高效液相色谱法测定CO2膨胀前后烟丝中氨基酸

本文研究了用Waters柱前衍生试剂AQC,即6-氨基喹啉基-N-羟基琥珀酰亚氨基酸甲酸来测定CO2膨胀前后烟丝中的氨基酸的组成和含量,流动相由磷酸盐缓冲液、乙腈和纯水构成,梯度洗脱。结果表明:烟丝在CO2膨胀前后样品所测16种游离氨基酸的总量普遍减少。     

9,9-二(丙酸二甲氨基乙酯)芴共聚物的合成及荧光性能

采用迈克尔加成反应制备了单体2,7-二溴-9,9-二(丙酸二甲氨基乙酯)芴(FDMAEA);采用Suzuki偶合反应制备了不同FDMAEA结构单元含量的醇溶性9,9-二(丙酸二甲氨基乙酯)芴-9,9-二辛基芴共聚物(PFDMAEA)。通过核磁共振、凝胶渗透色谱、溶解性测试、紫外-可见光光谱、荧光发射光谱等对其进行了分析研究。结果表明,成功合成了2,7-二溴-9,9-二(丙酸二甲氨基乙酯)芴及9,9-二(丙酸二甲氨基乙酯)芴-9,9-二辛基芴共聚物。该共聚物在极性溶剂,如甲醇中具有良好的溶解性。由于含有DMAEA支链的PFDMAEA主链容易扭曲,共轭长度变短,共聚物的紫外吸收光谱和荧光光谱随着FDMAEA含量的增加而发生蓝移。荧光发光光谱研究表明,溶剂的极性、溶液的浓度、温度和pH值对共聚物的发光性能有很大的影响。随着溶剂极性增大,共聚物的荧光发射强度不断增加。荧光发射强度随溶液浓度的增加先增加后降低,随着溶液温度的上升而降低。当溶液pH值由1增大到14时,荧光强度不断降低,直至淬灭。     

共轭性芳杂环聚甲亚胺的合成及性能研究

以乙二醛分别与2,6-二氨基吡啶、2,6-二(对氨基苯)苯并[1,2-d;5,4-d']二噁唑、2,5-二(4'-氨基苯基)-1,3,4-噁二唑、N-乙基-3,6-二氨咔唑缩聚合成了4种新型的共轭性芳杂环聚甲亚胺.采用Uv-vis、IR和1HNMR方法对聚合物的结构进行了表征,并对其热稳定性、导电性及荧光性能进行了研究.结果表明,该类共轭性芳杂环聚甲亚胺具有良好的热稳定性,其热降解温度均在370℃以上.共轭性芳杂环聚甲亚胺具有很好的荧光性,掺杂后荧光性明显增强,电导率从10-10～10-12S/cm增加到10-5～10-6S/cm,达到了半导体水平.     

纳米粒子改性二苯乙烯型荧光增白剂的制备及性能研究

以4,4’-二氨基二苯乙烯-2,2’-二磺酸(简称DSD酸)为荧光母体,利用三聚氯氰的交联反应,经过亲核取代将乙醇胺、3-氨基丙基三甲氧基硅烷(KH-540)与荧光母体连接起来,制备了一种荧光增白剂。然后将其作为原料,采用改进的stober水解法,制备出了含有二苯乙烯型荧光增白剂的SiO2荧光纳米复合粒子。利用红外光谱仪测定了其结构,用扫描电镜(SEM)、透射电镜(TEM)、纳米粒度分析仪、热重(TG)分别对其形貌和热稳定性进行了观察,用紫外-可见光谱、荧光光谱对产物的光物理化学进行了表征,并利用紫外老化实验考察了荧光纳米粒子对纸张的返黄抑制效果。结果表明,在使用性能上,相同量的荧光增白剂,用纳米粒子改性后其对纸张的增白效果及光抑制效果更好。     

小肽BCEOC衍生物的非水毛细管电泳分离研究

以1,2-苯并-3,4二氢咔唑-9-乙基氯甲酸酯(BCEOC)作为柱前衍生试剂,采用非水毛细管电泳对衍生小肽进行分离。在甲醇乙腈混合液为溶剂,乙酸-乙酸铵为缓冲体系,20℃,28kV,235nm二极管阵列检测(DAD)条件下,采用非水毛细管电泳模式,考察并优化小肽衍生物的分离条件,实现四种小肽衍生物的基线分离。     

填充色谱柱法测定4-氨基二苯胺的纯度

采用填充色谱柱的方法来分析4-氨基二苯胺。文中就色谱固定相的配制、色谱分离柱的制备以及分析操作条件进行了详细的阐述,并据此建立了4-氨基二苯胺的纯度的分析方法。对试剂级的4-氨基二苯胺的分析结果表明该方法快速准确,能较好地满足生产的需要。     

液相荧光法检测乳制品中9种氨基糖苷类药物残留

本文建立了高效液相色谱荧光检测乳制品中的9种氨基糖苷类药物残留方法.样品用10%三氯乙酸提取,采用MCX固相萃取小柱净化,C(18)色谱分离,流动相采用乙腈:庚烷磺酸钠缓冲溶液梯度淋洗,柱后用次氯酸钠溶液氧化,邻苯二醛(OPA)衍生,荧光检测.9种氨基糖苷类药物加标回收率在69.8%-110.2%之间,方法的定量限为0...     

含烷基噻吩与三嗪π-共轭聚合物的合成及性能

以二价镍配合物(Ni(dppp)Cl2)作为催化剂,2-二异丙基氨基-4,6-二氯均三嗪分别与3-丁基-2,5-二溴噻吩格氏(Grignard)试剂、3-辛基2,5-二溴噻吩格氏试剂、3-十二烷基-2,5-二溴噻吩格氏试剂交替共聚合成了3种含2-二异丙基氨基均三嗪的聚合物P1,P2和P3。并经傅里叶变换红外光谱、氢核磁共振谱、紫外-可见光谱、荧光光谱、循环伏安、X射线粉末衍射和凝胶渗透色谱等测试手段对其进行了表征,对聚合物P1在CHCl3溶液中的酸致变色行为进行了研究。结果表明,得到的聚合物在甲苯、氯仿、四氢呋喃(THF)等有机溶剂中溶解性好,3种聚合物的紫外-可见最大吸收波长在372 nm处出现,在CHCl3溶液中聚合物P1,P2,P3最大发射峰分别位于478 nm,549 nm和523 nm。聚合物均在-1.8~0 V出现n-掺杂峰。通过X射线衍射测试聚合物均有一定结晶性但结晶性较差。     

用飞秒Ti：sapphire激光测定对称型化合物的双光子吸收和上转换荧光

用800nm波长的飞秒Ti:sapphire激光测定了2个对称型噁二唑衍生物2,5-二[4-(2-N,N-二苯氨基苯乙烯基)苯基]-1,3,4-噁二唑(PASPO)与2,5-二[4-{2-N,N-二(4-溴代苯)氨基苯乙烯基]苯基}-1,3,4-噁二唑(BrPASPO)的双光子吸收和双光子激发荧光光谱,其飞秒双光子吸收截面为20.6和9.91GM,双光子泵浦上转换荧光最大波长分别在535和545nm.测定了紫外吸收、荧光光谱,研究了化合物在不同溶剂中的溶致变色效应.化合物PASPO和Br-PASPO在二氯甲烷溶液中的吸收峰分别位于412和403nm,荧光发射峰分别位于511和495nm,荧光量子产率分别为0.73和0.70.     

丝素改性胶原膜的肝素化及其体外抗凝血性能评价

以1-(3-二甲氨基丙基)-3-乙基碳二亚胺(简称EDCI)为缩合剂对丝素改性胶原膜进行了肝素固定化,测定并研究了固定化肝素的稳定性,应用X光电子能谱分析了材料的表面性质。以凝血酶原时间(PT)、部分凝血活酶时间(APTT)、凝血酶时间(TT)等3个体外凝血时间为评价标准,考察了材料的抗凝血性能。结果表明,肝素化后的丝素改性胶原膜具有良好的抗凝血性。     

Determination of trace c(1)-c(4) aliphatic alcohols in aqueous samples by 9-fluorenylmethyl chloroformate derivatization and reversed-phase high-performance liquid chromatography

A simple procedure for precolumn fluorescence derivatization of low-molecular-weight aliphatic alcohols (C(1)-C(4)) with 9-fluorenylmethyl chloroformate is presented. The derivatization reaction proceeds in 1:1 (v/v) aqueous-acetonitrile solution at room temperature with a sodium phosphate buffer of pH 12.5 as a catalyst. Stable fluorescent derivatives of the alcohols are formed within 10 min. The four derivatives are separated by reversed-phase high-performance liquid chromatography and detected by a fluorescence detector at an excitation wavelength of 259 nm and an emission wavelength of 311 nm. The method detection limits are 4, 40, 70, and 30 pmol for methanol, ethanol, propanol, and butanol, respectively, per 5-μL injection volume. The relative standard deviations are 3.7% for methanol at 75 pmol and 2.1, 1.5, and 2.2% for ethanol, propanol, and butanol, respectively, at 750 pmol. As a preliminary application, the method was used to determine methanol concentration in laboratory air and ethanol content in a commercial alcoholic beverage.     

Trace Determination of Glycols by HPLC with UV and Electrospray Ionization Mass Spectrometric Detections

A high-performance liquid chromatography/mass spectrometry (HPLC/MS) method is developed for trace determination of glycols (ethylene glycol, 1,2- and 1,3-propylene glycols, and 2,3-butylene glycol) in water after derivatization with benzoyl chloride. Benzoyl esters of glycols are separated by microcolumn reversed-phase HPLC. Sensitivity and linearity of UV detection at 237 nm is compared with electrospray ionization mass spectrometric (ESI-MS) detection using selected ion monitoring. Limits of detection (LOD) and quantitation (LOQ) for UV detection are 1 and 2 mg/L, respectively. For ESI-MS detection, LOD and LOQ are in the ranges 10-25 and 20-50 μg/L, respectively. LOD obtained by ESI-MS for the determination of glycols is improved by 2-3 orders of magnitude in comparison to previously published methods. The effect of the structure of isomeric glycols on their electrospray mass spectra is discussed. The method has been applied for the determination of glycols in aqueous matrixes containing high concentrations of salts occurring in nuclear waste disposal treatment.     

Screening and identification of acidic carbohydrates in bovine colostrum by using ion/molecule reactions and Fourier transform ion cyclotron resonance mass spectrometry: specificity toward phosphorylated complexes

A screening method was developed for the identification of acidic saccharides from biological mixtures utilizing gas-phase derivatization and mass spectrometry. Phosphorylated compounds were differentiated from other acidic species by exploiting the selective reactivity of chlorotrimethylsilane with the phosphate ions (phosphorylated compounds shift by 72 Da, allowing rapid compound detection). A 13-component mock mixture was used to demonstrate the viability of the method, and a detection limit of 600 nM (30 fmol) was determined. This method was applied to the identification of acidic compounds from bovine colostrum. To further verify the selectivity of the ion/molecule reaction, exact mass measurements were used to determine the elemental composition of 14 compounds. Eight novel acidic carbohydrate species were observed in bovine colostrum, six of which have never been reported previously in milks. Tandem mass spectrometric experiments allowed compound characterization for two of these components.     

Combining fluorescence detection and mass spectrometric analysis for comprehensive and quantitative analysis of redox-sensitive cysteines in native membrane proteins

Monobromobimane (MBB) is a lipophilic reagent that selectively modifies free cysteine residues in proteins. Because of its lipophilic character, MBB is capable of labeling cysteine residues in membrane proteins under native conditions. Reaction of MBB with the sulfhydryl groups of free cysteines leads to formation of highly fluorescent derivatives. Here we describe a procedure for the detection and relative quantitation of MBB-labeled cysteines using fluorescence and mass spectrometric analyses, which allow determination of free cysteine content and unambiguous identification of MBB-modified cysteine residues. We have applied this approach to the analysis of the free and redox-sensitive cysteine residues of a large membrane protein, the sarcoplasmic reticulum Ca2+ release channel with a molecular mass of 2.2 million Da. Labeling was performed under physiologic conditions where the channel complex is in its native environment and is functionally active. The purified MBB-labeled channel complex was enzymatically digested, and the resulting peptides were separated by reversed-phase high-performance chromatography. MBB-labeled peptides were detected by fluorescence and identified by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Under MALDI conditions, partial photolytic fragmentation of the MBB-peptide bound occurred, thus allowing convenient screening for the MBB-modified peptides in the MS spectrum by detection of the specific mass increment of 190.07 Da for MBB-modified cysteine residues. Modification of the peptides was further confirmed by tandem mass spectrometric analysis, utilizing sequencing information and the presence of the specific immonium ion for the MBB-modified cysteine residues at m/z 266.6. Quantitative information was obtained by comparison of both fluorescence and MS signal intensities of MBB-modified peptides. Combination of fluorescence with MS detection and analysis of MBB-labeled peptides supported by a customized software program provides a convenient method for identifying and quantifying redox-sensitive cysteines in membrane proteins of native biological systems. Identification of one redox-sensitive cysteine (2327) in the native membrane-bound sarcoplasmic reticulum Ca2+ release channel is described.     

Ion-molecule reactions for the characterization of polyols and polyol mixtures by ESI/FT-ICR mass spectrometry

A mass spectrometric method is described for the identification and counting of hydroxyl groups in an analyte. Analytes introduced into a FT-ICR mass spectrometer and ionized by positive mode ESI were allowed to react with the neutral reagent diethylmethoxyborane. This results in derivatization of the hydroxyl groups of the analytes by replacement of a proton with a diethylborenium ion. Protonated polyols react by consecutive derivatization reactions, wherein all, or nearly all, of the hydroxyls are derivatized. The polyol derivatization products are separated by 68 mass units in the mass spectrum. This 68 Da mass shift, along with 30 Da mass shifts arising from intramolecular derivatization of the primary derivatization products, makes it easy to count the number of functional groups present in the analyte. The utility of this method for the analysis of polyols as single-component solutions, as mixtures, or in HPLC effluent (LC-MS analysis) is demonstrated.     

凝胶色谱净化-气相色谱串联质谱法测定猪肉中16种有机氯类农药残留

建立了凝胶色谱(GPC)净化、气相色谱-串联质谱(GC-MS/MS)同时测定猪肉中16种有机氯类农药残留的方法。样品中的待测农药组分经丙酮、正己烷提取、GPC净化去除油脂等杂质,GC-MS/MS采用多反应监测模式(MRM)采集数据后进行定性/定量分析。待测农药的加标回收率在82%～106%之间,方法的相对标准偏差(RSD)≤10.9%,各农药组分的检出限为0.1～0.9μg/kg。     

Monolithic column HPLC separation of intact proteins analyzed by LC-MALDI using on-plate digestion: An approach to integrate protein separation and identification

A method is developed to integrate a protein separation by monolithic capillary reversed-phase high-performance liquid chromatography to on-probe tryptic digestion for subsequent analyses by MALDI-TOF MS and MALDI-TOF/TOF MS. The method provides a means of directly interfacing separations to MALDI-MS, reducing the amount of time required for traditional procedures involving in-solution enzymatic digestion and sample cleanup prior to MALDI-MS analysis. When used with pI-based fractionation as a first dimension, it provides a means of analyzing complex mixtures of proteins with minimal sample handling and cleanup. The use of monolithic capillary columns sufficiently resolved intact proteins so that peptide mass fingerprinting analysis by MALDI-TOF MS resulted in the identification of close to 40 unique proteins from 120 ng of sample obtained from a prefractionated MCF10 cell line at pH 6.34, where the identifications of several of these proteins were also confirmed by intact MW and tandem mass spectrometric analysis. The reproducibility of this method has been demonstrated to be sufficient for the purpose of protein identifications. Experimental values of protein intact MW are obtained and compared to that expected for each protein identified.     

衍生化-液相色谱-紫外检测联用测定尿中γ-羟基丁酸

本文建立了尿中γ-羟基丁酸的水相催化衍生化-液相色谱-紫外检测联用分析方法。尿样中直接加入衍生化试剂α-溴苯乙酮、催化剂四丁基溴化铵,在80℃水浴中加热30 min,衍生化产物直接进行液相色谱-紫外检测。尿中γ-羟基丁酸浓度在0.5μg/mL-250μg/mL之间具有良好的线性关系,最低检出限为0.20μg/mL。该方法具有较好的灵敏度、准确性和精密度,能够满足司法鉴定工作的要求,具有一定的实用性。     

Characterization of protein phosphorylation by mass spectrometry using immobilized metal ion affinity chromatography with on-resin beta-elimination and Michael addition

A protocol combining immobilized metal ion affinity chromatography and beta-elimination with concurrent Michael addition has been developed for enhanced analysis of protein phosphorylation. Immobilized metal ion affinity chromatography was initially used to enrich for phosphorylated peptides. Beta-elimination, with or without concurrent Michael addition, was then subsequently used to simultaneously elute and derivatize phosphopeptides bound to the chromatography resin. Derivatization of the phosphate facilitated the precise determination of phosphorylation sites by MALDI-PSD/LIFT tandem mass spectrometry, avoiding complications due to ion suppression and phosphate lability in mass spectrometric analysis of phosphopeptides. Complementary use of immobilized metal ion affinity chromatography and beta-elimination with concurrent Michael addition in this manner circumvented several inherent disadvantages of the individual methods. In particular, (i) the protocol discriminated O-linked glycosylated peptides from phosphopeptides prior to beta-elimination/Michael addition and (ii) the elution of peptides from the chromatography resin as derivatized phosphopeptides distinguished them from unphosphorylated species that were also retained. The chemical derivatization of phosphopeptides greatly increased the information obtained during peptide sequencing by mass spectrometry. The combined protocol enabled the detection and sequencing of phosphopeptides from protein digests at low femtomole concentrations of initial sample and was employed to identify novel phosphorylation sites on the cell adhesion protein p120 catenin and the glycoprotein fetuin.     

Electrogenerated chemiluminescence derivatization reagents for carboxylic acids and amines in high-performance liquid chromatography using tris(2,2'-bipyridine)ruthenium(II)

2-(2-Aminoethyl)-1-methylpyrrolidine and N-(3-aminopropyl)pyrrolidine (NAPP) were found to be selective and sensitive derivatization reagents for carboxylic acid by high-performance liquid chromatography (HPLC) with electrogenerated chemiluminescence detection using tris(2,2'-bipyridine)ruthenium(II). Free fatty acids and ibuprofen were used as model compounds of carboxylic acids, and the derivatization conditions were optimized with myristic acid as a representative of free fatty acids. All the fatty acids tested were reacted with NAPP to produce highly sensitive derivatives under the mild reaction conditions of room temperature for 30 min in acetonitrile containing 2-bromo-1-ethylpyridinium tetrafluoroborate and 9-methyl-3,4-dihydro-2H-pyrido[1,2-a]pyrimidin-2-one. The chemiluminescence intensities were similar for all fatty acids. The derivatives obtained from 10 free fatty acids were completely separated by reversed-phase chromatography under isocratic elution conditions. The on-column detection limits (signal-to-noise ratio of 3) with proposed HPLC separation and chemiluminescence detection were 70 and 45 fmol for myristic acid and ibuprofen, respectively. The free fatty acids in human plasma were successfully determined using the present method. Histamine, a model compound of primary amines, was also determined after precolumn derivatization with 3-(diethylamino)propionic acid at room temperature for 60 min in acetonitrile containing N,N'-dicyclohexylcarbodiimide and 3,4-dihydro-3-hydroxy-4-oxo-1,2,3-benzotriazine with the detection limit of 70 fmol.