Ozone Quantification: Two Distinct Metrics
Credible ozone potency requires measuring two fundamentally different quantities: the gas-phase ozone delivered to the reactor (Total Ozone Dose) and the dissolved ozone residual remaining in the finished product.
1. Total Ozone Dose (Process Input)
Total Ozone Dose quantifies the actual mass of ozone delivered to the glycerin, calculated from gas-phase ozone concentration × calibrated flow rate × treatment time. This is measured using UV absorption near 253.7 nm — the reference method for gas-phase ozone — with calibrated flow regulators and continuous logging. Unlike run time alone, Total Ozone Dose accounts for generator output, oxygen purity, and gas transfer conditions.
References: Gordon et al. (1995); Ferré-Aracil et al. (2015); Zhou & Smith (1995)
2. Dissolved Ozone Residual (Product Potency)
Product-side potency is measured by the indigo trisulfonate colorimetric method (Standard Methods 4500-O₃ B / Bader-Hoigné), adapted and validated for the glycerin matrix. Ozone selectively bleaches the blue indigo dye; absorbance change at ~600 nm is proportional to ozone concentration. Because glycerin reacts with ozone through direct and radical pathways (rate constants ~10-1–10-2 L·mol-1·s-1), matrix-specific validation is mandatory.
References: Rakness et al. (2010); Canterino et al. (2009)
What Makes Glycerin Different From Water
Ozone half-life in water: 10–30 minutes. In glycerin: ~90 days at 2–8°C. This extraordinary stabilization occurs because ozone reacts with glycerol C-H bonds to form thermodynamically stable ozonides (~60%) and organic hydroperoxides (~27%). These products accumulate rather than decomposing — which is why ozonated glycerin maintains potency for months, not minutes.
Supporting Process Indicators
ORP and pH provide valuable process context but are not substitutes for ozone-specific quantification.
| Parameter | Role | Method | Why It Matters |
|---|---|---|---|
| ORP (mV) | Process consistency indicator | Hanna Instruments Ag/AgCl electrode (ISO 17025, NIST-traceable) | Confirms oxidizing environment maintained during production. Non-linear, pH-dependent — not convertible to ozone concentration without matrix-specific correlation. |
| pH | Process / stability indicator | Hanna Instruments digital pH (±0.01, NIST-traceable buffers) | Ozone produces carboxylic acids + protons in glycerol → pH drops. Mildly acidic pH (3.5–5.0) confirms ozonation occurred and matches skin’s acid mantle. |
Reference: Suslow (2004)
Microbiological Quality (ISO Cosmetic Standards)
Testing follows internationally recognized ISO cosmetic microbiology methods — not generic thresholds:
- ISO 21149 — Total aerobic mesophilic bacteria (TAMC)
- ISO 16212 — Yeasts and molds (TYMC)
- ISO 22717 — Pseudomonas aeruginosa detection
- ISO 22718 — Staphylococcus aureus detection
- ISO 21150 — Escherichia coli detection
- ISO 18416 — Candida albicans detection
All manufacturing is performed under ISO 5 (Class 100) laminar flow hoods within an ISO 7 cleanroom, following ISO 9001 quality management guidelines. Petri dish plates are used for environmental monitoring of bacterial growth.
Reference: ISO 21149, ISO 16212
Raw Material Purity
Glycerin is verified per the USP-NF Glycerin Monograph — the United States Pharmacopeia standard for pharmaceutical-grade glycerin. Each lot includes:
- Identity testing and assay/strength verification (≥99.7%)
- Limit tests for toxic adulterants: ethylene glycol (EG) ≤0.10% and diethylene glycol (DEG) ≤0.10%
- Supplier Certificate of Analysis (COA) verified against incoming QC acceptance criteria
- Full chain-of-custody documentation
Stability & Shelf Life
Ozone decay in glycerin follows first-order kinetics: C(t) = C₀ × e-kt. The decay rate constant varies with storage temperature:
| Storage Condition | Decay Rate | Approximate Half-Life |
|---|---|---|
| Room temperature (25°C) | k ≈ 0.05 / month | ~14 months |
| Refrigerated (2–8°C) | k ≈ 0.02 / month | ~35 months |
| Frozen (-20°C) | k ≈ 0.005 / month | ~12 years |
For scientifically defensible shelf-life claims, an ICH Q1A(R2)-aligned real-time stability program using at least three primary batches stored at 25°C±2°C / 60%±5% RH with light protection is the recognized standard.
References: González-González et al. (2022); Patent WO2005079818A1; ICH Q1A(R2)
Our Equipment & Process
SimplyO3 uses German-engineered industrial corona discharge ozone generators (304 SS housing, quartz discharge tube, 316 SS electrode) fed with 99.9% certified medical-grade oxygen through 0.5 µm sintered diffusion stones mounted at the base of VEVOR jacketed borosilicate glass reaction vessels. Temperature is held constant at 72°F (22.2°C) via insulated heated blankets. All generators are serviced monthly to maintain consistent output.
Published Sources & Standards
- Canterino, M. et al. (2009). “A Kinetic Investigation on the Ozonation of Glycerol and its Oxygenated Derivatives.” Ozone: Science & Engineering, 31(6), 445–453. doi:10.1080/01919510903244610
- Rakness, K.L. et al. (2010). “Operator-Friendly Technique and Quality Control Considerations for Indigo Colorimetric Measurement of Ozone Residual.” Ozone: Science & Engineering, 32(1), 33–42. doi:10.1080/01919510903467864
- Bin, A.K. (2006). “Ozone Solubility in Liquids.” Ozone: Science & Engineering, 28(2), 67–75. doi:10.1080/01919510600558635
- Ferré-Aracil, J. et al. (2015). “Kinetic Study of Ozone Decay in Homogeneous Phosphate-Buffered Medium.” Ozone: Science & Engineering, 37(4), 330–342. doi:10.1080/01919512.2014.998756
- Gordon, G. et al. (1995). “Minimizing Chlorate Ion Formation.” Journal AWWA, 87(6), 97–108. doi:10.1002/j.1551-8833.1995.tb06382.x
- Suslow, T.V. (2004). “Oxidation-Reduction Potential for Water Disinfection Monitoring, Control, and Documentation.” University of California Division of Agriculture and Natural Resources, Publication 8149.
- Zhou, H. & Smith, D.W. (1995). “Ozone Mass Transfer in Water and Wastewater Treatment: Experimental and Theoretical Studies.” Ph.D. Dissertation, University of Alberta.
- González-González, O. et al. (2022). “Drug Stability: ICH versus Accelerated Predictive Stability Studies.” Pharmaceutics, 14(11), 2324. doi:10.3390/pharmaceutics14112324
- Patent WO2005079818A1 — Glycerol solution containing dissolved ozone. Google Patents
- Patent JP7575652B2 (2024) — Ozone-treated glycerin. Google Patents
- Takeda, Y. et al. (2021). “Inactivation of SARS-CoV-2 by Ozonated Glycerol.” Food and Environmental Virology, 13, 316–323. PMC8233603
- ICH Q1A(R2) — Stability Testing of New Drug Substances and Products. ICH Guidelines
- ISO 21149, ISO 16212, ISO 22717, ISO 22718, ISO 21150, ISO 18416 — Cosmetic microbiology standards. ISO Standards
- Edison Scientific (2026). “Discovery Report: Standardized Ozone Measurement Protocol.” Kosmos Platform.