Electrospray ionization mass spectrometry of AZT H‐phosphonates conjugated with steroids

Abstract

AZT H-phosphonates conjugated with steroids were synthesized and determined by positive and negative ion electrospray ionization mass spectrometry (ESI-MS) in conjunction with tandem mass spectrometry (MS/MS). The fragmentation pathways were investigated in detail. There are very different characteristic fragment ions in the positive and negative ion MS/MS spectra. The azide group of compounds 6a and 6b underwent either elimination of HN(3) or rearrangement to an amine in both positive and negative ion mass spectrometry.

A novel rearrangement in electrospray ionization multistage tandem mass spectrometry of amino acid ester cyclohexyl phosphoramidates of AZT

“…A possible fragmentation pathway of [M + Na] + is shown in Scheme . The fragment ion at m / z 497 was produced by loss of a molecule of cyclohexene, and that at m / z 469 with an additional loss of N 2 , a similar fragmentation pattern to that observed previously for other azido‐containing compounds 12. The ions at m / z 352, 324, 309 and 198 arose from the [M + Na] + ion by loss of a molecule of amino acid ester and cyclohexene.…”

Characteristic fragmentation behavior of tobacco‐specific N‐nitrosamines using electrospray ionization multistage tandem mass spectrometry incorporating deuterium labeling

“…Furthermore, the ESI‐MS n of deutero‐labeled TSNA compounds is used to support the proposed identities of the product ions and therefore the mechanism. Identification of the ways in which such kinds of compounds reorganize into small fragments may provide some useful information and guidance to monitor their metabolisms in the biological system …”

“…Identification of the ways in which such kinds of compounds reorganize into small fragments may provide some useful information and guidance to monitor their metabolisms in the biological system. [20,21] EXPERIMENTAL MS n characteristic fragmentation behavior of tobacco-specific N-nitrosamines (and TSNA-d4) was achieved using an LCQ ™ Deca XP Plus ion trap mass spectrometer (Thermo, USA) utilizing electrospray ionization (ESI), which is capable of analyzing ions up to m/z 6000. The scan range was generally from m/z 50 to 250.…”

Characteristic fragmentation behavior of phosphoamino acid conjugates with 3′‐azido‐3′‐deoxythymidine by electrospray ionization tandem mass spectrometry

“…4) and a possible fragmentation pathway is shown in Scheme . A significant difference is that the azido group was rearranged to an amino group after expulsion of a molecule of N 2 , which resulted in formation of a novel substituted aziridine 11,12. It is interesting that the aziridine moiety showed high stability and did not undergo further fragmentations in ESI‐MS 2 .…”