Your Guide to Lab-Tested Herbal Quality

Every bag of herbs we ship carries a QR code that links directly to a certificate of analysis (COA). This document proves that what you ordered matches what arrived: verified, tested, and safe. Yet many people scan the code, see rows of numbers and abbreviations, and move on without understanding what they're looking at.

We believe transparency isn't just about providing lab results. It's about helping you read them. A COA is your window into quality control, safety standards, and third-party verification. When you understand what CFU/G means, why heavy metal limits matter, and how microbial testing protects you, you become a more informed herbalist and a smarter consumer.

This guide walks you through each section of a certificate of analysis using our peppermint leaf (LOT # PPRL5202) as a real example. You'll learn what every test measures, what the numbers mean, and which red flags to watch for when evaluating any herbal product.

What Is a Certificate of Analysis?

A certificate of analysis is a document issued by an accredited laboratory that verifies the identity, purity, and safety of a specific batch of material. In the botanical industry, COAs serve as third-party proof that herbs meet established safety standards for microbial contamination, heavy metals, pesticides, and physical purity.

Every lot of herbs we receive undergoes independent testing before it reaches our facility. The COA you access via QR code corresponds to the exact lot number printed on your bag. This batch-specific testing matters because growing conditions, harvest timing, and processing methods vary between lots, even for the same plant species.

What a COA Tells You:

• The botanical identity and lot number of the tested material
• Physical characteristics like color, aroma, form, and particle size
• Microbial load including bacteria, yeast, mold, and pathogens
• Heavy metal concentrations for arsenic, cadmium, lead, and mercury
• Foreign material inspection results (visual and metal detection)
• Certification status such as kosher, wildcrafted, or sterilization method

The American Herbal Products Association (AHPA) publishes widely-accepted microbial and heavy metal limits for botanical ingredients.¹ Most reputable labs reference AHPA standards when determining pass/fail thresholds. Our testing follows AOAC International methods, which are recognized globally for food and botanical analysis.

Material Information: Identity and Traceability

The top section of any COA establishes what you're looking at. Our peppermint COA lists the material name as "Peppermint leaf" with the Latin binomial Mentha piperita. Latin names eliminate confusion. Common names vary by region, but Mentha piperita identifies one specific species recognized worldwide.

The lot number (PPRL5202 in this example) functions as the batch's unique identifier. When you scan the QR code on your bag, the lot number printed on the label must match the lot number on the COA. This matching process ensures you're viewing results for the exact material you purchased, not generic test results from a different batch.

Key Material Details:

• Part: Which portion of the plant was tested (leaf, root, flower, etc.)
• Form: Processing method such as cut and sift, powder, or whole
• Sterilization Method: How microbial load was reduced (steam, irradiation, etc.)
• Manufacture Date: When the lot was processed and packaged
• Retest Date: Shelf life expiration based on stability testing

Our peppermint was steam treated, which uses pressurized steam to reduce microbial counts without chemical residues or irradiation. The manufacture date of February 6, 2025, paired with a three-year shelf life, means this lot should be retested by February 6, 2028. Proper storage in cool, dry conditions extends shelf life and preserves volatile oils.

Physical Characteristics: Sensory Verification

Before any lab instrument touches the sample, trained technicians perform sensory evaluation. This section documents what the herb looks like, smells like, and tastes like. For peppermint leaf, the COA notes green to dark green color, minty and sweet aroma, and minty and fresh taste.

These observations might seem subjective, but they catch problems machines miss. Off colors suggest oxidation or improper storage. Musty odors indicate mold growth. Bitter or chemical tastes reveal contamination. Sensory evaluation also confirms species identity since many herbs have characteristic appearances and aromas that experienced botanists recognize immediately.

The form listed as "cut and sift" tells you the particle size. Cut and sift means the leaves were chopped and sifted through screens to remove stems and achieve uniform sizing. This matters for extraction efficiency and tea brewing. Powdered herbs extract faster but lose volatile oils more quickly during storage. Whole leaves preserve aromatics longer but require more processing before use.

Microbial Testing: Understanding Colony Counts

This section often confuses first-time COA readers because the numbers seem enormous. Our peppermint shows a total plate count of 130,000 CFU/G against a limit of 10,000,000 CFU/G. That sounds like a lot of bacteria. It is, but context matters.

CFU/G stands for colony-forming units per gram. It measures how many viable microorganisms are present in a sample. One CFU represents a single bacterial cell or spore capable of reproducing into a visible colony on a petri dish. The testing method (Petrifilm AOAC 990.12) uses standardized growth media to culture and count these colonies.

Plants grow in soil, which teems with microbes. Even after washing and drying, some environmental bacteria remain on botanical materials. The question isn't whether bacteria exist but whether harmful pathogens are present and whether total counts exceed safe thresholds. Research on herbal safety suggests that total aerobic counts below 10 million CFU/G pose minimal risk.²

What Each Microbial Test Measures:

• Total Plate Count: All aerobic bacteria present (both harmless and potentially harmful)
• Yeast: Fungal organisms that can spoil herbs in humid conditions
• Mold: Filamentous fungi that produce visible growth and potential mycotoxins
• Total Coliform: Indicator bacteria suggesting fecal contamination or poor sanitation
• E. coli: Specific pathogen indicating direct fecal contamination
• Salmonella: Disease-causing bacteria tested using PCR for rapid detection

Our peppermint passed all microbial tests with flying colors. Yeast and mold came back below 10 CFU/G, which is the detection limit. That means the lab found virtually no fungal growth whatsoever. Total coliform measured 200 CFU/G against a limit of 1,000 CFU/G — imagine being allowed to have up to five cookies but only eating one. Both E. coli and Salmonella tested completely negative, confirming zero pathogenic bacteria were detected in the sample.

Steam treatment, which this lot underwent, reduces microbial load significantly while preserving phytochemical content. The absence of pathogens and exceptionally low total counts indicate proper post-harvest handling, effective sterilization, and appropriate storage conditions throughout the supply chain. In practical terms, this peppermint is as clean as herbs get.

Heavy Metal Testing: Safety Limits Explained

Plants absorb minerals from soil, including heavy metals. Some metals like iron and zinc are essential nutrients. Others like lead and mercury are toxic even at low concentrations. Heavy metal testing verifies that contamination stays below established safety limits.

The COA lists four priority metals: arsenic, cadmium, lead, and mercury. These metals accumulate in body tissues over time and can cause serious health problems with chronic exposure. California's Proposition 65 and international pharmacopeias set maximum daily intake limits for these contaminants in herbal products.³

Our Peppermint Heavy Metal Results (Lot PPRL5202):

• Arsenic: 0.07 PPM (limit: 1 PPM) — Pass
• Cadmium: Not Detected (limit: 1 PPM) — Pass
• Lead: 0.11 PPM (limit: 3 PPM) — Pass
• Mercury: 0.02 PPM (limit: 1 PPM) — Pass

PPM stands for "parts per million," a scientific way of expressing trace concentrations. One PPM equals one milligram per kilogram, so 0.07 PPM arsenic means just seven hundredths of one milligram in an entire kilogram of peppermint. That's roughly equivalent to one grain of sand dissolved in fifteen gallons of water.

At typical serving sizes of 1–2 grams per cup of tea, you'd be consuming only 0.00007 to 0.00014 milligrams of arsenic per serving, far less than what's naturally present in many fruits, vegetables, and even bottled waters. In other words, our peppermint's trace reading is nearly immeasurable by ordinary standards and falls thousands of times below any established safety threshold.

The testing method (#C55 AOAC 2015.01) uses inductively coupled plasma mass spectrometry (ICP-MS), which can detect metals at extremely low concentrations. This sensitivity allows labs to catch contamination long before it reaches harmful levels.

Why Heavy Metal Limits Vary: Different regulatory bodies set different thresholds. AHPA recommends limits based on daily consumption patterns. WHO guidelines consider cumulative exposure from all dietary sources. More restrictive limits (like California Prop 65) aim to minimize any measurable risk over a lifetime of exposure. Labs typically test to the strictest standard applicable to their market.

All four metals in our peppermint tested well below their respective limits. Cadmium wasn't detected at all, meaning concentrations fell below the instrument's detection threshold — essentially zero. Lead came in at 0.11 PPM against a 3 PPM limit, and mercury registered 0.02 PPM against a 1 PPM limit. These results confirm that the growing conditions and soil quality produced an exceptionally clean crop without significant heavy metal accumulation.

This section often confuses first-time COA readers because the numbers seem enormous. Our peppermint shows a total plate count of 130,000 CFU/G against a limit of 10,000,000 CFU/G. That sounds like a lot of bacteria. It is. But context matters.

CFU/G stands for colony-forming units per gram. It measures how many viable microorganisms are present in a sample. One CFU represents a single bacterial cell or spore capable of reproducing into a visible colony on a petri dish. The testing method (Petrifilm AOAC 990.12) uses standardized growth media to culture and count these colonies.

Plants grow in soil, which teems with microbes. Even after washing and drying, some environmental bacteria remain on botanical materials. The question isn't whether bacteria exist but whether harmful pathogens are present and whether total counts exceed safe thresholds. Research on herbal safety suggests that total aerobic counts below 10 million CFU/G pose minimal risk.²

What Each Microbial Test Measures:

• Total Plate Count: All aerobic bacteria present (both harmless and potentially harmful)
• Yeast: Fungal organisms that can spoil herbs in humid conditions
• Mold: Filamentous fungi that produce visible growth and potential mycotoxins
• Total Coliform: Indicator bacteria suggesting fecal contamination or poor sanitation
• E. coli: Specific pathogen indicating direct fecal contamination
• Salmonella: Disease-causing bacteria tested using PCR for rapid detection

 

The testing method (#C55 AOAC 2015.01) uses inductively coupled plasma mass spectrometry (ICP-MS), which can detect metals at extremely low concentrations. This sensitivity allows labs to catch contamination long before it reaches harmful levels.

Why Heavy Metal Limits Vary: Different regulatory bodies set different thresholds. AHPA recommends limits based on daily consumption patterns. WHO guidelines consider cumulative exposure from all dietary sources. More restrictive limits (like California Prop 65) aim to minimize any measurable risk over a lifetime of exposure. Labs typically test to the strictest standard applicable to their market.

All four metals in our peppermint tested well below their respective limits. Cadmium was not detected at all, meaning concentrations fell below the instrument's detection threshold. These results confirm that the growing conditions and soil quality produced a clean crop without significant heavy metal accumulation.

Foreign Material Inspection: Purity Standards

The foreign material section verifies physical purity. Labs examine samples visually and with metal detectors to identify non-botanical contaminants. Foreign material falls into two categories: organic and inorganic.

Organic foreign material includes plant parts from other species, insect fragments, animal waste, or non-target portions of the correct plant (like stems mixed into leaf-only material). Our peppermint tested at less than 2.0% pieces by weight, meaning more than 98% of the sample consisted of pure peppermint leaf.

Inorganic foreign material covers soil, sand, rocks, glass, and metal fragments. The COA specifies detection limits: less than 4.0mm ferrous (iron-based), nonferrous (non-magnetic metals like aluminum), and stainless steel. Any metal fragments larger than 4mm would trigger a failure. Our peppermint passed with less than 2.0% inorganic material by weight.

Physical contaminants enter botanical materials during harvest, processing, or packaging. Proper cleaning, sifting, and metal detection eliminate most problems, but batch testing confirms these quality control steps worked as intended.

Certifications and Compliance Notes

The certifications section lists any special designations for the lot. Our peppermint is certified kosher, meaning it was processed according to Jewish dietary law under rabbinical supervision. Other certifications you might see include USDA Certified Organic, wildcrafted (harvested from natural habitats), or Fair Trade.

The bottom of our COA includes compliance statements: "No pesticides were used to grow this product. This product is free of any additives or preservatives. No solvents were used to produce this product, nor excipients."

These declarations address common concerns about botanical processing. Some herbs undergo solvent extraction to concentrate active compounds. Others receive preservatives to extend shelf life or flowing agents to improve handling. Our peppermint contains none of these additives. What you see is what you get: leaves, steam treatment, and nothing else.

Storage instructions appear here too: "Store under cool, dry conditions in sealed container." This guidance isn't arbitrary. Heat and humidity degrade volatile oils and promote microbial growth. Exposure to air oxidizes delicate compounds. Proper storage preserves the quality documented in the COA throughout the product's shelf life.

Red Flags to Watch For in Any COA

Now that you understand what a passing COA looks like, you should know which warning signs indicate problems. Not every company provides transparent testing, and not every COA meets the same standards.

Missing Information: A legitimate COA includes testing methods, lot numbers, and pass/fail determinations. If any of these elements are absent, question the document's validity. Generic COAs that don't reference specific batch numbers or manufacture dates may not represent the actual product you received.

Failed Tests: Any result marked "FAIL" means the product exceeded safety limits. Microbial counts above thresholds suggest contamination or poor handling. Heavy metals above limits indicate unsafe exposure levels. Herbal suppliers should never release failed lots to consumers.

No Pathogen Testing: A COA that lists total plate count but omits E. coli and Salmonella testing is incomplete. Total counts tell you about overall microbial load, but only specific pathogen tests confirm the absence of issue-causing organisms.

Suspiciously Perfect Results: While passing all tests is ideal, results that show exactly zero for every measurement or round numbers across the board may indicate fabricated data. Real lab results include decimal places, detection limits, and some natural variation between samples.

Outdated Testing: Check the manufacture date and retest date. If the COA predates your purchase by years, you're not viewing results for your specific lot. 

Missing AOAC Methods: Reputable labs cite standardized testing protocols. AOAC International methods are industry standard for food and botanical analysis. ISO methods are also acceptable. If testing methods aren't listed or reference proprietary procedures, you can't verify that appropriate scientific protocols were followed.

How We Use COAs at Sacred Plant Co

Every herb we stock undergoes third-party testing before we accept delivery. We review COAs for every incoming lot and reject any material that fails microbial, heavy metal, or purity standards. Suppliers who consistently deliver clean material earn our continued business. Those who ship contaminated lots lose it.

Once herbs pass inspection and reach our facility, we assign batch numbers and print labels with QR codes. Scanning the code on your bag pulls up the exact COA for your lot. This system ensures full traceability from farm to cup. If you brew peppermint tea, you can verify that the leaves in your infuser came from lot PPRL5202, grown and tested exactly as documented.

We store COAs indefinitely in our database. Even years after purchase, you can return to the QR code and review the original test results. This permanent record supports transparency and gives you reference material if you want to compare testing between different lots or suppliers.

Some companies test only the first batch of a new herb and then skip testing for subsequent lots. We test every single batch because growing conditions change, weather affects harvests, and processing variables introduce risk. Batch-specific testing costs more, but it catches problems before they reach customers.

Comparing Testing Standards Across Suppliers

Once you know how to read a COA, you can compare quality across different herbal suppliers. Not all companies test to the same standards or provide equal transparency. Here's what to look for when evaluating competitors:

Testing Frequency: Does the company test every batch or only sample batches? Consistent testing demonstrates commitment to quality. Sporadic testing suggests cost-cutting.

Heavy Metal Thresholds: Some suppliers use lenient limits that would fail under stricter regulatory frameworks. Compare the listed limits to AHPA recommendations or California Prop 65 standards. Lower limits indicate more conservative safety margins.

Pathogen Screening: Basic testing might skip Salmonella or use less sensitive detection methods. PCR testing (like the BAX method in our COA) detects pathogens more reliably than older culture-based techniques.

Accessibility: Can you easily access COAs before purchasing? QR codes on individual bags provide better traceability than batch numbers you must email to request. Some companies hide COAs behind customer service requests or provide only generic summaries rather than full lab reports.

Lab Accreditation: Third-party labs should hold ISO 17025 accreditation, which verifies their competence to perform specific tests. In-house testing by the supplier raises questions about objectivity and conflicts of interest.

Accessing Your COA

Every bag we ship includes a QR code printed on the label. Use your smartphone camera to scan the code. It will open a webpage displaying the information about your herb and acces to a full certificate of analysis for your specific lot number. You don't need to download an app or create an account. 

We encourage you to save or print COAs for your records, especially if you're using herbs therapeutically and want to track which batches worked best for you. Lab results provide objective data you can share with healthcare practitioners who may be unfamiliar with botanical quality standards.

Understanding certificates of analysis transforms you from passive consumer to informed herbalist. When you know what to look for, you can verify safety, compare quality.