Size effect on fragmentation in tandem mass spectrometry.
The collision energy or collision voltage necessary to obtain 50% fragmentation (characteristic collision energy/voltage, CCE or CCV) has been systematically determined for different types of molecules [poly(ethylene glycols) (PEG), poly(tetrahydrofuran) (PTHF), and peptides] over a wide mass (degrees of freedom) range. In the case of lithium-cationized PEGs a clear linear correlation (R(2) > 0.996) has been found between CCE and precursor ion mass on various instrument types up to 4.5 kDa. A similar linear correlation was observed between CCV and the mass-to-charge ratio. For singly and multiply charged polymers studied under a variety of experimental conditions and on several instruments, all data were plotted together and showed correlation coefficient R(2) = 0.991. A prerequisite to observe such a good linear correlation is that the energy and entropy of activation in a class of polymers is likely to remain constant. When compounds of different structure are compared, the CCV will depend not only on the molecular mass but the activation energy and entropy as well. This finding has both theoretical and practical importance. From a theoretical point of view it suggests fast energy randomization up to at least 4.5 kDa so that statistical rate theories are applicable in this range. These results also suggest an easy method for instrument tuning for high-throughput structural characterization through tandem MS: after a standard compound is measured, the optimum excitation voltage is in a simple proportion with the mass of any structurally similar analyte at constant experimental conditions.
Institute of Structural Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Pusztaszeri ut 59-67, 1025 Budapest, Hungary.
Antony
A
Memboeuf
Andreas
A
Nasioudis
Sergio
S
Indelicato
Ferenc
F
Pollreisz
Akos
A
Kuki
Sándor
S
Kéki
Oscar F
OF
van den Brink
Károly
K
Vékey
László
L
Drahos
D002072:Butylene Glycols / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*
D002072:Butylene Glycols; D010455:Peptides; D011108:Polymers; C524501:poly(tetrahydrofuran); D011092:Polyethylene Glycols