顶空-气相色谱-质谱联用分析桂花和叶中挥发性成分

采用谱库检索结合准确质量测定、保留指数、串联质谱技术的多维定性分析策略鉴定化合物, 能够提高定性分析的效率和准确性. 运用顶空-气相色谱-四极质谱、顶空-气相色谱-飞行时间质谱以及顶空-气相色谱-串联质谱联用技术对桂花样品进行了分析检测, 并采用多维定性分析思路对检出的挥发性成分进行了鉴定. 结果共确认出47种挥发性成分, 其中单萜类和倍半萜类化合物为主要组分. 该定性分析策略准确可靠, 可以广泛应用于复杂样品挥发性成分的定性分析中.     

高效液相色谱-电喷雾离子阱质谱法鉴定复方丹参方化学及代谢成分

应用高效液相色谱-电喷雾离子阱质谱法鉴定了复方丹参方和其在家兔血浆、尿及粪便中的代谢产物。实验采用ZorbaxC18色谱柱,二元线性梯度洗脱进行色谱分离,并与电喷雾质谱联用,根据正离子和负离子模式下的分子离子峰获得化合物分子量信息,通过与文献数据或部分对照品对照,确定化合物的可能结构。     

姜科姜黄属植物有效成分的研究

研究不同产地姜科姜黄属植物挥发油的化学成分,了解不同产地姜科姜黄属植物挥发性成分的差别,为控制其药材质量提供理论依据。采用水蒸气蒸馏法提取不同产地姜科姜黄属植物的挥发油,用气相色谱—质谱联用仪对其进行分离测定,结合计算机检索对分离的化合物进行结构鉴定,应用色谱峰面积归一化法测定各成分的相对百分含量。结果发现,不同产地姜科姜黄属植物的水蒸气蒸馏提取物得率在0．20％～2．13％之间,分别鉴定出24～40个化学成分。不同品种、不同产地姜科姜黄属植物的挥发油含量和其所含成分有较大差别,文献报道的某些有效成分如莪术酮、莪术二酮、莪术醇和表莪术酮在某些供试品中未检测到。实验中10个供试品药材中挥发性成分主要为单萜类及倍半萜类化合物及其衍生物,倍半萜类化合物的百分含量(44．57％～88．65％)明显高于单萜类化合物的百分含量(1．63％～26．69％)。     

姜黄中两个新没药烷型倍半萜成分的研究

从购自安徽亳州中药材市场的姜黄(Curcuma longa L.)切片95%乙醇提取物中,除主要没药烷型倍半萜类成分芳姜黄酮[(+)-(S)-ar-turmerone]外,还分离得到2个新的同类化合物,turmerones E(1)和F(2).它们的结构通过质谱、一维/二维核磁共振谱和圆二色谱(ECD)等波谱和光谱技术得以确定.     

制备反相高效液相色谱法用于从杉材中分离制备倍半萜类化合物

利用制备高效液相色谱法从日本产杉材(Cryptomeria japonica D.Don)中分离制备倍半萜类化合物。在YWC-Pack C18柱上,以异丙醇-甲醇-正己烷-水(体积比为50∶35∶10∶5)为流动相,流速为5 mL/min,制备了2种倍半萜类化合物,经紫外光谱、红外光谱及核磁、质谱分析,确认它们分别为(-)-cubebol和(+)-2,7(14),10-bisa-bolatrien-1-ol-4-one。所制备的两个化合物的纯度分别为98.7%和99.1%。     

异叶三宝木枝叶中一个新的Stemodane型二萜类化合物

综合运用硅胶柱色谱、反相硅胶柱色谱、Sephadex LH-20凝胶柱色谱以及制备型高效液相色谱等色谱分离技术对大戟科三宝木属植物异叶三宝木Trigonostemon heterophyllus枝叶中的化学成分进行了系统研究,从其枝叶的85%乙醇提取物中分离得到了8个二萜类化合物.采用多种波谱鉴定技术确定了这些化合物的化学结构.其中一个化合物为新的罕见的stemodane型二萜类化合物,七个化合物为首次从三宝木属植物中分离得到的化合物.所有化合物的体外细胞毒活性评价结果表明,它们对五种肿瘤细胞株(HL-60、A549、SMMC-7721、MCF-7和SW480)均显示出了较为显著的体外生长抑制活性,它们的细胞毒活性与抗肿瘤阳性对照药顺铂的活性相当.     

萜类化合物的QSRR研究及其在结构鉴定中的应用

采用顶空固相微萃取(SPME)-气相色谱质谱(GC-MS)联用技术分析石香薷和腊梅鲜花中的萜类化合物, 通过保留指数与质谱解析相结合, 分别对化合物进行结构鉴定, 共鉴定出17种单萜化合物, 30种倍半萜化合物. 采用遗传算法(GFA)分别对单萜及倍半萜化合物建立定量结构-色谱保留关系(QSRR)预测模型, 并对该模型进行显著性及预测能力的检测. 同时, 利用计算所得到的模型分别对随机选取的几个萜类化合物进行保留指数预测. 结果表明: 计算保留指数与预测保留指数接近, 模型预测性能较好. 该研究为各种单萜化合物及倍半萜化合物保留指数的预测提供了一种有效手段, 同时, 为建立有效的GC-MS定性方法提供了一定的依据.     

珊瑚中五环半缩醛甾体的结构解析

为研究珊瑚Sinularia sp.中五环半缩醛甾醇的分离与结构,运用普通色谱及高效液相色谱等色谱方法对珊瑚Sinularia sp.中五环半缩醛甾醇化合物进行分离纯化,通过分析该化合物的核磁共振谱与质谱确定其平面结构,测定并比较圆二色光谱计算值确定化合物的立体构型。结果从珊瑚Sinularia sp.中首次分离纯化得到结构独特的五环半缩醛甾醇化合物(8R,9S,10R,13R,14S,17R,18R,20S,22R)-胆甾-1,4-二烯-18-乙酰基-22-氧-3-酮-18,22-环缩醛。     

全二维气相色谱/飞行时间质谱用于烟叶中酸性成分的分离与分析

建立了烟叶中酸性化合物(挥发性、 半挥发性羧酸类和酚类)组成研究的全二维气相色谱/飞行时间质谱(GC×GC-TOFMS)分析方法, 并用此方法对香料烟中的酸性化合物进行了表征. 用同时蒸馏萃取样品的前处理方法, 采用TOFMS谱图库检索结合全二维特有的包含结构信息的二维谱图, 通过族分离和结构谱图, 鉴定出了香料烟中143种挥发性及半挥发性酸性组分, 包括10种酸酐和呋喃二酮, 43种有机酸和90种酚类化合物. 同时对不同类别的化合物在二维气相色谱上的分布模式进行了研究. 结果表明, 全二维气相色谱飞行时间质谱的高分辨率非常适合于烟叶这类复杂体系的分离分析.     

中药紫花地丁黄酮碳苷类化学成分的超高效液相色谱-电喷雾离子源-四极杆飞行时间串联质谱研究

采用超高效液相色谱-电喷雾离子源-四极杆飞行时间串联质谱(UPLC-ESI-QTOF-MS/MS)方法,以中药紫花地丁中分离得到的5个黄酮碳苷化合物为对照品,研究了黄酮二糖碳苷类化合物在ESI-QTOF-MS/MS质谱中的裂解规律。研究进一步证实了文献报道的黄酮二糖碳苷C-6位取代糖基较C-8位糖更易优先发生裂解;但同时发现结构中如果含有不稳定构象的糖基取代时,该规律不再适用。通过对照品的质谱裂解规律,并结合文献和高分辨质谱数据,成功表征和鉴定了紫花地丁中21个黄酮二糖碳苷类以及4个黄酮氧苷类成分。该方法能快速、灵敏、准确地对中药中微量黄酮碳苷类成分的结构进行表征和鉴定。     

Residue measurement of pendimethalin in tobacco by using heart‐cutting two dimensional liquid chromatography coupled with tandem mass spectrometry

A novel heart‐cutting two‐dimensional liquid chromatography coupled with tandem mass spectrometry method was developed for quantitative analysis of pendimethalin residue in tobacco. The strategy of reversed phase liquid chromatography coupled with another reversed‐phase liquid chromatography was employed for high column efficiency and excellent compatibility of mobile phase. In the first dimensional chromatography, a cyano column with methanol/water as the eluent was applied to separate pendimethalin from thousands of interference components in tobacco. By heart‐cutting technique, which effectively removed interference components, the target compound was cut to the second dimensional C18 column for further separation. The pendimethalin residue was finally determined by the tandem mass spectrometry under multiple reaction monitoring reversed‐phase liquid chromatography mode. Sample pretreatment of the new method was simplified, involving only extraction and filtration. Compared with traditional methodologies, the new method showed fairly high selectivity and sensitivity with almost no matrix interference. The limit of quantitation for pendimethalin was 1.21 ng/mL, whereas the overall recoveries ranged from 95.7 to 103.3%. The new method has been successfully applied to non‐stop measure of 200 real samples, without contamination of ion source. Detection results of the samples agreed well with standard method.     

亲水/反相二维制备液相色谱法分离纯化络石藤中的化学成分

建立了亲水/反相二维制备液相色谱(Pre-2D-HILIC/RPLC)分离纯化络石藤中化学成分的分析方法。络石藤药材经醇提、活性炭脱色后用反相固相萃取柱除去色素和强极性物质,最终得到干燥的浅黄色粉末。一维亲水色谱选择Click XIon色谱柱(250 mm×20 mm,10μm)作为固定相,水和乙腈作为流动相,进行梯度洗脱,以紫外触发模式收集馏分,共得到15个组分。二维反相色谱选择C18色谱柱(250 mm×20 mm,5μm)作为固定相,水和乙腈作为流动相,进行梯度洗脱,最终得到14个高纯度化合物,并通过质谱和核磁共振对其进行确认。实验结果表明,该法具有良好的正交选择性,可以有效提高分离度和峰容量,对于分离络石藤等复杂样品具有重要意义。     

离线二维液相色谱法分离巴天酸模根的化学成分

建立了离线二维反相/反相液相色谱分离体系（2D-RPLC/RPLC）,对巴天酸模中的化学成分进行分离。通过比较巴天酸模乙酸乙酯萃取液在环氧四氮唑和Unitary C18色谱柱上的高效液相色谱图,确定以环氧四氮唑色谱柱为第一维色谱柱,以Unitary C18色谱柱为第二维色谱柱。流动相均采用0.1%（v/v）甲酸水溶液和甲醇,梯度洗脱。经一维色谱分离后,共收集18个流分,采用二维色谱对这18个流分进行了进一步的分离分析。实验结果表明,该二维色谱分离方法高效、可行,为巴天酸模药材的微量组分的分离以及活性化合物的筛选提供了分离方法。     

Characterization of impurities in sisomicin and netilmicin by liquid chromatography/mass spectrometry

The characterization of unknown impurities present in netilmicin and sisomicin by liquid chromatography (LC) coupled with mass spectrometry (MS) is described. The volatile ion-pairing agent trifluoroacetic acid (TFA) was used for the retention of the main compounds and their impurities on a reversed-phase (RP) C18 column, because they are highly hydrophilic and basic compounds. The method showed good separation between netilmicin and its four potential related substances prescribed in the European Pharmacopoeia, which were identified by comparison of their retention times with those of the reference substances. Furthermore, in total 16 unknown impurities in a netilmicin sample and six in a sisomicin sample with unknown identity were detected. The structures of the unknown compounds were deduced based on comparison of fragmentation patterns with those of the reference substances investigated in LC/MSn experiments by the use of electrospray ion trap mass spectrometry.     

Separation and identification of terpene-conjugated curcuminoids based on liquid chromatography–tandem mass spectrometry and their in vitro anti-inflammatory activities

Terpene-conjugated curcuminoids are conjugates of curcuminoids and bisabolanes in the rhizomes of Curcuma longa L. The fragmentation pathways of known three terpene-conjugated curcuminoids (bisabolocurcumin-ether, bisabocurcumin, and demethoxybisabolocurcumin ether) and curcumin, demethoxycurcumin, and bisdemethoxycurcumin were investigated using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry in negative mode to rapidly search and discover similar unknown compounds of the acetone fraction of turmeric. Subsequently, compounds 1–3 were founded in the acetone fraction based on molecular weight and above fragmentation pathways (the characteristic fragment ions, the most and second most abundant fragment ions produced in MS² spectra). Terpecurcumin X ( 1 ) and terpecurcumin Y ( 3 ) were further separated by liquid chromatography–tandem mass spectrometry guided isolation technique to verify their structures by nuclear magnetic resonance, electrospray ionization high-resolution mass spectroscopy, ultraviolet and visible spectra and infrared spectra. Interestingly, 1 and 3 were new compounds. The results indicate the feasibility and significant advantages of liquid chromatography–tandem mass spectrometry for the rapid discovery and analysis of new constituents in traditional Chinese medicine. In vitro, Terpene-conjugated curcuminoids had better nitric oxide inhibitory activity than the other seven curcuminoids (demethoxycurcumin, bisdemethoxycurcumin, curdione, curcumenone, bisacurone, curcumenol, and germacron).     

全二维微柱液相色谱-质谱鉴定人胃癌组织中的差异蛋白质

构建了以阳离子交换色谱-反相色谱(SCX-RPLC)为分离模式的新型全二维微柱液相色谱-质谱分离平台.采用了醋酸铵缓冲液梯度洗脱,实现了第一维肽段的分步洗脱,洗脱的肽段经富集除盐后通过接口进入反相色谱微柱,通过线性梯度实现第二维进一步分离,最后进入质谱进行检测.采用此平台分析了人胃癌组织与正常组织提取蛋白质信息,其中正常胃组织鉴定蛋白质数为537个,而癌症组织鉴定蛋白质数目为506个.对胃癌和正常组织两种提取蛋白质酶解产物的蛋白质检索结果进行比较分析,将鉴定的蛋白质按照物理性质进行分布,找出正常组织与癌症组织间蛋白质差异,筛选出一种可能发生变异的癌症特有蛋白.     

Chemical profiling of bioactive constituents in hop cones and pellets extracts by online comprehensive two‐dimensional liquid chromatography with tandem mass spectrometry and direct infusion Fourier transform ion cyclotron resonance mass spectrometry

Humulus lupulus L. (hop) is highly interesting from a nutraceutical perspective. The hop phytocomplex contains a wide range of bioactive metabolites, and its characterization is challenging. To tackle such a task, for the first time we applied and compared a combined approach consisting of online comprehensive two‐dimensional liquid chromatography with tandem mass spectrometry and direct infusion Fourier transform ion cyclotron mass spectrometry. A reversed phase × reversed phase approach with a shifted gradient in the second dimension ensured selectivity and two‐dimensional space coverage. Hyphenation with an ion trap time‐of‐flight analyzer led to the identification of 83 compounds in 70 min, comprising a novel quercetin derivative and six unknown bitter acids. On the other hand, the direct infusion method was able to identify 40 analytes (except isomers) with high mass accuracy (≤ 0.1 ppm) in less than 1 min analysis time. The developed approach can be used in a complementary way, combining the separation capability and high informative spectra of two‐dimensional liquid chromatography tandem mass spectrometry with the ultra‐high mass accuracy of direct infusion, for potential compound discovery or the accurate profiling of bioactive compounds in different hop cultivars as well as for monitoring processing and storage of hop‐based products.     

Rapid characterization of the chemical constituents of Cortex Fraxini by homogenate extraction followed by UHPLC coupled with Fourier transform ion cyclotron resonance mass spectrometry and GC–MS

Cortex Fraxini is an important traditional Chinese medicine. In this work, a rapid and reliable homogenate extraction method was applied for the fast extraction for Cortex Fraxini, and the method was optimized by response surface methodology. Ultra high performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry and gas chromatography with mass spectrometry were established for the separation and characterization of the constituents of Cortex Fraxini. Liquid chromatography separation was conducted on a C₁₈ column (150 mm × 2.1 mm, 1.8 μm), and gas chromatography separation was performed on a capillary with a 5% phenyl‐methylpolysiloxane stationary phase (30 m × 0.25 mm × 0.25 mm) by injection of silylated samples. According to the results, 33 chemical compounds were characterized by liquid chromatography with mass spectrometry, and 11 chemical compounds were characterized by gas chromatography with mass spectrometry, and coumarins were the major components characterized by both gas chromatography with mass spectrometry and liquid chromatography with mass spectrometry. The proposed homogenate extraction was an efficient and rapid method, and coumarins, phenylethanoid glycosides, iridoid glycosides, phenylpropanoids, and lignans were the main constituents of Cortex Fraxini. This work laid the foundation for further study of Cortex Fraxini and will be helpful for the rapid extraction and characterization of ingredients in other traditional Chinese medicines.     

Online high‐pH reversed‐phase liquid chromatography × low‐pH reversed‐phase liquid chromatography tandem electrospray ionization mass spectrometry combined with pulse elution gradient in the first dimension for the analysis of alkaloids in Macleaya cordata (willd.) R. Br

An online high‐pH reversed‐phase liquid chromatography× low‐pH reversed‐phase liquid chromatography tandem electrospray ionization mass spectrometry combined with pulse elution gradient in the first dimension was constructed to separate and identify alkaloids from Macleaya cordata (willd.) R. Br. The modulation was performed by using a dual second dimensional columns interface combined with a make‐up dilution pump, which is responsible for dilution and neutralization of the first dimensional effluent, and the dual second dimensional columns integrated the trapping and the separation function to reduce the second dimension system dead volume. Taking advantage of the dissociable characteristics of alkaloids, mobile phases with different pH values were applied in the first dimension (pH 9.0) and the second dimension (pH 2.6) to improve the orthogonality of two‐dimension separation. Besides, the pulse elution gradient in first dimension and second dimensional gradient were carefully optimized and much better separation was achieved compared to the separation with the traditional two‐dimensional liquid chromatography approach. Finally, mass measurement was performed for alkaloids in M. cordata (willd.) R. Br. by coupling proposed two‐dimensional liquid chromatography system with triple quadrupole mass spectrometry, and 39 alkaloids were successfully identified by comparing the obtained result with the former reported results.     

Chemical profiling of Ziziphi spinosae semen using on-line comprehensive two-dimensional liquid chromatography-mass spectrometry based on a novel phthalic anhydride bonded stationary phase

Ziziphi spinosae semen has been widely used to treat insomnia and anxiety. To profile its chemical components, an online comprehensive two-dimensional liquid chromatography-mass spectrometry was developed. In this two-dimensional liquid chromatography system, a novel phthalic anhydride-bonded stationary phase column was combined with a C18 column. As a result, this new stationary phase exhibited remarkable differences in separation selectivity from C18, achieving a good orthogonality of 83.3%. Moreover, this new stationary phase with weaker hydrophobicity than C18 realized solvent compatibility in the online configuration. Coupled with tandem MS, 154 compounds were identified, including 51 unreported compounds. Compared with one-dimensional liquid chromatography-mass spectrometry, this online two-dimensional liquid chromatography-mass spectrometry system exhibited a much higher resolving power in isomer separation. This work provided an effective separation and characterization method for the material basis of Ziziphi spinosae semen. This strategy provides ideas for the material basis research of other traditional Chinese medicines.