Reading a specification and a certificate of analysis

Updated

A specification is the agreed list of a product's properties and limits: what a delivered lot is tested against. A certificate of analysis (COA) gives the results for one lot. This chapter goes through the lines of a licorice root specification, the ones on our product pages and the ones buyers add, and explains what each figure means and how to compare two of them. It describes the standards, not our test results.

Maximum, minimum and typical

  • "≤" or "not more than" is a maximum: moisture ≤ 12 % means any result up to 12 % passes.
  • "≥" or "not less than" is a minimum: glycyrrhizic acid ≥ 4 % means a result of 4 % or more passes.
  • "Absent" means not found in the amount tested. A good specification says how much: Salmonella absent in 25 g is a different test from absent in 1 g.
  • A typical value is what is usually found. It is information, not a limit, and a lot can differ from it.

Compare limits with limits and results with results. A supplier's minimum of 4 % and another's typical value of 5 % do not say which root is richer.

Glycyrrhizic acid

Glycyrrhizin, the sweet compound of licorice, occurs in the root as salts of 18β-glycyrrhizic acid, and specifications state it as the acid. It is the figure buyers compare first, and two things change it:

  • The method. Methods differ in what they measure. Liquid chromatography (HPLC) separates glycyrrhizic acid from the root's other compounds before measuring it; a spectrophotometric (UV) method measures how much light a prepared solution absorbs. The Russian State Pharmacopoeia, for example, measures glycyrrhizic acid by UV absorbance at 258 nm. Results obtained by different methods are not directly comparable.
  • The basis. A figure can be stated on the dried root or on the root as it is. The European Pharmacopoeia's minimum is 4.0 % of 18β-glycyrrhizic acid "calculated with reference to the dried drug"; the Russian monograph's minimum is 6 % on absolutely dry material. A root at 4.0 % on the dried basis, with 10 % moisture, holds 3.6 % as it is (4.0 × 0.90).

So compare figures obtained by the same method on the same basis, and ask for both with any figure you are offered, ours included. Our root grades are specified at no less than 4 % and the extraction grade at no less than 3.5 %, and every load's laboratory certificate of analysis gives its glycyrrhizic acid. Glycyrrhizic acid tends to follow root diameter and harvest season; if your specification sets a higher minimum, say so in your enquiry, and lots richer in it can be selected. The full comparison of the pharmacopoeias is on our pharmaceutical page.

Moisture and loss on drying

Loss on drying is the weight a sample loses when dried under set conditions: water plus anything else that evaporates. Moisture, or water content, counts water only. A specification should say which of the two it means, and by which method.

Moisture matters twice: you pay for the water in the load, and the drier the root, the less room mould has to grow in storage. Our specifications set moisture at not more than 12 %, and every load's certificate of analysis gives it. The Russian monograph allows up to 14 %.

Total ash and acid-insoluble ash

Total ash is what remains when a sample is burnt: the plant's own minerals plus any soil or sand. Acid-insoluble ash is the part that does not dissolve in dilute hydrochloric acid, mostly sand and silica, so it measures the soil left on the root.

StandardTotal ashAcid-insoluble ash
Russian State Pharmacopoeia, ФС.2.5.0040.15Not more than 8 %Not more than 2.5 %; whole peeled root, not more than 1 %
US 21 CFR 184.1408 (food use)Not more than 9.5 %, anhydrousNot more than 2.5 %, anhydrous

For the European Pharmacopoeia's limits, see monograph 0277 itself. Washing removes soil from the surface, and peeling removes it with the bark, so both lower acid-insoluble ash. Our specifications give ash as "on each load's certificate of analysis": the laboratory measures it for every load. Name the limit your specification sets in your enquiry.

Foreign matter

Foreign matter is anything that is not the specified plant part: stems, leaves, other plants, stones or soil. The Russian monograph allows organic and mineral matter each up to 1 % in unpeeled root and 0.5 % in peeled root. Our specifications set foreign matter at not more than 1 %.

Microbiology

  • Total plate count (also called total aerobic microbial count): the bacteria that grow on a culture plate from one gram, in CFU/g, colony-forming units per gram.
  • Yeast and mould: the same count for fungi.
  • E. coli and Salmonella: specific organisms, usually required to be absent in a stated amount.

Our specifications set total plate count at not more than 100,000 CFU/g and yeast and mould at not more than 1,000 CFU/g, with E. coli and Salmonella absent. The limits that apply to your product depend on its use and its standard, so check them against the standard your quality department works to.

Contaminants

These are the lines buyers most often add to a specification. The figures below are the regulators' limits, not ours.

  • Heavy metals: lead, cadmium, mercury and arsenic. The US food rule for licorice allows heavy metals (as lead) up to 40 ppm and arsenic up to 3 ppm (21 CFR 184.1408).
  • Pesticide residues: in the EU, Regulation (EC) No 396/2005 sets maximum residue levels in food.
  • Ochratoxin A: a toxin made by some moulds. Regulation (EU) 2023/915 sets 20 µg/kg for dried liquorice root, including in herbal infusions, and 80 µg/kg for liquorice extract for use in food (Annex I, entry 1.2.19). More on the food page.
  • Aflatoxins: specifications for plant materials often set limits for aflatoxin B1 and for the total of B1, B2, G1 and G2.

These are not part of our standard certificate of analysis. Name the ones your specification requires in your enquiry, and the laboratory tests the load for them.

Storage and shelf life

Our root keeps for 36 months from the production date when stored at or below 25 °C, in a cool, dry place away from sunlight. A COA may give an expiry date or a retest date: after a retest date, the material can still be used if it is tested again and passes.

Reading a certificate of analysis

The World Health Organization publishes a model COA for quality control laboratories and for trade in starting materials and finished medicines (WHO Technical Report Series No. 1010, Annex 4). Following it, a full COA shows:

  • who issued it: the name and address of the laboratory, the certificate's number, and "page X of Y" on every page;
  • what was tested: the product and its grade, the batch or lot number, the date of manufacture and the expiry or retest date, and the original manufacturer, plus the trader if there is one;
  • the results: for each test, the method (a pharmacopoeia or a technique), the acceptance criterion, the result as a number, and whether it complies. Tests done by a subcontracted laboratory are marked as such;
  • a conclusion: whether the sample is within the specification;
  • who approved it: the name, signature and date. A laboratory accredited to ISO/IEC 17025 refers to its accreditation.

When one arrives, check that its lot number is the one on the invoice, the packing list and the bags (see the checklist before payment); that its limits are your specification's; that it gives numbers, not only "complies"; and who did the testing.

Each of our export loads has a certificate of analysis from a professional laboratory in Uzbekistan, and you can choose the laboratory. It always covers glycyrrhizic acid, ash and moisture; name any other tests your specification requires, such as microbiology, heavy metals or pesticide residues, in your enquiry. We keep a sample of each shipment for one year.

Sources

All read on 24 October 2026.