A series of analogs of endomorphin-2 (EM-2) with phenylglycine (Phg) in position 3 or 4 were synthesized. In electrospray ionization Fourier transform ion cyclotron resonance (ESI-Fr-ICR) MS/MS spectra of these ...A series of analogs of endomorphin-2 (EM-2) with phenylglycine (Phg) in position 3 or 4 were synthesized. In electrospray ionization Fourier transform ion cyclotron resonance (ESI-Fr-ICR) MS/MS spectra of these compounds, some b, y, a, and internal ions were observed and slight mass differences between the calculated and observed results are obtained. Their sequences were derived successfully. However, the MS/MS patterns of these analogs with Dphg and Lphg were very similar. It is hard to distinguish them by MS/MS spectra. Moreover, if the third position was substituted by phenylglycine (L or D), a rearrangement could occur in MS/MS experiment to lose proline residue.展开更多
负离子电喷雾-傅里叶变化离子回旋共振质谱仪(Neg ESI FT-ICR MS)具有超高的分辨率,可用于分析重油中杂原子化合物的组成及分布。运用Neg ESI FT-ICR MS,研究委内瑞拉奥里常渣减黏裂化反应前后杂原子化合物,建立了分子组成的解析方法。...负离子电喷雾-傅里叶变化离子回旋共振质谱仪(Neg ESI FT-ICR MS)具有超高的分辨率,可用于分析重油中杂原子化合物的组成及分布。运用Neg ESI FT-ICR MS,研究委内瑞拉奥里常渣减黏裂化反应前后杂原子化合物,建立了分子组成的解析方法。结果表明,常渣中O2类化合物的相对丰度最大,减黏产物中N1类化合物的相对丰度最大。不同缩合度,质荷比小的O2类化合物减黏裂化反应后显著增加。委内瑞拉常渣及其减黏产物中相对丰度最强的O2类化合物均是双环环烷酸。减黏裂化反应使得O2类化合物发生了裂化反应,生成碳数更少、分子质量更小的化合物。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A series of analogs of endomorphin-2 (EM-2) with phenylglycine (Phg) in position 3 or 4 were synthesized. In electrospray ionization Fourier transform ion cyclotron resonance (ESI-Fr-ICR) MS/MS spectra of these compounds, some b, y, a, and internal ions were observed and slight mass differences between the calculated and observed results are obtained. Their sequences were derived successfully. However, the MS/MS patterns of these analogs with Dphg and Lphg were very similar. It is hard to distinguish them by MS/MS spectra. Moreover, if the third position was substituted by phenylglycine (L or D), a rearrangement could occur in MS/MS experiment to lose proline residue.
文摘负离子电喷雾-傅里叶变化离子回旋共振质谱仪(Neg ESI FT-ICR MS)具有超高的分辨率,可用于分析重油中杂原子化合物的组成及分布。运用Neg ESI FT-ICR MS,研究委内瑞拉奥里常渣减黏裂化反应前后杂原子化合物,建立了分子组成的解析方法。结果表明,常渣中O2类化合物的相对丰度最大,减黏产物中N1类化合物的相对丰度最大。不同缩合度,质荷比小的O2类化合物减黏裂化反应后显著增加。委内瑞拉常渣及其减黏产物中相对丰度最强的O2类化合物均是双环环烷酸。减黏裂化反应使得O2类化合物发生了裂化反应,生成碳数更少、分子质量更小的化合物。
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。