Testing & Stability Labs

Last verified: March 18, 2026

Independent analytical laboratories that verify supplement identity, potency, purity, and safety. Accredited testing for regulatory compliance, quality assurance, and stability studies including accelerated and real-time shelf-life protocols.

Independent testing is how you prove what's in your product. Stability testing is how you prove it stays that way. This page explains what testing and stability labs do, how to evaluate them, and what separates a credible lab from one that just prints numbers on paper.

Dietary supplement manufacturers must comply with 21 CFR Part 111 (Current Good Manufacturing Practice for dietary supplements). This includes requirements for personnel, facilities, equipment, production, laboratory operations, and record-keeping.

What Testing Is Required Under Part 111

21 CFR Part 111 requires dietary supplement manufacturers to test at multiple stages of production. These are not optional. They are federal requirements.

Stage	What Must Be Tested	CFR Reference
Incoming ingredients	Identity of each lot (every component)	111.75(a)(1)
In-process	Verification that specs are met during production	111.75(b)
Finished product	Identity, purity, strength, composition, contamination	111.75(c)
Packaging and labeling	Correct label for correct product	111.75(g)

Types of Tests and What They Measure

Identity Testing

Measures: Confirms the ingredient is what it claims to be

Methods: HPTLC, HPLC, DNA barcoding (for botanicals), FTIR

Why it matters: Prevents wrong ingredients from entering your product. The most fundamental quality test.

Potency / Assay Testing

Measures: Quantifies the amount of active ingredient per serving

Methods: HPLC, UV-Vis spectrophotometry, titration

Why it matters: Proves your label claims are accurate. Under-potency or over-potency are both compliance failures.

Microbial Testing

Measures: Detects harmful microorganisms (bacteria, yeast, mold)

Methods: Total plate count, USP methods, PCR-based detection

Why it matters: Protects consumer safety. Contamination can cause illness and triggers recalls.

Heavy Metals

Measures: Lead, mercury, cadmium, arsenic levels

Methods: ICP-MS, ICP-OES

Why it matters: Required for California Prop 65 compliance. Many retailers require this for product listing.

Pesticide Residue

Measures: Traces of agricultural chemicals

Methods: GC-MS/MS, LC-MS/MS

Why it matters: Important for botanicals and plant-based ingredients. Required for organic certification.

Stability Study Types

Your expiration date is only as good as the data behind it. Stability testing measures how temperature, humidity, light, and time affect your product's potency, purity, and physical characteristics.

Accelerated Stability

Elevated conditions (40°C/75% RH) for 3-6 months. Predicts product behavior under stress. Used for preliminary shelf-life estimates and to identify potential degradation pathways early. Results available faster but less precise than real-time data.

Real-Time (Long-Term) Stability

Normal storage conditions (25°C/60% RH) for 12-36 months. The most accurate predictor of actual shelf life. Required for final expiration date assignment. Typically run in parallel with accelerated studies.

Intermediate Stability

Moderate conditions (30°C/65% RH) for 12 months. Used when accelerated data shows significant change, providing additional data between accelerated and long-term conditions. Helps refine shelf-life predictions.

Photostability

Measures degradation from light exposure. Critical for light-sensitive ingredients (B vitamins, omega-3s, certain botanicals). Tests both the product and the packaging's ability to protect against light.

How to Evaluate a Testing Lab

ISO/IEC 17025 accreditation: This is the gold standard for testing laboratories. It means the lab's methods, equipment, and personnel have been validated by an independent accreditation body. Check A2LA or ANAB directories to verify.
Scope of accreditation: A lab can be ISO 17025 accredited for some tests but not others. Check that their accreditation covers the specific tests you need. An accredited microbial lab may not be accredited for heavy metals.
Experience with dietary supplements: Not all analytical labs specialize in supplements. Look for labs that routinely handle botanical identification, USP reference standards, and Part 111 requirements.
Stability chamber capabilities: For stability testing, chambers must maintain precise temperature and humidity. Ask about chamber calibration frequency, monitoring systems, and what happens during power outages. ICH-compliant chambers are the standard.
Turnaround time and communication: Standard turnaround is 5 to 10 business days. The lab should provide clear timelines and communicate proactively about delays or out-of-spec results.
COA format and detail: Request a sample COA before you commit. It should include method references, specification limits, actual results, and authorized signatures. Template or minimal COAs are a yellow flag.

Disclaimer: This page is educational content, not professional advice. Testing and stability requirements vary by product, ingredients, and regulatory jurisdiction. Consult qualified professionals. See our Terms of Service for details.

Frequently Asked Questions

What accreditations should a supplement testing lab have?

Look for ISO/IEC 17025 accreditation, which validates the lab's testing methods and quality management system. FDA registration is also important. Some labs carry additional accreditations like A2LA or state-specific certifications. An unaccredited lab's results carry less weight with regulators and retailers.

What is the difference between in-house and third-party testing?

In-house testing is performed by the manufacturer's own lab during production. Third-party testing is done by an independent lab with no financial relationship to the manufacturer. Both serve different purposes: in-house for production quality control, third-party for independent verification. The strongest quality programs use both.

What is the difference between accelerated and real-time stability testing?

Accelerated stability testing subjects samples to elevated temperature and humidity (typically 40°C/75% RH) for 3-6 months to predict long-term behavior. Real-time testing stores samples under normal conditions (25°C/60% RH) for 12-36 months. Accelerated testing is faster but real-time testing is more accurate. Most programs use both.

How long does supplement testing take?

Standard turnaround for identity, potency, and microbial testing is 5 to 10 business days. Heavy metals testing adds 3 to 5 days. Stability studies take 3 to 6 months (accelerated) or 12 to 24 months (real-time). Rush testing is available from most labs at premium pricing.

How much does third-party supplement testing cost?

Basic COA testing (identity, potency, microbial) costs $500 to $1,500 per batch. Heavy metals panels add $200 to $500. Full panels including pesticides and solvents can run $2,000 to $3,500. Stability studies cost $3,000 to $8,000 per product. Pricing varies by lab and number of analytes.

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