Competitive kinetics versus stopped flow method for determining the degradation rate constants of steroids by ozonation

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Table 1 Comparison of kinetic rate constants of second order in ultrapure water by competitive kinetic and stopped flow

Compound	μmol L⁻¹	pH, T (°C)	Method of evaluation	Aqueous matrix	Compound of reference	\( {\text{k}}_{{{\text{O}}_{ 3} , {\text{M}}}} \) (L mol⁻¹ s⁻¹)
E2	1.8	6, 20	Competitive kinetics	Spiked water	Phenolate	0.73 × 10^6,*
	3.6	6, 20	Stopped flow	Spiked water	nr	1.58 × 10^6, *
	1	6, 20	Competitive kinetics	Spiked water	Phenol	0.37 × 10^{6, a}
	0.80	6, 20	Competitive kinetics	Spiked water	Phenolate	0.90 × 10^{6, b}
	0.15	6, 20	Absolute rate constant	Spiked water	nr	0.90 × 10^{6, c}
	0.28	6, 20	Absolute rate constant	Natural water	nr	0.99 × 10^{6, c}
	4	6, 20	Competitive kinetics	Natural water	Phenolate	~1.00 × 10^{6, d}
EE2	5.9	6, 20	Competitive kinetics	Spiked water	Phenolate	2.04 × 10^5, *
	11.8	6, 20	Stopped flow	Spiked water	nr	4.00 × 10^5, *
	1	6, 20	Competitive kinetics	Spiked water	Phenol	1.83 × 10^{5, a}
	6.40	6, 20	Competitive kinetics	Spiked water	Phenolate	0.73 × 10^{5, b}
	0.14	6, 20	Absolute rate constant	Spiked water	nr	0.73 × 10^{6, c}
	0.25	6, 20	Absolute rate constant	Natural water	nr	3.16 × 10^{5, c}
	4	6, 20	Competitive kinetics	Natural water	Phenolate	3.16 × 10^{5, d}