Madhusudanan K P, Kumar B, Pathak R, Pant C S, Shaw A K
Regional Sophisticated Instrumentation Centre, Central Drug Research Institute, Lucknow-226 001, India.
Rapid Commun Mass Spectrom. 2003;17(8):816-24. doi: 10.1002/rcm.983.
The tandem mass (MS/MS) spectra of ammonium ion, metal ion and ligated metal ion adducts of chain-extended acyclic nitro-containing deoxyglucose and deoxygalactose derivatives have been studied. The ammonium adducts fragment primarily by elimination of ammonia followed by acetic acid, thus not giving much structural information. In contrast, cationization of these compounds by metal ions and ligated metal ions gave structurally informative and useful fragment ions on MS/MS. The metal ions and ligated metal ions play an important role in controlling and directing fragmentation. Retro-aldol fragmentation is facilitated by metal ions such as Li(+), Na(+), Ag(+) and Cu(+), whereas the adducts with higher alkali metal ions such as Rb(+) and Cs(+) fragment to give only the corresponding metal ions. The divalent metal ions such as Cu(2+) and Ba(2+) also induce retro-aldol fragmentation. However, the charge is carried by the aldehyde fragment in the case of Cu(2+) adducts, whereas the nitroalkane fragment carries the charge in the case of Ba(2+) adducts. Ligated metal ions such as ZnCl(+), CuCl(+), InCl(2) (+) and BaCl(+) also behave similarly and induce retro-aldol fragmentation in these acyclic sugars. Both the metal ion and ligated metal ion adducts can fragment by elimination of metal-containing neutral molecules.
对链延长的无环含硝基脱氧葡萄糖和脱氧半乳糖衍生物的铵离子、金属离子和配位金属离子加合物的串联质谱（MS/MS）进行了研究。铵加合物主要通过消除氨然后消除乙酸进行碎片化，因此没有提供太多结构信息。相比之下，这些化合物通过金属离子和配位金属离子进行阳离子化，在MS/MS上产生了具有结构信息且有用的碎片离子。金属离子和配位金属离子在控制和引导碎片化方面发挥着重要作用。Li(+)、Na(+)、Ag(+)和Cu(+)等金属离子促进逆羟醛碎片化，而与Rb(+)和Cs(+)等高碱金属离子的加合物仅碎片化生成相应的金属离子。Cu(2+)和Ba(2+)等二价金属离子也会诱导逆羟醛碎片化。然而，在Cu(2+)加合物的情况下，电荷由醛片段携带，而在Ba(2+)加合物的情况下，硝基烷片段携带电荷。ZnCl(+)、CuCl(+)、InCl(2) (+)和BaCl(+)等配位金属离子也表现出类似行为，并在这些无环糖中诱导逆羟醛碎片化。金属离子和配位金属离子加合物都可以通过消除含金属的中性分子进行碎片化。
