. 2020 Dec 30;125(1):411–422. doi: 10.1021/acs.jpca.0c10223

Table 2. Major PTR–TOF–MS Ion Signals Observed During OH Initiated PZ Photo-Oxidation Experiments^a.

exact	ion sum		fragmentation^b
m/z	formula		PZ	PZI	PZNO	PZNO₂	interpretation
44.050	C₂H₆N⁺		1	12	5	13	ring fragment, aziridine
46.029	CH₄NO⁺	*^b					NH₂CHO and isomers from heterogeneous reactions, chamber artefact?
69.045	C₃H₅N₂⁺						imidazole from heterogeneous reactions
74.024	C₂H₄NO₂⁺	*					CHONHCHO, primary product
81.045	C₄H₅N₂⁺	*	?	?			pyrazine, dehydrogenation fragment from [PZI]H⁺ and [PZ]H⁺; PZ impurity?
83.060	C₄H₇N₂⁺	*	2	84			PZ and PZI dehydrogenation fragment
85.076	C₄H₉N₂⁺		3	4	20	30	PZI. fragment of PZ, PZNO, and PZNO₂
86.084	C₄H₁₀N₂⁺				12	38	PZNO and PZNO₂ fragment
87.092	C₄H₁₁N₂⁺		94				PZ
99.055	C₄H₇N₂O⁺	*					dihydropyrazinone isomers, oxidation product of PZI?
99.092	C₅H₁₁N₂⁺	*					unidentified condensation product
115.087	C₅H₁₁N₂O⁺	*					1-formylpiperazine (cond. prod.)
116.082	C₄H₁₀N₃O⁺	*			63		PZNO
132.077	C₄H₁₀N₃O₂⁺	*				15	PZNO₂
177.062	C₄H₉N₄O₄						PZ(NO₂)₂

Only ion signals increasing by more than 2% of the m/z 87.092 ion signal decrease are included. Abbreviations: PZ, piperazine; PZI, 1,2,3,6-tetrahydropyrazine; PZNO, 1-nitrosopiperazine; PZNO₂, 1-nitropiperazine.

Fragmentation in % at E/N = 105 Td. Corresponding molecular formula found by TD-GCMS of Tenax samples, ref (9).

Table 2. Major PTR–TOF–MS Ion Signals Observed During OH Initiated PZ Photo-Oxidation Experimentsa.

Table 2. Major PTR–TOF–MS Ion Signals Observed During OH Initiated PZ Photo-Oxidation Experiments^a.