Quality Checks for Herbal Raw Materials: What Buyers Test

Quality checks for herbal raw materials answer two questions: is this the right plant and part, and is it clean and safe enough for your use? Buyers usually confirm identity (by appearance, microscopy and chromatography), then check foreign matter, moisture and ash values, and, depending on the end product, microbial counts, heavy metals, pesticide residues and aflatoxins against a pharmacopoeia or their own specification.

This article explains each check in general terms so you can write a sensible specification and read a certificate of analysis with confidence.

Key points

• Identity first: no other result matters if the plant or part is wrong.
• Foreign matter, moisture and ash are simple tests that reveal cleaning, drying and soil contamination.
• Adulteration and substitution are real risks, especially for powders and high-value herbs.
• Microbial, heavy-metal, pesticide and aflatoxin limits depend on the end use and the destination market.
• The Ayurvedic Pharmacopoeia of India (API) and WHO methods are common reference points.

How is the identity of a herb confirmed?

Identity testing compares the material with an authenticated description or reference sample. Typical steps are:

• Macroscopic examination: shape, size, colour, surface, fracture, odour and taste of the whole or cut material.
• Microscopic examination: cell types, crystals, starch grains, fibres and other features. This is especially important for powders.
• Thin-layer chromatography (TLC or HPTLC): a chemical "fingerprint" compared with a reference standard.
• Marker assays by HPLC or other methods, where a specification calls for a minimum content of a known constituent.

DNA-based methods are also used by some laboratories as an additional identity tool, particularly for raw plant material.

What do foreign matter, moisture and ash tell you?

Foreign matter is anything that is not part of the drug as defined: other plant parts, other plants, stones, soil, insects or packing debris. A high figure suggests poor cleaning or careless collection.

Moisture (often measured as loss on drying) shows how well the herb was dried and stored. Excess moisture encourages mould and microbial growth and can make you pay for water rather than herb.

Total ash and acid-insoluble ash measure the mineral residue left after burning. A high acid-insoluble ash usually points to sand or soil. Extractive values (water-soluble and alcohol-soluble) show how much material dissolves in these solvents and can flag exhausted or substandard lots.

Why are adulteration and substitution a concern?

Herbal raw materials pass through many hands between collector and buyer. Common problems include:

• Substitution with a related or similar-looking species, sometimes because a local name refers to more than one plant.
• Wrong plant part, such as stems sold with or instead of roots.
• Exhausted material whose constituents have already been extracted.
• Bulking of powders with cheaper plant material, starch or mineral filler.
• Added colour in some coloured spices and powders.

The defences are simple but must be consistent: specify the botanical name and part, keep reference samples, prefer whole material where you can, and test every lot. Our buyer's guide to sourcing from Kerala explains how to build these steps into the enquiry.

Which safety tests are commonly requested?

The exact limits are set by the pharmacopoeia or regulation that applies to your product and market, but buyers commonly ask about:

• Microbial quality: total aerobic microbial count, yeast and mould count, and absence of specified organisms such as E. coli and Salmonella.
• Heavy metals: typically lead, cadmium, mercury and arsenic.
• Pesticide residues: screened against the maximum residue limits that apply in the destination market.
• Aflatoxins and other mycotoxins, especially for seeds, fruits, roots and spices that may have been stored damp.
• Residual solvents for extracts and oleoresins.

Herbs for food, cosmetics and medicines may have different limits, and the same lot can pass one market's rules and fail another's. State the end use and destination in your specification.

What is the Ayurvedic Pharmacopoeia of India?

The Ayurvedic Pharmacopoeia of India (API) is the official book of quality standards for Ayurvedic drugs in India. It is published by the Pharmacopoeia Commission for Indian Medicine & Homoeopathy (PCIM&H), Ghaziabad, under the Ministry of AYUSH, and has legal status under India's Drugs and Cosmetics Act, 1940. Part I contains monographs on single plant drugs, published across several volumes; a typical monograph gives a description of the drug, identity tests such as microscopy and TLC, and limits for foreign matter, total ash, acid-insoluble ash and extractive values.

Buyers outside India may also refer to other pharmacopoeias used in their markets, and to the World Health Organization's manual Quality control methods for herbal materials (updated edition, 2011), which describes standard test procedures. If your specification names a pharmacopoeia, name the edition and monograph too.

Which documents do buyers commonly ask for?

• Specification sheet describing the product and its limits.
• Certificate of analysis (COA) for the specific lot, stating methods and results.
• Third-party test reports from an accredited laboratory for contaminants. In India, laboratories accredited by NABL are widely used.
• Safety data sheet for oils, extracts and other processed ingredients where relevant.
• Declarations on origin, wild or cultivated status, irradiation, allergens or GMO status, as your market requires.
• Certificates for specific claims, such as organic, only when the supplier actually holds them. Check any certificate with the issuing body.

Export shipping documents, such as the phytosanitary certificate, are covered in our overview of exporting herbal raw materials from India.

How can buyers organise testing sensibly?

A practical approach is to approve a supplier with full testing on the first lots, then test every incoming lot for identity, moisture and a few key parameters, and run the more expensive contaminant tests at an agreed frequency or for higher-risk materials. Keep retention samples of each lot. If you buy powders, consider sourcing whole or cut forms and grinding under your own control.

Global Ayurveda accepts enquiries for Kerala herbal raw materials. The documents available for a given herb and lot are confirmed per enquiry; tell us your specification on the enquiry page.