Arrhenius Equation: k = A · exp(-Ea / RT) where R = 8.314 J/(mol·K), T in Kelvin t90 (time to 90% potency): t90 = -ln(0.90) / k = 0.105 / k Temperature Acceleration Factor: AF = exp[(Ea/R) · (1/T1 - 1/T2)] Q10 Rule (approximate): Q10 ≈ exp[(Ea·10) / (R·T1·T2)] Humidity Correction (simplified): k_eff = k · (1 + 0.02 · RH/100) Expiry Date (25°C): t_expiry = t90(25°C) · (assay_init - spec) / (100 - spec)