锂分子的TIMS探测

After the determination for lithium isotope abundant was accomplished, the electrical current on the ionization and vaporization strip is increased and the big current of lithium ion is kept. The ionic current of Li2 is inspected by magnetic field scanning and the ionic current of Li₂ is reality, but ¹²Li₂^＋、¹³Li₂^＋、14Li₂^＋ are not separated and they compose the widest peak form.     

联苯-取代哌嗪衍生物的质谱研究

合成了三类取代哌嗪修饰的新型联苯哌嗪化合物,并对这些化合物进行多级电喷雾 离子阱质谱裂解分析。在一级全扫描质谱中发现,三乙胺与4,4′-二甲氧基-5,6,5′,6′-二次甲二氧基联苯-2-甲酸酯-2′-甲酰基-4-取代哌嗪化合物形成[M+101+H]⁺。实验还发现,结构中有氟原子存在的联苯-2-甲酸酯-2′-甲酰基-4-取代哌嗪化合物更易与钠离子结合形成加钠的准分子离子[M+Na]⁺。二级质谱说明,4,4′-二甲氧基-5,6,5′,6′-二次甲二氧基联苯-2-甲酸酯-2′-甲酰基-4-取代哌嗪化合物的哌嗪上取代基的不同,对二级质谱的碎片离子形式有显著的影响。     

LC-MS/MS法测定大鼠血浆中MTP-131

MTP-131 is a tetrapeptide under development for treating diabetes. MTP-131 contains a lysine, an arginine, a phenylalanine and a modified tyrosine in its structure. The quantification of MTP-131 in rat plasma was developed and validated by liquid chromatography-tandem mass spectrometry(LC-MS/MS). MTP-131 was separated from plasma by Waters Oasis^® HLB cartridge solid phase extraction, then separated by C₁₈ column. The mobile phase consisted of V(acetonitrile):V(10 mmol L^－1 ammonium acetate):V(acetic acid)＝30:70:0.04. A mass spectrometer equipped with electrospray ionization source was used as a detector and operated in the positive ion mode. Selected reaction monitoring(SRM) using the double protonated molecules of [M＋2H]^2＋ for MTP-131, three main fragment ions of m/z 70, 84, 20 were used for the quantification. The d5-MTP-131 was used as the internal standard. The method exhibites a linear range of 1.0-10 000μg L^－1 for MTP-131 with a lower limit of quantification at 1.0 μg L^－1. The intra- and inter-assay precisions are below 9.9%, and relative errors within 6.0%. The mean extraction recovery of MTP-131 is above 80%. Under the selected chromatographic conditions and sample preparation conditions, there is no significant matrix effect of MTP-131 at low or high concentrations. The validated method proves to be sensitive, rapid, and is applied successfully for the pharmacokinetic study of MTP-131 in rat.     

沃尼妙林在电喷雾质谱中的行为研究

采用电喷雾质谱研究沃尼妙林在正负离子模式下电离的碎裂行为。在正离子模式下进行一级质谱全扫描时,主要得到[M+H]⁺ m/z 565.7的分子离子峰,负离子模式主要得到[M-H]-m/z 563.5的分子离子峰,正离子的响应值远高于负离子。以[M+H]+为母离子进行二级质谱扫描,在适当的碰撞能下,主要得到 m/z 263.2、285.3、303.3三个碎片离子峰,其中 m/z 263.2的丰度明显高于另外2个碎片离子。并分析了沃尼妙林的碎裂机理,为进一步研究其构效关系、药物分析及残留检测等提供依据。     

水飞蓟宾的负离子电喷雾离子阱质谱研究

采用电喷雾离子阱（ESI-MS）质谱技术对水飞蓟宾的结构和裂解途径进行研究。采用ESI-MS获得了 m/z 481[M-H]^-,采用ESI-MS²获得了 m/z 453、m/z 301等碎片离子。发现ESI-MS²质谱生成A环和B环C—O—C键断裂的碎片,并对 m/z 453、m/z 301特征碎片离子进行ESI-MS³质谱研究,归属了其主要特征碎片离子,分析和讨论了该化合物的结构和质谱特征。     

HPLC-MS/MS法快速测定淀粉生物粘附材料特异性结合糖类物质的含量

研究了高效液相色谱-串联质谱(HPLC-MS/MS)法测定淀粉生物粘附材料与糖残基特异性结合实验中,岩藻糖、半乳糖、α-甲基甘露糖苷和N-乙酰葡萄糖胺4种糖类物质含量的分析方法。将反应后的样品直接离心过滤后即可利用HPLC-MS/MS进行定性定量分析。以V(乙腈)∶V(水)=80∶20的溶液作为液相色谱流动相,质谱采用电喷雾负离子电离方式扫描,以多反应监测(MRM)模式进行定量分析。在添加水平为1.0~40.0 mg.L-1范围内,岩藻糖的回收率为111.0%,相对标准偏差(RSD)为6.55%;在添加水平为1.0~80.0 mg.L-1范围内,半乳糖、α-甲基甘露糖苷和N-乙酰葡萄糖胺的回收率分别为106.5%、99.0%和91.0%,相对标准偏差分别为7.78%、6.64%和5.68%。4种糖类物质的方法检出限(S/N≥3)分别为0.1mg.L-1(岩藻糖),1.0 mg.L-1(半乳糖),0.1 mg.L-1(α-甲基甘露糖苷)和0.5 mg.L-1(N-乙酰葡萄糖胺)。该方法可用于评价淀粉粘附材料和糖类物质的特异性结合,为其他领域中糖类物质含量的测定提供可借鉴的方法。     

高效液相色谱-串联质谱法测定鸡蛋中三聚氰胺残留

An high-performance liquid chromatographic method with tandem mass spectrometry(HPLC-MS/MS) was developed for the determination of melamine residues in egg. In the method, the melamine residue was extracted with V(1% Trichloroacetic acid):V(methanol)＝1:1, cleaned-up with PCX solid phase extraction column, and concentrated to dry under nitrogen and redissolved in 1 mL dissolving solution. The solution was separated on a RP-HPLC column, and detected by HPLC-MS/MS with positive electrospray ionization(ESI＋) in multiple reaction monitoring(MRM) mode. Quantitation was carried out using an external standard method. The standard curves for all compounds are linear over the concentration range of 20-400 μg kg^－1 with correlation coefficients(r2) of 0.998 5. The recoveries of melamine from egg samples spiked with the concentration levels at 50, 100, 200 μg kg^－1 are range of 87.0%, 96.8%, 94.4%. The limits of detection for the method are 3 μg kg^－1. The limits of quantification for the method are 10 μg kg^－1. The results show that the established method is of simplicity, rapidity, high sensitivity, good reproducibility and better selectivity. The method is quite fit for identification and determination of melamine in egg.     

多接收电感耦合等离子体质谱法测量UTB系列铀同位素工作标准同位素比值

In order to analyze uranium isotopic ratios accurately by mass spectrometry, reference materials are used to correct the mass bias and detector bias. Isotopic ratios of UTB U Series working reference material which have been developed in our country last century were measured by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). In this report, the isotopic ratios were corrected by measuring CRM U series reference material. Hydride rate UH^＋/U⁺ of different sample introduction devices were studied. The linearity of the Daly detector was also investigated. Preliminary results have indicated that there is no significant difference between the measurement value and reference value.     

表面解吸常压化学电离质谱法直接测定饮料中的抗坏血酸

建立了表面解吸常压化学电离质谱(SDAPCI-MS)测定饮料中抗坏血酸的方法。采用进样针取样,每次取样不多于5 nL,无需任何样品预处理,单个样品测定时间少于0.5 min。该方法对抗坏血酸的检出限可达1.9×10-9g.mL-1,线性范围为10-8~10-3g.mL-1,回收率为89.9%~109.6%,相对标准偏差(RSD)为3.2%~5.8%。     

Development of Technology and Method for Phosphoproteome and Glycoproteome Analysis

The elucidation of protein post-translational modifications, such as phosphorylation, remains a challenging analytical task for proteomic studies. Since many of the proteins targeted for phosphorylation are low in abundance and phosphorylation is typically substoichiometric, a prerequisite for their identification is the specific enrichment of phosphopeptide prior to mass spectrometric analysis. A new type of the immobilized metal ion affinity chromatography (IMAC) through the chelating interaction between phosphate groups on the polymer and Zr^4＋ and Ti^4＋ (Zr^4＋- and Ti^4＋-IMAC) has been developed for enriching phosphopeptides. We also compared Zr^4＋- and Ti^4＋-IMAC to other enrichment methods including Fe^3＋-IMAC, TiO₂ and ZrO₂, and demonstrate superior selectivity and efficiency of Zr^4＋- and Ti^4＋-IMAC for the isolation and enrichment of phosphopeptides. Furthermore, a new approach was established by integration of the enrichment of phosphopeptides with Ti^4＋-IMAC and peptide fractionation with strong cation-exchange (SCX) column for large-scale phosphoproteome analysis of human liver, and about 10 000 phosphorylation sites were detected. Compared with large scale phosphorylation analysis at proteome level, comprehensive and reliable phosphorylation site mapping of individual phosphoprotein is equally important. A novel method for confident phosphorylation site analysis of individual phosphoproteins was developed without manual interpretation of spectra. Phosphopeptides enriched from tryptic digests of phosphoproteins were analyzed by nano-LC-MS²/MS³, and the acquired MS² and MS³ spectra in valid MS²/MS³ pairs were searched against the composite database separately. This methodology combined with multi-protease digestion approach was applied to analyze the phosphorylation of the standards phosphoproteins and cyclic AMP dependent protein kinases. In silico digestion of proteins in human proteome database by trypsin indicates that a significant percentage of tryptic N-glycopeptides is not in the preferred detection mass range of shotgun proteomics approach, that is, from 800 to 3 500 Da. And the quite big size of glycan groups may block trypsin to access the K, R residues near N-glycosites for digestion, which will result in generation of big glycopeptides. Thus many N-glycosites could not be localized if only trypsin was used to digest proteins. We developed a comprehensive way to analyze the N-glycoproteome of human liver tissue by combination of hydrazide chemistry method and multiple enzyme digestion, which leads to great improvement in coverage of N-glycosites identified.相似文献