I am analyzing Lycopene using LC-MS. I use a C18 column and my mobile phase is Methanol: MTBE = 95:5. I use an Agilent Ultivo QQQ mass spectrometer with APCI negative ion mode. I see the precursor ion at 536.4 as expected and I see the major product ion at 467.3 with a collision energy 22 V ([M-69]-, this fragment is reported in the literature and commonly used in MRM). In addition, I see another peak at collision energy 10 V at 535.8. This is also very prominent and consistent. I like to identify this peak and see whether I can use it as a qualifier. Please give your suggestions for a possible structure for this ion. Can it simply be [M-H]-?