Table 4.

The observed pseudo-first-order rate constants and half-lives for MTX-cIBR at different pH conditions at 70 °C.

pH	Buffer type	kobs(h−1)	t1/2(h)
1.0	HCl	5.25 × 10−1	1.32
4.0	Acetate	3.2 × 10−3	216.56
5.0	Acetate	1.3 × 10−3	533.08
6.0	Phosphate	9 × 10−4	770.00
7.0	Phosphate	1.2 × 10−3	577.50
8.0	Phosphate	3.1 × 10−3	223.55
10.0	Carbonate	2.3 × 10−2	30.13
12.0	NaOH	7.4 × 10−2	9.29

Ionic strengths of all buffer solutions were adjusted to 0.15 M with NaCl. For pH 1.0, a solution of 0.1 N HCl was used; 0.01 N NaOH was used for pH 12. For all other pH values, buffer concentration was kept at 50 mM.