The importance of charge-separation reactions in tandem mass spectrometry of doubly protonated angiotensin II formed by electrospray ionization: Experimental considerations and structural implications.

摘要: The occurrence of charge-separation reactions in tandem mass spectrometry doubly protonated angiotensin II is demonstrated by the use mass-analyzed ion kinetic energy (MIKES) and release distributions (KERDs). Linked scans at a constant B/E severely discriminate against product ions formed reactions. Although products are significantly more abundant MIKES experiments, instrumental discrimination still makes quantitation relative abundances highly inaccurate. most probable KERs (T m. p.) average ave.) determined from KERDs, these values compared to peak widths half-height 0. 5). measurement T 5 poor approximation p. ave.. used calculate intercharge distance, which results molecular dynamics calculations. provide evidence with regard mechanisms fragmentation multiply charged location charge site relation decomposition