Ensuring the quality, purity, and safety of glutathione is critical—especially for products used in pharmaceuticals, dietary supplements, cosmetics, or clinical settings. Rigorous quality control (QC) tests are essential to validate that each batch of glutathione meets regulatory requirements, label claims, and end-use expectations.
This article outlines the key QC tests used during glutathione production and release, offering insight into their purpose, procedures, and what buyers should look for on a Certificate of Analysis (COA).
HPLC for Purity and Content Analysis
High-performance liquid chromatography (HPLC) is the gold standard for determining glutathione content and purity.
What It Measures:
- Content of reduced glutathione (GSH)
- Impurities or related compounds
- Retention time and peak purity
Heavy Metals Testing (ICP-MS or AAS)
Testing for toxic heavy metals like arsenic, cadmium, lead, and mercury ensures product safety.
Acceptable Limits (per USP or EP):
- Lead: ≤ 0.5 ppm
- Arsenic: ≤ 1.5 ppm
- Cadmium: ≤ 1 ppm
- Mercury: ≤ 0.1 ppm
Microbiological Testing
Microbial limits are especially important for glutathione used in oral supplements or injectable applications.
Tests Include:
- Total plate count
- Yeast and mold
- E. coli, Salmonella, Staphylococcus aureus
Moisture Content and Loss on Drying
Moisture affects shelf life and flowability. Loss on drying (LOD) measures water and volatile content in the sample.
Common Methods:
- Gravimetric drying at 105°C
- Infrared drying analyzers
- Karl Fischer titration (for very low moisture)
Residual Solvent Testing (if applicable)
If the glutathione was synthesized using solvents, gas chromatography (GC) ensures residual levels are below safety thresholds.
Typical Solvents Screened:
- Ethanol
- Methanol
- Acetone
- Dichloromethane
Conclusion
Whether you are sourcing glutathione for supplements, skincare, or clinical use, understanding these essential QC tests ensures you receive a product that is safe, compliant, and effective.
When reviewing COAs or qualifying suppliers, always verify that these key tests have been performed and meet the required specifications. Working with suppliers who follow cGMP protocols and provide third-party test results is a strong indicator of reliability and product quality.
To learn more about L-Glutathione knowlege, refer to our article on The Ultimate Guide to Glutathione Powder