▁mass ▁of ▁b - ions ▁– ▁ 2 8 ▁( CO ) ▁ ▁Double ▁back bone ▁cle av age ▁produces ▁internal ▁ ions , ▁a cy li um - type ▁like ▁H 2 N - CH R 2 - CO - N H - CH R 3 - CO + ▁or ▁im mon ium - type ▁like ▁H 2 N - CH R 2 - CO - N H += CH R 3 . ▁These ▁ ions ▁are ▁usually ▁disturb ance ▁in ▁the ▁spect ra . ▁ ▁Further ▁cle av age ▁happens ▁under ▁high - energy ▁C ID ▁at ▁the ▁side ▁chain ▁of ▁C - term inal ▁resid ues , ▁forming ▁d n , ▁v n , ▁w n - ions . ▁ ▁Fragment ation ▁rules ▁summary ▁Most ▁fragment ▁ ions ▁are ▁b - ▁or ▁y - ions . ▁a - ions ▁are ▁also ▁frequently ▁seen ▁by ▁the ▁loss ▁of ▁CO ▁from ▁b - ions . ▁ ▁Sat ellite ▁ ions ( wn , ▁v n , ▁d n - ions ) ▁are ▁formed ▁by ▁high - energy ▁C ID . ▁ ▁Ser -, ▁Th r -, ▁Asp - ▁and ▁G lu - cont aining ▁ ions ▁generate ▁neutral ▁mole cular ▁loss ▁of ▁water ▁(- 1 8 ). ▁ ▁As n -, ▁G ln -, ▁L ys -, ▁Arg - cont aining ▁ ions ▁generate ▁neutral ▁mole cular ▁loss ▁of ▁am mon ia ▁(- 1 7 ). ▁ ▁Ne ut ral ▁loss ▁of ▁am mon ia ▁from ▁Arg ▁leads ▁to ▁fragment ▁ ions