<\/p>\n

Terpene analysis is usually carried out by gas chromatography (GC-MS) and shows the terpenes identified as a percentage of the product’s weight. The most common terpenes in cannabis (myrcene, limonene, beta-caryophyllene, linalool, pinene, humulene) have different olfactory detection thresholds and very different aromas.<\/p>\n

Red flags on a COA<\/h2>\n

Several situations should make you doubt the validity of a COA. The most obvious is when the batch number on the COA does not match that of the product you have bought: you may be looking at an analysis of an earlier or different batch.<\/p>\n

Another problematic sign is a COA issued by the manufacturer itself rather than by an external laboratory. In-house testing can be useful for quality control during production, but it is no substitute for external verification.<\/p>\n

A missing contaminant analysis (only a cannabinoid profile, with no metals, pesticides or microbiology) makes for an incomplete COA that does not allow you to assess the safety of the product, only its cannabinoid composition.<\/p>\n

Finally, results that are “too perfect” (CBD exactly at the level stated on the label, with no variation at all) can be a sign of a forged document. Real analyses show values with decimals and slight variations from what is declared, because the chemical composition of plants is not exactly uniform from batch to batch.<\/p>\n

Sources and scientific references<\/h2>\n
    \n
  • ISO\/IEC 17025:2017. “General requirements for the competence of testing and calibration laboratories.” International Organization for Standardization.<\/li>\n
  • European Pharmacopoeia (Ph. Eur.). “Cannabis flower monograph.” EDQM, Strasbourg.<\/li>\n
  • Hazekamp, A. (2018). “The Trouble with CBD Oil.” Medical Cannabis and Cannabinoids<\/em>, 1(1), 65\u201372.<\/li>\n
  • AESAN (2021). “Information note on cannabidiol (CBD) as a novel food.” Spanish Agency for Food Safety and Nutrition.<\/li>\n<\/ul>\n
    \n

    Products from maionais.com are intended for topical or decorative use and have no psychoactive effects. They are not medicines and do not replace medical treatment. References to studies published on this website do not constitute official medical claims; consult a healthcare professional if you have any doubts. All products have THC test results < 0.2 % in accordance with Spanish Royal Decree 1729\/1999 and Czech Act No. 167\/1998. Use of this website for unlawful purposes is strictly prohibited. Greenfield Distribution s.r.o. \u00b7 CZ21848858 \u00b7 H\u0159ebenk\u00e1ch 815\/130, 150 00 Prague.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

    When someone buys quality CBD flowers, oils or extracts, the product usually comes with a certificate of analysis, or COA. […]<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_joinchat":[],"footnotes":""},"categories":[99,103],"tags":[],"class_list":["post-13434","post","type-post","status-publish","format-standard","hentry","category-blog-en-2","category-cannabis-en-2"],"acf":[],"_links":{"self":[{"href":"https:\/\/maionais.com\/en\/wp-json\/wp\/v2\/posts\/13434","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/maionais.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/maionais.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/maionais.com\/en\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/maionais.com\/en\/wp-json\/wp\/v2\/comments?post=13434"}],"version-history":[{"count":0,"href":"https:\/\/maionais.com\/en\/wp-json\/wp\/v2\/posts\/13434\/revisions"}],"wp:attachment":[{"href":"https:\/\/maionais.com\/en\/wp-json\/wp\/v2\/media?parent=13434"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/maionais.com\/en\/wp-json\/wp\/v2\/categories?post=13434"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/maionais.com\/en\/wp-json\/wp\/v2\/tags?post=13434"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}