Table 1.

Possible oxidative structures of tested monoterpenes related to observed molecular ions.

Molecular ion	Formula	Change in MW	Oxidative product	Explanation
132	C10H12	M-4	− 4[H]	Loss of 4 hydrogens to form two double bonds from two –CH2–CH2− group
134	C10H14	M-2	− 2[H]	Loss of 2 hydrogens to form an double bond from –CH2–CH2−
136	C10H16	M		Parent compound or its isomers
138	C9H14O	M + 2	+ [O] and −[CH2]	Replacing –CH2- group with an oxygen
150	C10H14O	M + 14	+ [O] and − 2[H]	Formation of C=O group from –CH2−
152	C10H16O	M + 16	+ [O]	Insertion of oxygen between C and H in –CH2− CH2− group to form hydroxyl group, or addition of oxygen to a double bond to form epoxide group
154	C10H18O	M + 18	+ [O] and + 2[H]	Addition of OH and H to a double bond