高效液相色谱法测定血液透析器中聚乙烯吡咯烷酮、N,N-二甲基乙酰胺和N-甲基吡咯烷酮溶出量

建立高效液相色谱法测定血液透析器中聚乙烯吡咯烷酮、N,N-二甲基乙酰胺和N-甲基吡咯烷酮三种残留物的溶出量。采用超纯水作为浸提溶剂，模拟临床使用条件，在（37±1）℃的恒温水浴中对样品循环浸提6 h。以乙腈-水（体积比为5∶95）作为流动相等度洗脱，采用高效液相色谱法分离和测定溶出物，检测波长为205 nm。聚乙烯吡咯烷酮、N,N-二甲基乙酰胺和N-甲基吡咯烷酮的质量浓度分别在5.0～100.0、0.2～20.0、0.2～20.0μg/mL范围内与色谱峰面积具有良好的线性关系，相关系数均大于0.999，方法检出限分别为1.461、0.011、0.019μg/mL。样品加标平均回收率为95.13%～103.99%，测定结果的相对标准偏差为0.08%～0.67%(n=6)。该方法制样简单，适用于血液透析器中聚乙烯吡咯烷酮、N,N-二甲基乙酰胺和N-甲基吡咯烷酮三种残留物的溶出量测定。     

微波促进下6,7-二氢-5H-环戊二烯并[4,5]噻吩并[2,3-d]嘧啶-4-胺的简便合成（英文）

微波辐射条件下,以乙醇作溶剂,环戊酮、丙二腈与单质硫反应得到2-氨基-5,6-二氢-4H-环戊二烯[b]噻吩-3-腈(1),1与N,N-二甲基甲酰胺二甲基缩醛在微波辐射条件下反应得到N-(3-氰基-5,6-二氢-4H-环戊二烯[b]-硫基-2-基)-N,N-二甲基亚甲基酰胺(2),进一步在微波辐射条件下由N-(3-氰基-5,6-二氢-4H-环戊二烯[b]-硫基-2-基)-N,N-二甲基亚甲基酰胺(2)与取代芳香胺反应制得目标化合物.合成的25个目标化合物通过熔点测定和核磁共振氢谱分析、红外光谱、高分辨质谱对其结构进行确证.     

含有络合功能基的非天然氨基酸的设计、合成及在生物活性肽中的应用

设计合成了一类侧链带有络合基团的非天然氨基酸, 即侧链带有N,N-二羧甲基氨甲基、N,N-二酰胺甲基氨甲基和N,N-二羟乙基氨甲基的苯丙氨酸衍生物, 并将这类非天然氨基酸用于促性腺激素释放激素(LHRH)类似物的固相合成. 高效液相色谱分析结果表明, 粗肽的纯度较好, 易于纯化; 用电喷雾质谱测定了多肽的分子量. 这些非天然氨基酸可作为其它肽类药物合成的构建单元.     

N－N－二甲基甲酰胺缩二甲醇对喋呤的甲基化反应

用N，N-二甲基甲酰胺缩二甲醇[（CH3）2NCH(OCH3)2，1]和蝶呤（2-氨基-4- 羟基蝶啶）衍生物在极性有机溶剂中反应一般得到脒化产物：N^2-(N，N-二甲基氨 基亚甲基)-蝶呤衍生物，但是在1，4-二氧六环中进行以上反应时发现，N，N-二甲 基酰胺缩二甲醇（1）不仅是脒化试剂，而且也是蝶呤化合物的甲基化试剂，并且 也依据蝶呤的N^2-位的不同取代基进行选择性的N(3)-或O^4-甲基化反应。     

铕-N,N-二(N-亚甲基琥珀酰亚胺)甘氨酸-1,10-二氮杂菲三元配合物的光致变色

合成了N,N-二(N-亚甲基琥珀酰亚胺)甘氨酸,并以元素分析、IR、¹HNMR和质谱进行表征.实验中发现铕(Ⅲ)与N,N-二(N-亚甲基琥珀酰亚胺)甘氨酸和1,10-二氮杂菲形成的配合物具有光致变色的性质.在铕变色物种里,铕离子与N,N-二(N-亚甲基琥珀酰亚胺)甘氨酸中的羧基,1,10-二氮杂菲中的氮原子相结合,同时也可能与水分子和羟基基团结合.     

活性炭固相萃取-气相色谱-质谱法检测人尿中N,N-二甲基乙酰胺和N-甲基乙酰胺

建立了活性炭固相萃取-气相色谱-质谱同时测定尿中N,N-二甲基乙酰胺与N-甲基乙酰胺的气相色谱-质谱测定方法。在pH 7.0条件下,以活性炭固相萃取小柱萃取、净化,以甲醇洗脱,采用Innowax毛细管柱分离,选择离子检测。结果表明,N,N-二甲基乙酰胺和N-甲基乙酰胺线性范围在0.10～40.0 mg/L,相关系数分别为0.9997和0.9995;在空白尿样中分别添加低中高3个浓度水平,N,N-二甲基乙酰胺和N-甲基乙酰胺回收率分别为94.7%～102.6%和96.6%～101.2%,相对标准偏差均小于5.5%;以3倍性噪比计算检出限,N,N-二甲基乙酰胺和N-甲基乙酰胺检出限分别为0.01和0.03 mg/L。本方法精确、稳定、灵敏度高,可用于尿中N,N-二甲基乙酰胺和N-甲基乙酰胺的测定。     

TiO2纳米晶电极上半菁衍生物分子设计中空间位阻效应的研究

设计合成了具有不同空间位阻的吡啶盐类和喹啉盐类半菁染料(E)-N-(4—磺酸 根丙基)-4-[2-4（4-N，N-二乙基氨基苯基）乙烯基]吡啶鎓盐（EPS），（E）-N-(4- 磺酸根丁基）-4-[2-(4-N,N-二乙氨基苯基）乙烯基]吡啶鎓盐（EPS4）和（E） -N-（4-磺酸根丁基）-4-[2-（4-N，N-二乙基氨基苯基）喹啉鎓盐（EQS4），研究了它们 的光物理性质，并将它们用作TiO2纳米晶电极的光敏化剂引入光电化学电池中。 研究发现:对于吡啶类半菁染料而言，无论是以三个亚甲基或是以四个亚甲基来连接 吸附基团RSO3^-和发色团时，单个的EPS和EPS4分子的光电响应行为一致．但是由于 以三个亚甲基来连接时，与EPS4相比，染料EPS的空间位阻相对较小，有利于其在 多孔膜上的吸附，最终结果是染料EPS对TiO2纳米晶电极的敏化作用好于EPS4．以喹啉 环为受电子基团的染料EQS4与同样含有四个亚甲基的以吡啶环为受电 子基团的EPS4相比，单个EQS4分子的光电响应行为虽然好于EPS4分子，但由于 EQS4分子间的空间位阻较大，影响了它在多孔电极上的吸附，致使其敏化的太阳能 电池的总光电转换效率有所下降．     

高效液相色谱-串联质谱法测定食品接触用橡胶奶衬制品中5种化合物的迁移量

建立了食品接触用橡胶奶衬中5种化合物（苯胺、N-甲基苯胺、二苯胍、2-巯基苯并噻唑和苯并噻唑）的高效液相色谱－串联质谱检测方法。采用Agilent Poroshell 120EC－C18（3 mm × 50 mm,2.7 μm）色谱柱进行分离,以0.1%（体积分数）甲酸水溶液和乙腈为流动相梯度洗脱分离,在电喷雾离子源的正离子多反应监测（MRM）模式下检测,外标法定量。结果表明,在优化条件下,5种化合物在对应的质量浓度范围内线性关系良好,相关系数（r2）均不小于0.996 6,检出限（LOD,S/N = 3）和定量下限（LOQ,S/N = 10）分别为0.8～20 μg/L和3～50 μg/L。在3 ~ 500 μg/L加标水平下的平均回收率为93.4% ~ 112%,相对标准偏差（RSD）为0.70% ~ 4.3%。利用该方法检测市售10种奶衬在3个模拟迁移条件（40 ℃ 10 min,40 ℃ 30 min和40 ℃ 120 min）下5种化合物的迁移量,奶衬中5种化合物均有迁出,二苯胍和2-巯基苯并噻唑的迁移量在限量范围内;苯并噻唑的检出需引起关注;苯胺和N-甲基苯胺的迁移量高于其迁移限量（0.01 mg/kg）,有必要改进配方或工艺以控制苯胺和N-甲基苯胺物质的生成。该方法具有操作简单、灵敏度高等优点,可为食品接触用橡胶奶衬制品中5种化合物迁移量的分析提供技术支持。     

氨基酸合成方法研究 V: 相转移催化下N-氰甲基和N-乙氧羰基亚甲基亚氨酸乙酯的Michael加成反应

本文研究了固-液相相转移催化条件下, N-乙氧羰基甲基苯甲亚氨酸乙酯, N-乙氧羰基亚甲基乙亚氨酸乙酯, N-氰甲基苯甲亚氨酸乙酯与丙烯酸酯丙烯腈的Michael加成反应, 以溴化四丁铵为催化剂, K2CO3或KOH为固体碱, 生成α-氨基酸. 本法原料易得,操作简便, 是合成α-氨基酸的一条新路线.     

N-(1,3,2-二氧杂环己烷磷酸酯-2-取代亚甲基)硫代磷酰胺的合成和ESI质谱研究

本文合成了N-(1,3,2-二氧杂环己烷磷酸酯-2-取代亚甲基)硫代磷酰胺，利用核磁共振谱、阳离子ESI质谱和ESI多级质谱鉴定了化合物的结构，对质谱的碎裂规律进行了解释，结果显示ESI多级质谱可以用于N-(1,3,2-二氧杂环己烷磷酸酯-2-取代亚甲基)硫代磷酰胺的结构解析。     

Gas-phase C-H and N-H bond activation by a high valent nitrido-iron dication and NH-transfer to activated olefins

A tetrapodal pentadentate nitrogen ligand (2,6-bis(1,1-di(aminomethyl)ethyl)pyridine, 1) is used for the synthesis of the azido-iron(III) complex [(1)Fe(N3)]X2 where X is either Br or PF6. By means of electrospray ionization mass spectrometry, the dication [(1)Fe(N3)]2+ can be transferred into the gas phase as an intact entity. Upon collisional activation, [(1)Fe(N3)]2+ undergoes an expulsion of molecular nitrogen to afford the dicationic nitrido-iron species [(1)FeN]2+ as an intermediate, which upon further activation can intramolecularly activate C-H- and N-H bonds of the chelating ligand 1 or can transfer an NH unit in bimolecular reactions with activated olefins. The precursor dication [(1)Fe(N3)]2+, the resulting nitrido species [(1)FeN]2+, and its possible isomers are investigated by mass spectrometric experiments, isotopic labeling, and complementary computational studies using density functional theory.     

A Combined Desorption Ionization by Charge Exchange (DICE) and Desorption Electrospray Ionization (DESI) Source for Mass Spectrometry

A source that couples the desorption ionization by charge exchange (DICE) and desorption electrospray ionization (DESI) techniques together was demonstrated to broaden the range of compounds that can be analyzed in a single mass spectrometric experiment under ambient conditions. A tee union was used to mix the spray reagents into a partially immiscible blend before this mixture was passed through a conventional electrospray (ES) probe capillary. Using this technique, compounds that are ionized more efficiently by the DICE method and those that are ionized better with the DESI procedure could be analyzed simultaneously. For example, hydroquinone, which is not detected when subjected to DESI-MS in the positive-ion generation mode, or the sodium adduct of guaifenesin, which is not detected when examined by DICE-MS, could both be detected in one experiment when the two techniques were combined. The combined technique was able to generate the molecular ion, proton and metal adduct from the same compound. When coupled to a tandem mass spectrometer, the combined source enabled the generation of product ion spectra from the molecular ion and the [M + H]⁺ or [M + metal]⁺ ions of the same compound without the need to physically change the source from DICE to DESI. The ability to record CID spectra of both the molecular ion and adduct ions in a single mass spectrometric experiment adds a new dimension to the array of mass spectrometric methods available for structural studies.     

Sensitivity of redox reactions of dyes to variations of conditions created in mass spectrometric experiments

Redox behaviour of four imidazophenazine dye derivatives under mass spectrometric conditions of matrix-assisted laser desorption/ionization (MALDI), laser desorption/ionization (LDI) from metal and graphite surface, electrospray, low temperature secondary ion mass spectrometry (LT SIMS) and fast atom bombardment (FAB) was studied and distinctions in the reduction-dependent spectral patterns were analyzed from the point of view of different quantities of protons and electrons available for reduction in different techniques. The reduction products [M + 2H](+*), [M + 3H](+) and M(-*), [M + H](-) were observed in the positive and negative ion modes, respectively, which permitted to suggest independent occurrence of reduction and protonation/deprotonation processes. LDI from graphite substrate was the only technique that allowed us to obtain abundant negative ions of all dye derivatives. The yield of field ionization (FI) or field desorption (FD) mechanism to ion formation under LDI from rough graphite surface has been addressed. The sensitivity of reduction of the dyes to variation of reduction-initiating agents confirms high redox activity of the dyes essential for their functioning in natural and artificial systems.     

Structural determination of picomole amounts of phospholipids via electrospray ionization tandem mass spectrometry

The remarkable sensitivity of electrospray ionization was exploited to achieve great increases in the sensitivity of tandem mass spectrometric analyses of phospholipids derived from both synthetic and biologic sources. Herein, we demonstrate that (1) product-ion spectra after electrospray ionization can be obtained easily by utilizing ≤ 5 pmol of phospholipid with a mass-selected window of less than 2 mass units, (2) the low energy inherent in the electrospray ionization method facilitates analysis of labile molecular ions that are not easily detected with the relatively high energy employed during fast-atom bombardment desorption, and (3) collision-induced dissociation of precursor ions generated from electrospray ionization often resulted in novel product-ion patterns. Collectively, these results underscore the utility of electrospray ionization tandem mass spectroscopy for the structural determination of diminutive amounts of phospholipids.     

Tandem mass spectrometric analysis of distinct fragmentation patterns to [M+Na]/z and [M+H]/z of dendritic Al(III) and Zn(II) quinolates

The synthesis of two novel dendritic aluminum and zinc quinolates, which are soluble in common solvents, was monitored effectively by positive ion electrospray ionization mass spectrometry (ESI-MS). Through tandem mass spectrometric analysis of the complexes, distinct fragmentation pathways for sodium adduct molecular ion [M+Na]+ and protonated molecular ion [M+H]+ were observed.     

Decomposition of protein nitrosothiolsin matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometry

The S-nitrosylation of proteins is involved in the trafficking of nitric oxide (NO) in intra- and extracellular milieus. To establish a mass spectrometric method for identifying this post-translational modification of proteins, a synthetic peptide and transthyretin were S-nitrosylated in vitro and analyzed by electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The intact molecular ion species of nitrosylated compounds was identified in the ESI mass spectrum without elimination of the NO group. However, the labile nature of the S-NO bond was evident when the in-source fragmentation efficiently generated [M + H - 30](+) ions. The decomposition was prominent for multiply charged transthyretin ions with high charge states under ordinary ESI conditions, indicating that the application of minimum nozzle potentials was essential for delineating the stoichiometry of nitrosylation in proteins. With MALDI, the S-NO bond cleavage occurred during the ionization process, and the subsequent reduction generated [M + H - 29](+) ions.     

Characterization and determination of six aristolochic acids and three aristololactams in medicinal plants and their preparations by high-performance liquid chromatography-photodiode array detection/electrospray ionization mass spectrometry

Aristolochic acid derivatives (AAs) and aristolactam derivatives (ALs) have been characterized by electrospray ionization mass spectrometry, and their fragmentation pathways are proposed. ALs exhibit a single ionization product [M+H]+, whereas AAs show multiple ionization products. By optimizing the chromatographic separation and mass spectrometric parameters, the precursor ions of the derivatives with the best responses were found, and the sensitivities in the determination of the nine derivatives were improved. Based on the investigation of ionization behaviour, a HPLC-DAD/ESI-MS (high-performance liquid chromatography-photodiode array detection/electrospray ionization mass spectrometry) method has been developed for simultaneous analysis of nine derivatives, i.e., AA I, AA II, AA C, AA D, 7-OH AA I, aristolic acid I, AL AII, AL IIIa and AL IVa, in nine medicinal herbs and two preparations. The method appears to be suitable for safety assurance and quality control of commercially available samples with good selectivity and suitable sensitivity.     

Microgradient separation technique for purification and fractionation of permethylated N‐glycans before mass spectrometric analyses

Analysis of N‐glycans released enzymatically from patients’ sera or other clinical samples may provide diagnostically and prognostically important information on human disease. Permethylation of these biomolecules simultaneously increases their hydrophobicity and substantially improves their detection parameters in the following mass spectrometric analyses. The overall procedure, from the glycan cleavage to the final mass spectrometric determinations, includes several steps involving extraction, derivatization, and purification. During these steps, certain polymeric contaminants that may have been coincidentally introduced could hamper the final measurements. To understand and counter these interferences and further fractionate or preconcentrate these glycans, we introduce here an effective microgradient chromatographic technique that employs a small reversed‐phase microcolumn connected to a gas‐tight microsyringe delivering a mobile‐phase gradient. After loading the glycan fraction onto the microcolumn, three elution steps are recommended: (1) remove polar contaminants; (2) recover permethylated glycans for either liquid chromatography with electrospray ionization mass spectrometry or matrix‐assisted laser desorption/ionization mass spectrometry; and (3) remove larger polymeric contaminants and regenerate the precolumn. We further demonstrate that the trapped second fraction can be beneficially preconcentrated and further separated to achieve matrix‐assisted laser desorption/ionization mass spectrometric detection of the derivatized N‐glycans up to 6300 Da. The enhanced detection capabilities for tetra‐antennary N‐glycans are of increasing interest in disease biomarker discovery.     

Matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometric study of 2,3-dihydro-1,4-benzoxazepines

Fragmentations of the protonated adduct ions [M+H](+) of seven 1,4-benzoxazepine derivatives were studied using 'post-source decay' matrix-assisted laser desorption/ionization (PSD MALDI) and electrospray nozzle-skimmer collisionally induced dissociation (ESI-CID) mass spectrometric methods. It was found that both methods generated mainly product ions arising from the cross-ring cleavages of the benzoxazepine ring. Similar product ions were generated under MALDI and ESI conditions; however, it was observed that the loss of the alkylene unit from the N-substituted benzoxazepine, and the loss of a H(2)X molecule (where X = O or S), are more preferred under ESI conditions. Based on the experimental results a mechanism is also proposed for the fragmentation of the oxazepines studied.     

Electrospray ionization mass spectrometric analysis of highly reactive glycosyl halides

Highly reactive glycosyl chlorides and bromides have been analysed by a routine mass spectrometric method using electrospray ionization and lithium salt adduct-forming agents in anhydrous acetonitrile solution, providing salient lithiated molecular ions [M+Li]?, [2M+Li]? etc. The role of other adduct-forming salts has also been evaluated. The lithium salt method is useful for accurate mass determination of these highly sensitive compounds.