Table 3.

Kinetic models for vitamin D3 degradation under different conditions.

	Light		Oxygen		Other Conditions *
					DW		Cu2+		pH = 1
Model	R 2	AIC	R 2	AIC	R 2	AIC	R 2	AIC	R 2	AIC
0.order: y = 100 − k × t	0.906	344.8	0.947	475.6	0.892	164.8	0.758	109.8	0.826	102.6
1.order: y = 100 ∗ exp(−k × t)	0.796	379.4	0.918	505.0	0.982	127.3	1.000	14.30	0.995	61.45
2.order: y = 100/(1 + k × t)	0.698	397.1	0.843	549.0	0.903	162.5	0.986	75.55	0.989	69.02
Weibull:y = 100 ∗ exp(−(t/λ)^k)	0.994	225.7	0.973	431.8	0.997	89.28	1.000	1.616	0.998	52.43

R²—coefficient of determination; AIC—the Akaike information criterion; k—slope (rate constant); t—time [h]; λ—scale parameter; k—shape parameter; * representative data provided for distilled water, Cu²⁺ ions, and pH = 1.