Commonly Lost Fragments Common Stable Ions m-15 .CH3 十 M/z mlz=43 CHs-C=0 m-17 .OH M/e m-26 .CN m-28 H2C=CH2 mlz 91 m-29 .CH2CH3 CHO m-31 .0cH3 m-35 .Cl z=m-1 十 RC0 m-43 CH3C=0 m-45 OCH2CHs m-91 CH2 23:12:5223:12:52