Phosphoramidates of nucleosides are continuing to be an important class of rationally designed therapeutics especially as oligonucleotide analogs employed as antisense and antigene agents. A series of different nucleo...Phosphoramidates of nucleosides are continuing to be an important class of rationally designed therapeutics especially as oligonucleotide analogs employed as antisense and antigene agents. A series of different nucleoside 5’-thiophosphoramidates have recently been synthesized, their electrospray ionization mass specra have been investigated. The positive and negative electrospray ionization mass spectra all gave strong pseudomolecular ions and characteristic fragment ions, however, they showed different fragmentation pathways. In the negative ion MS, the deprotonated molecule showed the base peak with loss of propylene. In the positive ion MS, the protonated molecule usually produced ions from loss of water, amino acid methyl ester, methyl alcohol, uridine and phosphoryl group. These mass spectral fragmentation pathways are helpful to determination of similarphosphoramidates of nucleosides.展开更多
车用新鲜及废润滑油样品的傅里叶变换红外光谱(FT-IR)表明,两者中均存在羧基及羟基官能团,即存在酸性组分。利用具有超高分辨率的负离子电喷雾-傅里叶变换离子回旋共振质谱仪(negative-ion ESI FT-ICR MS)分析了车用新鲜及废润滑油中酸...车用新鲜及废润滑油样品的傅里叶变换红外光谱(FT-IR)表明,两者中均存在羧基及羟基官能团,即存在酸性组分。利用具有超高分辨率的负离子电喷雾-傅里叶变换离子回旋共振质谱仪(negative-ion ESI FT-ICR MS)分析了车用新鲜及废润滑油中酸性化合物的组成及分布。结果表明,从新鲜润滑油中鉴定出的酸性化合物主要为O3、O1及O2类,而从废润滑油中鉴定出的酸性化合物则主要为O3、O2、O4及O1类。经对比分析可知,新鲜润滑油中的酸性化合物在废润滑油中均存在,其种类及所占比例基本未发生变化,但绝对含量不同;废润滑油中新产生的O3、O2及O1类酸性化合物种类较多,但其所占比例较小;车用新鲜与废润滑油中酸性组分的显著差异在于后者中产生了前者所没有的O4类化合物,且所占比例较大。展开更多
文摘Phosphoramidates of nucleosides are continuing to be an important class of rationally designed therapeutics especially as oligonucleotide analogs employed as antisense and antigene agents. A series of different nucleoside 5’-thiophosphoramidates have recently been synthesized, their electrospray ionization mass specra have been investigated. The positive and negative electrospray ionization mass spectra all gave strong pseudomolecular ions and characteristic fragment ions, however, they showed different fragmentation pathways. In the negative ion MS, the deprotonated molecule showed the base peak with loss of propylene. In the positive ion MS, the protonated molecule usually produced ions from loss of water, amino acid methyl ester, methyl alcohol, uridine and phosphoryl group. These mass spectral fragmentation pathways are helpful to determination of similarphosphoramidates of nucleosides.
文摘车用新鲜及废润滑油样品的傅里叶变换红外光谱(FT-IR)表明,两者中均存在羧基及羟基官能团,即存在酸性组分。利用具有超高分辨率的负离子电喷雾-傅里叶变换离子回旋共振质谱仪(negative-ion ESI FT-ICR MS)分析了车用新鲜及废润滑油中酸性化合物的组成及分布。结果表明,从新鲜润滑油中鉴定出的酸性化合物主要为O3、O1及O2类,而从废润滑油中鉴定出的酸性化合物则主要为O3、O2、O4及O1类。经对比分析可知,新鲜润滑油中的酸性化合物在废润滑油中均存在,其种类及所占比例基本未发生变化,但绝对含量不同;废润滑油中新产生的O3、O2及O1类酸性化合物种类较多,但其所占比例较小;车用新鲜与废润滑油中酸性组分的显著差异在于后者中产生了前者所没有的O4类化合物,且所占比例较大。
