代谢组学血浆样品前处理及其快速高分辨液相色谱-质谱分析方法研究

采用快速高分辨液相色谱-质谱联用技术,对代谢组学研究中血浆样品的前处理方法进行了考察及优化,建立了用于血浆中小分子代谢物分析的前处理方法.通过考察有机溶剂沉淀蛋白(不同溶剂系统)和固相萃取(Solid phase extraction,SPE)两种方法对血浆中蛋白质去除程度及16个代表性化合物的提取效果,确定采用乙腈沉...     

嗜酸性氧化亚铁硫杆菌代谢产物的常压化学电离质谱分析

本研究以721矿和745矿嗜酸性氧化亚铁硫杆菌为研究对象,采用常压化学电离质谱直接分析其代谢产物,分别考察了顶空采样( Headspace sampling)、界面采样( Interface sampling)和中性解吸采样( Neutral desorption sampling)3种进样方式对电离效果的影响。在优化条件下,常压化学电离质谱对微生物纯菌种和混合菌种的代谢产物均具有良好的分析能力,可根据获得的代谢产物指纹谱图结合主成分分析( PCA)方法和聚类分析( CA)方法区分2个放射性强弱不同区域共4类嗜酸性微生物样品,并对主要胺类、酯类等代谢成分进行串联质谱鉴定,为耐辐射微生物的相关研究提供了一种可借鉴的分析方法。     

高分辨质谱技术在中药分析中的研究进展

中药分析涉及中药物质基础研究、药物代谢、中药质量控制等多个领域,是中药现代化研究的基础。随着现代化分析技术的发展,中药分析研究取得了极大的进展。针对中药成分复杂、代谢过程多样、目标物浓度低等难点,高分辨质谱技术凭借精确质量数、高分辨率及高灵敏度的优点在中药分析中具有显著优势。该文对高分辨质谱技术在中药分析中的应用进行了综述,重点介绍了四极杆飞行时间质谱、静电场轨道阱质谱、傅里叶变换离子回旋共振质谱和离子淌度串联质谱等质谱技术的发展,以及高分辨质谱在中药化学成分鉴定、中药化合物代谢研究、中药植物代谢组学研究以及中药有害化学成分检测中的研究进展。同时,对高分辨质谱在中药分析中的应用进行了展望,以期促进中药现代化发展。     

基于液相色谱-质谱法的不同花期金银花代谢组学分析

基于液相色谱-质谱(LC-MS)建立了金银花代谢组学分析方法,优化得到最佳提取试剂为甲醇-水(体积比3∶1),并对方法的重复性和精密度进行了考察。结果表明方法的稳定性良好,满足代谢组学分析的要求。通过质量数、保留时间和二级质谱数据对金银花中的初生和次生代谢物进行了定性分析,共鉴别出157个代谢物,包括氨基酸、核苷、脂肪酸、脂质等初生代谢物以及酚酸、黄酮、环烯醚萜苷等次生代谢物。不同花期的金银花代谢组学分析发现,次生代谢物酚酸类、黄酮类和环烯醚萜苷类的含量随着花期的增加而显著下降。初生代谢物中,大部分氨基酸、核苷、氧化脂肪酸的含量显著下降,而大部分的溶血磷脂酰胆碱(Lyso PC)、溶血磷脂酰乙醇胺(Lyso PE)和脂肪酸的含量显著上升。该研究结果可为金银花药效成分代谢调控机制的深入研究及后期种植采收提供理论指导。     

金属/基质增强飞行时间-二次离子质谱用于单细胞脂质分析

单细胞中化学成分的分析对细胞生长、信号转导、凋亡等生理过程意义重大。飞行时间-二次离子质谱(SIMS)是一种高灵敏的表面质谱成像技术,具有较高的空间分辨率,已被用于细胞及微区域分析。然而,生物有机分子较低的离子化效率限制了To F-SIMS在单细胞分析中的广泛应用。本研究采用金属/基质增强方法,明显提高了脂质的离子化产率。镀金硅片上磷脂酰胆碱PC(40:0)标样在加入基质后,准分子离子峰强度增大为硅片上的65倍。相应基底上单细胞表面脂质信号同时增强,但由于细胞的不规则形貌以及复杂化学环境影响,脂质信号增强幅度较小。在此基础上,使用延时提取(Delayed extraction,DE)模式克服了细胞形貌带来的影响,进一步增强脂质信号,并获得了高质量的单细胞脂质成像图。此方法为研究细胞代谢及细胞-环境相互作用提供了新的途径。     

新型杀菌剂唑菌酯吡唑环14C标记合成和鉴定

为研究新型杀菌剂唑菌酯在土壤中的代谢途径、作用机理及环境行为,以14C-对氯苯甲酸为原料,通过取代、环化、缩合三步反应合成吡唑环14C标记的唑菌酯.采用高效液相色谱-质谱联用仪(电喷雾离子源)[HPLC-MS(ESI)],质谱法(电子轰击离子源)[MS(EI)],核磁共振氢谱法(1H NMR)验证了其结构,通过HPLC...     

脂质组学血清样品处理方法及其快速高分辨液相色谱-质谱分析

通过系统考察血清样本前处理方法、优化液相色谱条件及质谱检测参数,建立了脂质组学血清样本前处理及其快速高分辨液相色谱-质谱(RRLC-MS)分析方法。血清样本中加入二氯甲烷-甲醇(CH2Cl2-CH3OH,2∶1,V/V)混合溶剂进行脂质提取,采用ACQUITY UPLC CSH C18色谱柱(100 mm×2.1mm,1.7μm),以10 mmol/L甲酸铵溶液(含0.1%甲酸)为流动相A,乙腈-异丙醇(1∶1,V/V)为流动相B,梯度洗脱,采用正负离子检测模式电喷雾电离(±)ESI、正离子检测模式大气压化学电离(+)APCI方式进行质谱检测。对血清中脂肪酸、甘油脂、鞘磷脂、甘油磷脂和胆固醇(酯)5类14种代表性脂质类成分进行了方法学考察。结果表明,方法灵敏度高、精密度及稳定性良好。对穿插在检测序列中的质控样本检测结果进行主成分分析(PCA),证明了本方法获得数据的可靠性良好,适用于脂质组学研究。     

脂组学及其研究进展

脂质的生物功能具有多样性,其代谢与多种疾病的发生、发展密切相关.脂质的分析量化对研究疾病发生机理和诊断治疗,以及医药研发有非常重要的生物学意义.分析技术的快速发展,特别是质谱及其联用技术的运用,促使脂质分析不断完善.脂组学就是对生物样本中脂质的整体分析,是代谢组学的重要组成部分,能够促进代谢组学的发展.本文就脂质的生物功能、脂质分析以及脂组学的研究现状作简要评述.     

常压电离质谱在脂质精确结构解析中的研究进展

脂类化合物的结构和功能与细胞生理过程密切相关,脂质结构的精确解析对探索脂质的生物学功能起着至关重要的作用.常压电离质谱技术的出现为常压敞开环境条件下的原位、实时、直接、快速生物脂质分析和组学研究提供了重要的手段.随着常压电离质谱技术在脂质分析和脂质组学研究的不断深入,对脂质结构特别是碳碳双键(C=C)位置的精细解析就显...     

SPE和QuEChERS前处理方法结合LC-Q-TOF/MS检测苹果和番茄中282种农药残留对比研究

利用液相色谱-四极杆/飞行时间质谱(LC-Q-TOF/MS)对比研究了固相萃取(SPE)和Qu ECh ERS两种前处理方法在282种农药残留检测上的效果。以苹果和番茄为基质,分别从基质效应、回收率、重复性、线性关系、检出限和定量限等方面进行了考察与比较。SPE法和Qu ECh ERS法在苹果中呈现出弱基质效应的农药占比分别为87.2%和57.1%,在番茄中为65.6%和42.2%。与SPE相比,Qu ECh ERS法干扰物较多,基质效应较强;在5.0μg/kg添加水平下(n=5),SPE和Qu ECh ERS在苹果中平均回收率在70%~120%的农药占比分别为99.3%和86.9%,在番茄中为92.9%和87.9%;在5.0μg/kg添加水平下(n=5),SPE和Qu ECh ERS在苹果中重复性相对标准偏差(RSD)20%(n=5)农药占比分别为98.9%和86.5%,在番茄中为92.9%和87.6%;SPE和Qu ECh ERS两种方法在苹果中定量限≤10μg/kg的农药占比为100.0%和96.1%,在番茄中为100.0%和98.9%。两种前处理方法均能与高分辨质谱技术相结合并应用于果蔬农药残留的日常检测中,其中SPE净化效果较优,定量更为准确,但步骤稍显繁琐费时,而Qu ECh ERS方法简单快速,故在检测时可根据不同需要进行选择。     

Identification of lipophilic bioproduct portfolio from bioreactor samples of extreme halophilic archaea with HPLC-MS/MS

Extreme halophilic archaea are a yet unexploited source of natural carotenoids. At elevated salinities, however, material corrosivity issues occur and the performance of analytical methods is strongly affected. The goal of this study was to develop a method for identification and downstream processing of potentially valuable bioproducts produced by archaea. To circumvent extreme salinities during analysis, a direct sample preparation method was established to selectively extract both the polar and the nonpolar lipid contents of extreme halophiles with hexane, acetone and the mixture of MeOH/MTBE/water, respectively. Halogenated solvents, as used in conventional extraction methods, were omitted because of environmental considerations and potential process scale-up. The HPLC-MS/MS method using atmospheric pressure chemical ionization was developed and tuned with three commercially available C₄₀ carotenoid standards, covering the wide polarity range of natural carotenoids, containing different number of OH-groups. The chromatographic separation was achieved on a C₃₀ RP-HPLC column with a MeOH/MTBE/water gradient. Polar lipids, the geometric isomers of the C₅₀ carotenoid bacterioruberin, and vitamin MK-8 were the most valuable products found in bioreactor samples. In contrast to literature on shake flask cultivations, no anhydrous analogues of bacterioruberin, as by-products of the carotenoid biosynthesis, were detected in bioreactor samples. This study demonstrates the importance of sample preparation and the applicability of HPLC-MS/MS methods on real samples from extreme halophilic strains. Furthermore, from a biotechnological point-of-view, this study would like to reveal the relevance of using controlled and defined bioreactor cultivations instead of shake flask cultures in the early stage of potential bioproduct profiling.     

Lipidomic analysis of polyunsaturated fatty acids and their oxygenated metabolites in plasma by solid-phase extraction followed by LC-MS

The present work describes the development of a robust and sensitive targeted analysis platform for the simultaneous quantification in blood plasma of lipid oxygenated mediators and fatty acids using solid-phase extraction (SPE) and high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). The concurrent analysis of these lipid mediators is challenging because of their instability, differences in solubility, and the frequent occurrence of isobaric forms with similar fragmentation patterns. Results demonstrated that the reduction of SPE temperature to 4 °C is a critical parameter for preserving the hydroperoxy derivatives. Polymeric HLB cartridges increased 40–50 % ARA, EPA, and DHA sensitivity compared to C18 sorbent and also provided higher global performance for most hydroxides and other oxidation products. The proposed method for the two tested mass analyzers yields high sensitivity, good linearity, and reproducibility, with detection limits ranging 0.002–7 ng/mL and global recoveries as high as 85–112 %. However, the additional advantage of the linear ion trap (LIT) mass analyzer working in full scan product ion mode, compared to the triple quadrupole (QqQ) operating in multiple reaction monitoring (MRM), should be noted: the full scan product ion mode provides the full fragmentation spectra of compounds that allowed the discrimination of coeluting isomers and false positive identifications without additional chromatography development. The proposed lipidomic procedure demonstrates a confident, simple, and sensitive method to profile in plasma a wide range of lipid eicosanoid and docosanoid mediators, including innovatively the analysis of hydroperoxy congeners and nonoxidized PUFA precursors.

Solid-phase extraction for multiresidue determination of sulfonamides, tetracyclines, and pyrimethamine in Bovine's milk

This paper describes a systematic approach to the development of a solid-phase extraction method for simultaneous extraction of 10 antibiotic residues in bovine milk, belonging to groups of sulfonamides, tetracyclines, and pyrimethamine. The sample preparation steps include acidic deproteinization of milk proteins followed by sample enrichment and cleanup using a polymer-based Oasis HLB solid-phase extraction cartridge. The analyses were carried out by using a method based on liquid chromatography-electrospray ionisation-mass spectrometry with positive ion mode. The parameters affecting the extraction efficiency such as sample loading pH, SPE wash solvent composition, and eluting solution pH were carefully investigated and optimized. The developed solid-phase extraction procedure coupled to multiresidue liquid chromatography-electrospray ionization-mass spectrometry method was applied for the analysis of 10 antibiotic residues in milk samples, and it proved to be simple, sensitive, and selective providing a recovery ranging from 70 to 106%.     

超高效液相色谱-高分辨质谱确证分析泥鳅体内五氯酚代谢物

建立了超高效液相色谱-高分辨质谱(UPLC-HRMS)鉴定泥鳅体内五氯酚代谢物五氯酚磺酸酯的方法。将在低浓度五氯酚下暴露的泥鳅样品粉碎,采用含8%(体积分数)三乙胺的70%(体积分数)乙腈水溶液提取,经混合阴离子交换小柱萃取净化,在ACQUITY BEH C18色谱柱(100 mm×2.1 mm,1.7μm)上分离,采用电喷雾负离子(ESI-)一级质谱全扫描加数据依赖的二级质谱扫描(full mass-ddMS2)模式测定,获得代谢物的准分子离子、同位素离子和二级质谱碎片离子的精确质量数。结果表明,五氯酚在泥鳅体内的代谢以磺化为主,没有发现羟基化和葡萄糖醛酸化。代谢物主要为五氯酚磺酸酯,其含量随着暴露时间(t)的延长逐渐增加,当暴露时间为36 h时达到峰值,随后逐渐减小,当t≥120 h时,五氯酚磺酸酯含量基本维持不变。该方法可用于生物体内五氯酚的代谢研究。     

On-line solid phase extraction LC-MS/MS analysis of pharmaceutical indicators in water: A green alternative to conventional methods

A method using automated on-line solid phase extraction (SPE) directly coupled to liquid chromatography/tandem mass spectrometry (LC-MS/MS) has been developed for the analysis of six pharmaceuticals by isotope dilution. These selected pharmaceuticals were chosen as representative indicator compounds and were used to evaluate the performance of the on-line SPE method in four distinct water matrices. Method reporting limits (MRLs) ranged from 10 to 25 ng/L, based on a 1 mL extraction volume. Matrix spike recoveries ranged from 88 to 118% for all matrices investigated, including finished drinking water, surface water, wastewater effluent and septic tank influent. Precision tests were performed at 50 and 1000 ng/L with relative standard deviations (RSDs) between 1.3 and 5.7%. A variety of samples were also extracted using a traditional off-line automated SPE method for comparison. Results for both extraction methods were in good agreement; however, on-line SPE used approximately 98% less solvent and less time. On-line SPE coupled to LC-MS/MS analysis for selected indicators offers an alternative, more environmentally friendly, method for pharmaceutical analysis in water by saving time and costs while reducing hazardous waste and potential environmental pollution as compared with off-line SPE methods.     

Lipid fingerprinting of gram-positive lactobacilli by intact--matrix-assisted laser desorption/ionization mass spectrometry using a proton sponge based matrix

A method of direct lipid analysis by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) in intact membranes, without prior extraction/separation steps, is described. Here, we demonstrate the efficacy of a strong base, 1,8-bis(dimethylamino)naphthalene (DMAN; proton sponge), as a novel matrix for MALDI-time-of-flight (TOF) MS analysis of whole cell bacteria. Initially, individual acidic low-molecular-weight analytes such as standard free fatty acids and phospholipids were analyzed using DMAN as matrix. Clear negative-mode MALDI-TOF MS spectra of all analytes show only deprotonated analyte signals at a low picomole limit of detection with the complete absence of matrix-related signals. These results indicate that DMAN represents a suitable matrix for MALDI-TOF MS analysis of mixtures of complex lipids as the intact membranes of microorganisms. DMAN was successfully applied to the analysis of Lactobacillus sanfranciscensis and L. plantarum microorganisms. Different components were sensitively detected in a single spot, including 16:0, 18:2, 18:3, and 21:0 free acids, glycolipids, phosphatidylglycerols (PGs) and cardiolipins. This method might be of general application, offering the advantage of quickly gaining information about lipid components of other gram-positive bacterial membranes.     

New insight in the structural features of haloadaptation in α-amylases from halophilic Archaea following homology modeling strategy: folded and stable conformation maintained through low hydrophobicity and highly negative charged surface

Proteins from halophilic archaea, which live in extreme saline conditions, have evolved to remain folded, active and stable at very high ionic strengths. Understanding the mechanism of haloadaptation is the first step toward engineering of halostable biomolecules. Amylases are one of the main enzymes used in industry. Yet, no three-dimensional structure has been experimentally resolved for α-amylases from halophilic archaea. In this study, homology structure modeling of α-amylases from the halophilic archaea Haloarcula marismortui, Haloarcula hispanica, and Halalkalicoccus jeotgali were performed. The resulting models were subjected to energy minimization, evaluation, and structural analysis. Calculations of the amino acid composition, salt bridges and hydrophobic interactions were also performed and compared to a set of non-halophilic counterparts. It clearly appeared that haloarchaeal α-amylases exhibited lower propensities for helix formation and higher propensities for coil-forming regions. Furthermore, they could maintain a folded and stable conformation in high salt concentration through highly negative charged surface with over representation of acidic residues, especially Asp, and low hydrophobicity with increase of salt bridges and decrease in hydrophobic interactions on the protein surface. This study sheds some light on the stability of α-amylases from halophilic archaea and provides strong basis not only to understand haloadaptation mechanisms of proteins in microorganisms from hypersalines environments but also for biotechnological applications.     

An LC-MS-MS Method for the Determination of Perfluorinated Surfactants in Environmental Matrices

Recently, there has been increasing concern about perfluorinated surfactants, especially perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) due to their persistence and chronic toxicity in the aquatic environment. Solid phase extraction (SPE) followed by liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS) are widely applied to quantitatively identify PFOS and PFOA. However, the application of this powerful analytical technique is limited by matrix susceptibility. The co-eluting matrix components in the SPE extracts affect the ionization efficiency and lead to erroneous results. An efficient sample clean-up method was developed in this study to significantly remove co-eluting matrix components by applying the SPE extracts onto a silica cartridge. It was shown that matrix effect (ME%) increased to >70% for both PFOS and PFOA in the analysis of raw sewage. Internal standardization was used to further compensate for the matrix effect, which also proved to improve the signal reproducibility. The clean-up method described in this study was applied to different water samples (surface water and wastewater) to evaluate the efficiency of silica clean-up and the influence of sample origin on the matrix effect. ME% and recovery efficiency (RE%) were in the range of 91.9–98.3% and 89.2–98.0%, respectively. Results showed that the developed method is robust and can be applied to analyze PFOS and PFOA in different environmental matrices.     

SPE – Microwave‐assisted extraction coupled system for the extraction of pesticides from water samples

SPE is a commonly applied technique for preconcentration of pesticides from water samples. Microwave‐assisted extraction (MAE) technique is the extraction applied for preconcentration of different compounds from solid samples. SPE coupled with MAE is capable of preconcentrating these compounds from water samples too. This investigation was aimed at improving the efficiency of atrazine, alachlor, and α‐cypermethrin pesticide extraction from the spiked water samples applying SPE followed by MAE. In this way, MAE served for elution of pesticides from C₁₈‐extraction disks with solvent heated by microwave energy. Various elution conditions were tested for their effects on the extraction efficiency of the SPE–MAE combined technique. Several parameters, such as elution solvent volume (mL), elution temperature (°C), and duration of elution (min), affect the extraction efficiency of the SPE–MAE coupled system and need to be optimized for the selected pesticides. In order to develop a mathematical model, 15 experiments were performed in the central composite design. The equation was then used to predict recoveries of the pesticides under specific experimental conditions. Optimization of microwave extraction was accomplished using the genetic algorithm approach. Best results were achieved using 20 mL of ethanol at 60°C. Optimal hold time was 5 min and 24 s. The SPE–MAE combination was also compared with the conventional SPE extraction technique with elution of a nonpolar or a moderately polar compound with nonpolar solvents.     

Optimization and evaluation of a procedure for the gas chromatographic-mass spectrometric analysis of the aromas generated by fast acid hydrolysis of flavor precursors extracted from grapes

A procedure has been developed for the GC-MS analysis of the aromas released in fast acid hydrolysis of precursor fractions from grape musts and skins. Different sorbents for the extraction of the precursors were compared. The best results were obtained with LiChrolut EN polymeric resins which displayed two and six-fold more extraction capacity than Amberlite XAD-2 resins and C18 sorbents, respectively. C18 sorbents are more suitable for selective extraction of less polar precursors. The initial version of the method was imprecise and so the imprecision of the different steps was assessed. The maceration of the solid parts and the liquid-liquid extraction of the aromas released in the acid hydrolysis proved to be the critical steps. Greater crushing of the solid parts and solid-phase extraction (SPE) instead of liquid-liquid extraction (LLE) improved reproducibility. In the method finally proposed about 100 aromatic components belonging to four large groups (lipid derivatives, shikimic acid derivatives, norisoprenoids and terpenes) were determined with good reproducibility. Important aroma compounds, such as cis-rose oxide or wine lactone were detected in non-Muscat grapes.