Reviewed and Approved by Matt Traynor, PhD, Vice President, Innovation and Validation, Certified Laboratories
1-Minute Summary
- Vitamin C is a popular but unstable compound in skincare, requiring accurate content verification to support label claims.
- In the U.S., the product’s stated label claim (e.g. 15% Vitamin C) must be truthful and not misleading, or else the product can be considered misbranded by regulators.
- It’s best practice to test identity, purity, potency, strength, and potential contaminants of Vitamin C in finished goods.
- Stability testing helps determine shelf life, prevent product degradation, and ensure a positive consumer experience.
The Rise of Vitamin C in Cosmetics
Vitamin C is everywhere in skincare right now thanks to its ability to support overall appearance and health. You see it in serums, moisturizers, brightening creams, sheet masks, and even hair care. Brands label their products with claims like “15% Vitamin C” and specify the form, whether it is L‑ascorbic acid or another derivative.
And, with projections like these, it’s easy to see why brands are leaning into this popular compound:
- In 2023, the global Vitamin C serum market was about USD 1.27 billion, and it is projected to reach USD 2.10 billion by 2030, growing at a compound annual growth rate (CAGR) of 7.6%.
- The U.S. Vitamin C skincare segment is expected to grow from USD 1.49 billion in 2023 to about USD 2.22 billion by 2032 at 4.5% CAGR.
That steady growth is a great opportunity for cosmetic makers. But it also comes with responsibility. If you make a claim like “15% Vitamin C” on your label, you need to back it up with reliable data. Let’s walk through the process.
Regulatory and Consumer Trust Requirements
First, as with so much in this industry, let’s start with the regulations.
In the U.S., the Food, Drug, and Cosmetic Act (FD&C Act) sets the foundation for regulations of cosmetic products:
- Cosmetics must not be adulterated (unsafe, contaminated, or manufactured under insanitary conditions) or misbranded (with false or misleading labeling).
- “Misbranding” means a claim like “15% Vitamin C” on the label must be truthful, or else the product is considered misbranded and open to regulatory action.
In 2022, the Modernization of Cosmetic Regulation Act (MoCRA) was enacted, which amends the FD&C Act:
- Explicitly requires companies to substantiate product safety before selling cosmetics.
- Companies must maintain records that provide adequate safety substantiation. So, rather than simply avoiding false claims, you now must have scientific evidence to substantiate safety.
In the EU, Regulation (EC) 1223/2009 sets similar expectations.
Given the volatility of supply chains and the increased prevalence of economic adulteration of raw materials, it’s best practice to test your raw materials for identity, purity, potency, strength, and potential contaminants prior to use.
This is required in the dietary supplements industry, and it’s a good idea for cosmetic brands to follow suit to build a reputation of trust with regulators and consumers.
Why Testing Vitamin C Is Essential
Laboratory testing of Vitamin C is especially important given its inherent instability. It reacts easily with oxygen, heat, and light, and it can break down in the presence of metals like iron or copper. That means your Vitamin C can degrade long before it ever reaches the consumer.
You may notice this as a visible color change from clear to yellow or brown. Less obvious is the drop in potency that affects the product’s effectiveness. Without testing, you cannot guarantee that the concentration listed on your label matches what the consumer will actually get. This can lead to disappointed customers and harm your brand reputation.
Testing makes sure your label is truthful, your safety substantiation is solid, and your customers can trust the product they are buying.
What Goes into Testing Active Vitamin C
Vitamin C testing is common at Certified Laboratories since we also test supplements in addition to cosmetics, personal care products, and OTC drugs. Our capabilities include…
- Identity testing to ensure the raw material is the correct form of Vitamin C.
- Potency or strength analysis to quantify precisely how much Vitamin C is resent.
- Purity and contaminant screening to ensure nothing unwanted is in the mix (e.g. heavy metals or microbial contamination).
At Certified Laboratories, we perform Vitamin C testing using an internal method that is validated for cosmetic matrices; however, revalidation may be required for some samples. If needed, we also offer the official USP method upon request. Here are the details about our Vitamin C method:
- Instrumentation: HPLC (High-Performance Liquid Chromatography), known for its precision and specificity.
- Limit of Detection (LOD): 5 ppm
- Limit of Quantitation (LOQ): 15 ppm
- Reporting units: Results can be provided in %, mg/g, or mg per serving size, based on the customer’s preference. Just let us know your preferred unit when submitting samples.
The Shelf-Life Challenge of Vitamin C
So, you’re confident in your product’s performance when it leaves the facility. But how does it behave during transport and storage?
As mentioned, oxidation often causes noticeable color changes and decreases potency. This process accelerates if products are stored in clear bottles, exposed to heat, or left sitting too long during shipping.
To reduce these risks, many companies:
- Use opaque or amber packaging to protect against light.
- Add an expiration date or “best by” statement to give consumers confidence.
- Perform stability testing to confirm how long the product maintains its effectiveness.
The Role of Stability Testing in Vitamin C Testing
In-package stability testing simulates real-world storage conditions such as temperature, humidity, and light exposure. This allows you to track how Vitamin C degrades in your product over time.
The data gleaned from an in-package stability study helps you…
- Establish a scientifically supported expiration or “best by” date.
- Avoid wasted product due to premature spoilage.
- Provide valuable insights for R&D, such as which packaging and formulations protect Vitamin C best.
- Build a robust testing program to satisfy regulatory requirements for safety substantiation.
Certified Laboratories operates more than 100 calibrated stability chambers that offer ICH (International Council for Harmonisation) testing conditions. Our stability testing team can help you design a study protocol by selecting the number of replicates and time points to provide the data you need within your timeframe and budget.
Use our Stability Testing Questionnaire to get a quote.
Get Help Substantiating Your Product Safety
Vitamin C offers much promise for brands to expand market reach and help consumers. But ensure you’re positioned to leverage its popularity through lab testing and safety substantiation, as required by MoCRA and other global regulations.
Certified Laboratories offers ISO 17025-accredited labs for testing your cosmetic, personal care, OTC drug, and supplements products. Talk to our team about putting our validated methods and expertise to work for you.