SOP-002: Accelerated Stability Testing

1. Purpose

This procedure establishes the protocol for conducting accelerated stability testing on cosmetic emulsions using elevated temperatures. Accelerated testing reveals potential stability issues early in product development and helps predict long-term behavior.

2. Scope

This SOP applies to all cosmetic emulsions during development and quality control phases. Accelerated testing supplements but does not replace real-time stability testing.

3. Temperature Selection

Temperature	Application	Duration
37°C (98.6°F)	Standard screening, gentle stress	8-12 weeks
40°C (104°F)	Most common accelerated condition	8-12 weeks
45°C (113°F)	Aggressive screening, rapid results	4-8 weeks

Selection Guide: Use 40°C for standard testing. Use 45°C for rapid screening of prototype formulations. Use 37°C for products with heat-sensitive ingredients.

4. Equipment Requirements

Temperature-controlled incubator or stability chamber
Calibrated thermometer or temperature logger
pH meter (calibrated)
Viscometer (appropriate for product viscosity range)

5. Sample Requirements

Minimum 6 units per batch (one per timepoint)
Samples in final market packaging
Control samples stored at ambient (20-25°C) for comparison
Proper labeling with batch number and sample ID

6. Evaluation Schedule

Timepoint	Duration	Action
T0	Day 0	Initial evaluation before incubation
T1	1 Week	Visual check, pH if indicated
T2	2 Weeks	Full evaluation
T3	4 Weeks	Full evaluation
T4	8 Weeks	Full evaluation
T5	12 Weeks	Final evaluation

7. Evaluation Parameters

7.1 Physical Appearance

Observe for: phase separation, creaming, sedimentation, oil/water separation, syneresis (water release)

7.2 Color Changes

Document: yellowing, browning, fading, color migration

7.3 Odor Changes

Evaluate: rancidity, chemical notes, fragrance degradation, off-notes

7.4 pH Drift

Measure and compare to T0. pH drift may indicate chemical degradation or preservative instability.

7.5 Viscosity Changes

Significant thickening or thinning indicates emulsion stress or polymer degradation.

Important: Elevated temperatures do NOT sterilize products. Accelerated testing often reveals preservation weaknesses by accelerating pH drift or other changes that compromise the preservative system.

Product Name:
Batch/Lot Number:
Test Start Date (T0):
Storage Temperature:	☐ 37°C ☐ 40°C ☐ 45°C
Incubator ID: