Table 3.

Correlation coefficient (r2), rate constant (K), and half-time (t1/2) obtained by fitting the data of the release of HA from HAN into 0.08 M Na2CO3 and in phosphate-buffered solution at pH 7.4 and pH 4.8

Aqueous solution	Saturation release (%)	r2			Rate constant (k)	t1/2 (hours)
		First-order	Pseudo-second order	Bhaskar equation
Na2CO3	95.7	0.9865	0.9907	0.9802	0.001 g mg−1 · h−1,a	9.35a
pH 7.4	56.4	0.9937	0.9252	0.9817	0.012 h−1,b	57.8b
pH 4.8	99.8	0.7361	0.1298	0.8133	_	0.09c

^aNotes: Estimated using pseudo-second order kinetics;

^bestimated using first-order kinetics;

^cestimated using the Bhaskar equation.