Doxycycline Degradation by the Oxidative Fenton Process

Table 4

Molar masses of the main doxycycline degradation products identified by LCMS-IT-TOF at different sampling times during tests carried out under the best operating conditions identified by the RCCD ( = 25 mg/L, = 611 mg/L, and = 35.0°C). (A) Doxycycline, (B–E) main doxycycline degradation products.

Retention time; (s)	Sampling time (s)
	30	60	180	300	600
	Molar mass (g/mol)
41	104 (B)	104 (B)	104 (B)	104 (B)	115
	164	154 (D)	164	186	186
	186	164	186	240	240
	240	184	240	268	268
	269	244	268	306	350
	350	268	350	350	—
	—	306	—	382	—
	—	350	—	432	—
54	142	142	142	142	142
	164	164	262	262	164
	262	262	382	306	262
	382	306	444 (A)	382	306
	444 (A)	382	502 (E)	444 (A)	382
	—	444 (A)	—	502 (E)	404
	—	—	—	—	502 (E)
72	—	74	—	—	—
	—	262	—	—	—
	—	339	—	—	—
	—	399 (C)	—	—	—