Quantitative analysis of isomeric ion mixtures

✍ Scribed by Mei-Yi Zhang; Fred W. McLafferty

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 405 KB
• Volume: 27
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210271006

✦ Synopsis

Several approaches have been proposed for the use of mass spectra from collisionally activated dissociation (CAD) to determine the isomeric composition of mass analyzed ions. As originally proposed, measurement at collision gas pressures ( z 30% transmittance) yielding maximum CAD cross-sections provides improved precision, whereas differential isomeric scattering should not be an appreciable problem, despite earlier warnings. For the C,H,O+ ' ions from butan-l,fdiol, this CAD method found [CH,CHO"'J = 50 _+ 4%, in agreement with values of 44 _+ 6 and 45 2 6% from two methods of neutralization-reionization mass spectrometry, but in contrast with 66 5% from a proposed CAD methodology using high transmittance measurements. The agreement of the three methods also shows that the principle of linear superposition of spectra is applicable to CAD as well as to electron ionization mass spectra.