Introduction
Certificates of Analysis (CoAs) from third‑party laboratories are the single best tool consumers and retailers have to assess e‑liquid safety and compliance. In the UK in 2026, regulatory and market expectations mean a readable, up‑to‑date CoA is increasingly the norm — but not every report is created equal. This guide explains what to look for, why the details matter, and how to spot common problems so you can trust the products you use or sell.
Key concepts to understand
1. Independent third‑party testing matters
Always confirm that the CoA comes from an independent laboratory with specific experience testing e‑liquids. Vape testing requires specialised methods (for example, testing for thermal degradation products produced during vaping) that general analytical labs may not carry out correctly. Industry guides emphasise using labs with demonstrated vape experience — independent testing reduces conflicts of interest and increases confidence in results (see Kai's Virgin Vapor guide).
2. Limits of Detection (LOD) and reporting limits
The Limit of Detection (LOD) is the lowest concentration an assay can reliably detect. A CoA that lists high LODs can give a false sense of safety because low‑level contaminants may be present but reported as "not detected." Conversely, low LODs provide more useful safety information. Review the CoA for the LODs or reporting limits for each analyte — if they aren’t provided, ask the brand or lab. Industry discussions have shown LODs can be manipulated, so transparent LOD reporting is a key indicator of rigorous testing (Kai's Virgin Vapor discussion).
3. Which contaminants should be screened?
Make sure the CoA includes explicit screening for known vape hazards. At minimum, a thorough report should include:
- Diacetyl and related diketones (e.g., acetyl propionyl)
- Thermal degradation products where applicable (e.g., formaldehyde/formaldehyde‑releasing compounds)
- Heavy metals (lead, cadmium, nickel, chromium)
- Pesticides or botanical contaminants for botanical/CBD products
- Residual solvents from flavour manufacture (e.g., ethyl acetate, methanol)
The UK Tobacco and Related Products Regulations (TRPR) and TRPR summaries emphasise prohibiting ingredients that are carcinogenic, mutagenic or toxic when heated — so look for explicit statements and measured values rather than vague language (UKVapeWorld/TRPR summaries; Canavape/Cali Greens guidance).
4. Nicotine strength and packaging compliance
Verify the labelled nicotine strength against the CoA. Under UK rules, nicotine concentration in e‑liquids sold for vaping must not exceed 20 mg/ml, and nicotine‑containing bottles must be no larger than 10 ml (UK vaping law summaries, 2026). The CoA should list measured nicotine (mg/ml). If you buy nicotine shots or shortfills to mix at home, ensure the combined final concentration will remain ≤ 20 mg/ml.
Examples: when buying nicotine shots to top up a shortfill, check the CoA for both the shot and the shortfill. Brands that publish CoAs for both components reduce the risk of accidental non‑compliance. You can review nicotine‑free or shortfill options such as 0mg Fantasi 100ml Shortfill E‑Liquid 70VG/30PG, or nicotine shots/low‑strength products available from reputable lines like 0-5mg-tick-tock-nicotine-candy-12-drops and the longfill options that include nicotine shots such as 0mg-crystalize-bar-salts-60ml-longfill-50vg-50pg-3x-free-20mg-nicotine-shots-10ml.
5. CBD / hemp products — check the cannabinoid profile and THC limits
For cannabinoid e‑liquids, read the cannabinoid profile on the CoA. The CoA should quantify CBD, CBDA, CBG and THC (and other detectable cannabinoids). UK legal thresholds for THC can be expressed differently depending on product classification: some guidance references 0.2% THC, while other regulatory interpretations express limits as 1 mg THC per finished product — always check MHRA guidance for the product category applicable to your purchase. If THC is present, confirm it is below the applicable legal threshold (Canavape, Cali Greens references).
6. Batch matching and recency
Batch number matching is crucial. A public CoA is useful, but it must match the production batch of the bottle in your hand. Check the CoA for:
- Explicit batch or lot number
- Date of testing
- Product identifier that matches the label (flavour name, nicotine strength, bottle size)
Prefer CoAs that are recent and downloadable, or that can be accessed via a scannable QR code on the product. A CoA for a different batch or an older date is less useful; some brands maintain a public archive of batch‑specific CoAs which increases trust (Cali Greens CoA checklist).
Practical checklist: how to vet a CoA
Use this short checklist when reviewing any e‑liquid CoA:
- Lab independence and vape testing experience stated? (name and accreditation if possible)
- Are methods and instrumentation listed (e.g., GC‑MS, LC‑MS)?
- LOD/reporting limits provided for each analyte?
- Contaminant panel includes diketones, heavy metals, residual solvents, pesticides?
- Measured nicotine matches label and is ≤ 20 mg/ml (and bottle size ≤ 10 ml for nicotine products)?
- For CBD products: full cannabinoid profile listed and THC under UK threshold?
- Batch/lot number and testing date match your product? Is there a QR/downloadable PDF?
Red flags and how to act
Watch out for CoAs that lack key details (no LODs, no batch number, no lab name or accreditation) or that show unusually high LODs across the board. If a CoA is missing or the brand cannot supply batch‑matched documentation, err on the side of caution: seek alternative suppliers or return the product. For retailers, require batch‑matched CoAs from suppliers before listing new lines.
Conclusion
Reading a CoA critically is a skill that protects health and ensures regulatory compliance. Focus on lab independence, transparent Limits of Detection, a full contaminant screen, nicotine and cannabinoid measurements tied to legal limits, and batch matching. Brands that publish clear, downloadable CoAs and state lab accreditation and methods offer greater reassurance — and when buying components to mix (shortfills plus nicotine shots) or CBD e‑liquids, always confirm the relevant CoAs are available and recent. Being diligent about CoAs helps keep vaping safer and keeps your purchases within UK law.
Further reading / resources: Kai's Virgin Vapor guide on vape testing, UK TRPR summaries, MHRA guidance for cannabinoid products, and industry CoA checklists from Canavape and Cali Greens.
