The MS/MS spectrum of this triply-charged peptide (m/z= 1222.56) fragmented by HCD (Figure ) was also assigned automatically by pLink2 to [ 70 A-K 87 ]-( 1 Z-K 16 ). Only four backbone fragment ions (b3, b4, b6 and y2) derived from the eighteen amino acids peptide [ 70 A-K 87 ] were automatically assigned and several signals remained unassigned.