碎片离子峰 + CH3 H3C-CH2 H3C-CH-CH3 H H3C-C-CH3 CH3 43 57 正癸烷 29 71 15 85 99113 142 m/z 23:13:1223:13:12 碎片离子峰 H3C C CH3 CH3 CH3 < H3C CH2 < H3C CH CH3 < m/z 15 29 43 57 85 99 113 142 71 正癸烷