. Author manuscript; available in PMC: 2026 Feb 17.

Published in final edited form as: Arch Toxicol. 2022 Apr 21;96(6):1865–1880. doi: 10.1007/s00204-022-03294-2

Table 3.

Tentatively identified metabolites of N-piperidinyl etonitazene in urine.

ID	Biotransformation	Formula	m/z (H+) theoretical	m/z (H+) measured	Mass error (ppm)	Retention time (min)	Base peak of MS2 spectrum
P0	Parent drug	C₂₃H₂₈N₄O₃	409.2233	409.2236	0.5	5.48	112.1124
M1	O-dealkylation	C₂₁H₂₄N₄O₃	381.1929	381.1929	0	4.48	112.1124
M2	O-dealkylation + nitro reduction	C₂₁H₂₆N₄O	351.2184	351.2176	−2.3	1.89	112.1124
M3	O-dealkylation + hydroxylation of piperidinyl ring	C₂₁H₂₄N₄O₄	397.1870	397.1870	0	3.99	128.1072
M4	O-dealkylation + ketone on the piperidinyl ring	C₂₁H₂₂N₄O₄	395.1706	395.1715	2.3	5.77	126.0916
M5	O-dealkylation + contraction of piperidinyl ring	C₂₀H₂₂N₄O₃	367.1765	367.1765	0	4.32	98.0969