便携式GC-MS在挥发性有机物应急监测中的应用

建立了便携式GC-MS测定空气中37种挥发性有机物(VOCs)的方法,采用便携式GC-MS配置的手持探头采集大气样品,然后用便携式GC-MS进行检测.该方法能快速、有效地对空气中的37种挥发性有机物进行定性和定量,具有相关性好(r>0.995)、检出限低(0.070×10-9 ～0.94×10-9 (体积分数))、精密度好(RSD小于7.7%)、准确度高(回收率为92% ～114%)的特点,适用于大气中挥发性有机污染物的应急监测.     

GC-MS法测定水源水中的半挥发性有机物

我国于2002年6月1日实施了地表水环境质量标准(GB3838-2002),其中集中式生活饮用水地表水源地特定项目中规定了68种有机污染物的监测,包括挥发性有机物(VOCs)和半挥发性有机物(SVOCs),其中半挥发性有机物的类别较多,有硝基苯、氯苯、苯胺、苯酚、有机氯农药、有机磷农药、多环芳烃和多氯联苯等有机污染物,分析方法以气相色谱为主。     

生活饮用水中有机物的三维荧光特征

采用荧光分光光度计对《生活饮用水卫生标准》(GB5749-2006)中所规定的53种有机污染物的水溶液进行三维荧光扫描,发现其中18种有机物能够发出荧光。在一定浓度范围内,荧光峰值与溶液浓度呈现良好的线性关系,相关系数r2均大于0.9,可用于定量分析,而且这些有机物都有自己的荧光峰位置。因此可以通过有机物的三维荧光特性来快速分析水体中这些有机的污染情况,这些有机物的荧光特性与其所具有的官能团有关。     

当归挥发性有机物的SPME/GC-MS分析

采用不同极性的SPME萃取吸附了当归的挥发性有机物,并用GC-MS定性和相对定量,比较了不同萃取时间和不同萃取温度下所获得的挥发性有机物的差异。结果表明:藁本内酯和α-蒎烯是其主要成分。随着萃取时间的延长,α-蒎烯含量逐渐减少,藁本内酯含量逐渐升高;随着萃取温度的升高,低沸点化合物含量逐渐减少,高沸点化合物含量逐渐增加。     

公交车场挥发性有机物暴露水平的GC-MS测定

空气中的挥发性有机物(volatileorganiccompounds,VOCs)日益受到大家的关注,这不仅因为它们具有强烈的环境效应,而且在较高浓度下可直接危害人体健康。研究表明机动车尾气已成为广州市区VOCs的主要来源,街区VOCs的暴露水平高于北美和欧洲的一些国家。目前很多研究报道了广州公共场所,如街道、商场等地的VOCs暴露水平,公交车场内的VOCs在广州还少有报道,本研究选择了广州某室内公交车场研究其VOCs的暴露水平。     

预浓缩系统与GC-MS联用测定环境空气中痕量挥发性有机物

目前,国内空气质量监测普遍停留在燃煤、汽车尾气引起的无机污染物(二氧化硫、二氧化氮)阶段,而对易对人体产生三致作用(致癌、致畸、致突变)的挥发性有机物(VOCs)监测由于技术原因尚未开展。现在,挥发性有机物(VOCs)对室内外空气质量及人体健康的影响已日益受到人们的关注,同时也成为国内外研究的焦点。本文采用在常温下用抽成真空的苏玛罐(内壁经过抛光处理的金属罐)或Tedlar袋进行采样,然后在实验室用预浓缩仪两级低温浓缩捕集挥发性有机物(VOCs),再进入GC-MS进行定性、定量分析,本方法灵敏度高,重复性好,适合于室内空气和环境空气中挥发性有机物(VOCs)的测定。     

饮用水中挥发性有机物(VOCs)的GC-MS分析

用顶空－毛细管气相色谱－质谱联用仪测定了北京主要区域的自来水,北京目前市场销售的瓶装饮用水（包括天然矿泉水,纯净水等）中２３种挥发性有机物（ＶＯＣｓ）（包括有机氯化物,有机溴代物及苯系物等）的浓度,并与其它城市（如天津,上海,兰州等地）的自来水中ＶＯＣｓ的浓度进行了比较,结果表明北京市区内自来水及大多数市售瓶瓶饮用水中ＶＯＣｓ含量很低。     

生活饮用水中挥发性有害有机污染物分析及其安全性评价

生活饮用水安全性是与人们身体健康休戚相关的问题,除了微生物和重金属外,饮用水中有害有机污染物的存在情况也日益受到人们的关注。从1974年发现氯消毒会产生具有致突变和致癌症的三氯甲烷以来,国际饮用水界研究消毒副产物的工作就没有停止过。大量流行病学研究证明长期饮用氯消毒的水会增加人们得癌症的危险。为此,世界各国和地区都制定了生活饮用水水质标准及规范,以保证人们生活饮用水的安全性。美国《国家饮用水基本规则》对92种污染物做出了硬性规定,世界卫生组织(WHO)则有133项,其中有机物占89项,欧共体有61项,我国卫生部2001年颁布的生活饮用水卫生规范有96项,其中常规检验指标有34项,增加了一些消毒副产物的规定,虽然大部分为非常规项目,但有了相关限定值。本文对有代表性的几种生活饮用水中挥发性有机物进行了分析测定。     

固相萃取-气相色谱-质谱法测定生活饮用水中23种半挥发性有机物的含量

分别从水源、水厂及管网取水样10份,每份水样装满2L棕色玻璃瓶,各加亚硫酸钠100mg去除残余氯,于4℃保存,此水样可保存14d,每升样品中加入20mg·L~(-1)苊-d10和屈艹-d12的混合内标溶液100μL。按国家标准GB/T 5750-2006所述方法进行固相萃取,所得洗脱液经脱水、蒸缩,并用丙酮定容至1.0 mL。选用HP-5MS色谱柱(30 m×0.25 mm,0.25μm),在55～310℃区间按程序升温模式使此溶液中的23种半挥发性有机物得到分离并进行质谱测定。选择了电子轰击离子源和选择离子监测模式为主要质谱条件。各组分的线性范围除五氯酚为1.00～50mg·L~(-1)外,其他均为0.20～10mg·L~(-1),其检出限(3s)在0.03～0.18μg·L~(-1)之间。以阴性样品为基体,用标准加入法进行回收试验,测得回收率在75.5%～124%之间,测定值的相对标准偏差(n=6)在1.1%～16%之间。在所取10份样品中均未检出上述各组分,说明水源及水厂(包括经管网输送至用户的水)均符合国家标准中有关半挥发有机物允许最高存在量的相关要求。     

Critical comparison of automated purge and trap and solid-phase microextraction for routine determination of volatile organic compounds in drinking waters by GC-MS

The use of two automated sample preparation techniques, solid-phase microextraction (SPME) and purge and trap (P&T) systems are critically compared for the GC–MS determination of eight volatile organic compounds (VOCs), including trihalomethanes (THMs), in drinking water samples. Compounds chosen for the comparison are regulated by Spanish and European official guidelines for drinking waters. Experimental parameters investigated for the two sample preparation techniques included SPME type of fibers, SPME modality, P&T gas flow, extraction and desorption times and desorption temperatures. Thus, optimal experimental conditions have been worked out for the SPME and P&T techniques. Under such optimised conditions, detection limits, precision and accuracy were evaluated. Both methods fulfilled the values that the official guidelines establish. The P&T–GC–MS method offers LDs ranged from 0.004 to 0.2 ng mL⁻¹, repeatabilities below 6% and recoveries between 81 and 117%; while LDs ranging from 0.008 to 0.7 ng mL⁻¹, 1–12% R.S.D. and recoveries from 80 to 119% were achieved with the SPME–GC–MS method. Finally, we chose P&T–GC–MS method as the best for this determination and we validate this methodology by its application to the analysis of an Aquacheck Interlaboratory Exercise.     

麻黄-甘草药对配伍过程中的主要药效成分的分析

利用高效液相色谱串联质谱联用法(HPLC-MS/MS)和气相色谱质谱联用法(GC-MS)分析了麻黄与甘草药对配伍前后水煎液中主要药效成分的变化,并通过小鼠的耳廓肿胀试验考察了甘草、麻黄单煎液及药对共煎液的抗炎活性变化。分别通过HPLC法和GC-MS法对甘草与麻黄中主要化学成分,甘草酸、甘草苷、麻黄碱和甲基麻黄碱进行了定量分析,通过单煎液和药对共煎液的对比,发现麻黄与甘草配伍共煎液中麻黄碱（含伪麻黄碱）的含量增加了14.52%;甲基麻黄碱（含甲基伪麻黄碱）的含量增加了64.0%;甘草酸含量增加了13.50%;而甘草苷含量降低了19.38%。药效实验证明,甘草与麻黄配伍后抗炎作用较甘草麻黄单煎液明显增强。从而在主要成分的变化程度上揭示了甘草与麻黄配伍过程中的增效机理。     

PLOT柱分离GC-MS法测定酿酒发酵产品中的微量丁二酮和苯乙烯

食用酒精是利用淀粉质或糖质原料在微生物作用下发酵生成的酒精,丁二酮和苯乙烯是食用酒精生产过程中可能生成或引入的物质。丁二酮具有令人生厌的馊饭味[1],苯乙烯属毒性物质,对人的精神系统、消化系统和造血系统均有一定影响[2]。检测食品中的丁二酮和苯乙烯的方法主要有苯腙     

气相色谱-质谱结合活数据库法测定煤直接液化加氢改质油中C7C9馏分的组成

采用中心切割二维气相色谱,以PONA色谱柱为一维预分析柱与氢火焰离子检测器连接,以DB-35MS色谱柱为二维分析柱与MS连接,对煤直接液化加氢改质油中C7~C9馏分进行了分离与分析,并将质谱谱库检索和活数据库法相结合对60种组分进行了定性分析。同时采用标准物质和烃类化合物在PONA柱上的保留规律对上述定性结果作了验证。还采用面积归一化方法对油样中各化合物进行了定量分析和碳数分布以及族组成分析,其中C8及C9的化合物含量分别为32.3%和51.7%,主要族组成为环烷烃(77.3%)和正构烷烃(9.63%)。     

Multi-residue analysis and ultra-trace quantification of 36 priority substances from the European Water Framework Directive by GC-MS and LC-FLD-MS/MS in surface waters

A multi residue analysis was developed for screening, quantification and confirmation of 36 priority organic compounds included in the 2000/60/EC European Water Framework Directive. The compounds analyzed included 19 pesticides, 8 PAH, 5 endocrine-disruptors and 4 organochlorine compounds. The method was developed in three steps. First, automated off-line solid-phase extraction using Strata X cartridges was optimized to trap simultaneously the 36 studied compounds. Second, the more volatile compounds were analysed by gas chromatography coupled to mass spectrometry with electron impact ionisation in selected ion monitoring mode (SIM). Third, the last 20 compounds were detected and quantified, in one run, by liquid chromatography coupled to fluorescence detector and tandem mass spectrometry. The excellent selectivity and sensitivity allowed us satisfactory quantification and confirmation at levels as low as 0.2-67 ng L⁻¹ with recoveries between 59 and 105%. Such methodology was then applied to French surface waters: all the waters present organic contaminants, and their concentration varied according to the origin and nature of substances.     

加速溶剂萃取-气相色谱-串联质谱法测定烟丝中5种羧酸苯乙酯的含量及对烟丝加香的均匀性评价

将烟丝样品置于温度(20±1)℃及相对湿度(60±3)%条件下平衡24h。称取此样品4.0g置于Dionex ASE 350萃取仪的34 mL萃取池中,用正己烷作为溶剂进行加速溶剂萃取(ASE)。加速萃取的温度为100℃,静态萃取时间为5min,循环次数为2次。于萃取液中加入乙酸苯甲酯内标(100mg·L^-1)溶液0.50mL,混匀后经0.45μm滤膜过滤,取滤液进行气相色谱-串联质谱法分析。采用HP-5MS毛细管色谱柱(30m×0.25mm,0.25μm),在60~280℃温度区间程序升温模式分离后,按电子轰击离子源和多反应监测模式条件进行串联质谱测定。所测定的5种羧酸苯乙酯的质量浓度均在0.10~10.00mg·L^-1内与其对应的峰面积之间呈线性关系,其检出限(3S/N)均为0.01mg·L^-1。按标准加入法测定了方法的回收率,结果为91.0%~107%,测定值的相对标准偏差(n=6)均小于10%。同一批次内和不同批次间外加标记物的变异系数(CVi)分别为5.8%~8.8%和6.3%~8.4%,说明加香工序的均匀性良好。     

1H NMR determination of hypericin and pseudohypericin in complex natural mixtures by the use of strongly deshielded OH groups

The ¹H NMR spectra of the commercially available compounds hypericin and its derivative pseudohypericin in CD₃OH solutions indicate significantly deshielded signals in the region of 14-15 ppm. These resonances are attributed to the peri hydroxyl protons OH(6), OH(8) and OH(1), OH(13) of hypericins which participate in a strong six-membered ring intramolecular hydrogen bond with CO(7) and CO(14), respectively, and therefore, they are strongly deshielded. In the present work, we demonstrate that one-dimensional ¹H NMR spectra of hypericin and pseudohypericin, in Hypericum perforatum extracts show important differences in the chemical shifts of the hydroxyl groups with excellent resolution in the region of 14-15 ppm. The facile identification and quantification of hypericin and its derivative compound pseudohypericin was achieved, without prior HPLC separation, for two H. perforatum extracts from Greek cultivars and two commercial extracts: a dietary supplement, and an antidepressant medicine. The results were compared with those obtained from UV-vis and LC/MS measurements.     

Use of GC-MS and mass fragmentography for detection, identification and quantitaton of secreted steroids by the human ovary perfused in vitro

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Use of GC-MS and mass fragmentography for detection, identification and quantitaton of secreted steroids by the human ovary perfused in vitro

     

Structural analysis of A-type or B-type highly polymeric proanthocyanidins by thiolytic degradation and the implication in their inhibitory effects on pancreatic lipase

Compared with oligomeric proanthocyanidins, highly polymeric proanthocyanidins have more difficulty to analyze the molecular sizes and the mode of interflavan linkages of flavan-3-ol units through doubly linked A-type bonds and single B-type bonds. Recently, we have shown that seed shells of the Japanese horse chestnut contain highly polymeric proanthocyanidins as dominant polyphenolics that can be separated into two fractions according to the difference in the molecular sizes. Here, we tried to perform the structural characterization of them in terms of the molecular sizes and the proportions of A-type linkages relative to B-type linkages. The results were compared with those of the corresponding preparations with variations in the sizes from fruits of blueberry and cranberry. Gel permeation chromatography revealed that the molecular sizes of them were higher in the order of blueberry > cranberry > seed shells of the Japanese horse chestnut when they are compared between the respective fractions. For the analysis of terminal and extension units of those proanthocyanidins, the isolated fractions were subjected to the thiolytic cleavage of the B-type linkages using 1-dodecanethiol, and the resulting degradation products were identified by ultra-performance liquid chromatography electrospray-ionization mass spectrometry (UPLC-ESI/MS). These analyses provided fast and good resolution of the degradation products and revealed higher proportions of A-type linkages compared with B-type linkages in the both isolated fractions in the order of the seed shells > cranberry > blueberry. Moreover, the isolated fractions with higher molecular sizes and those more abundant in the proportions of A-type linkages were found to be more effective in the inhibition of pancreatic lipase activity. The results suggest that higher molecular sizes and more abundance of A-type bonds in polymeric proanthocyanidins are promising key factors for the attenuation of lipid digestion as dietary supplements.     

Some theoretical and practical aspects in the separation of humic substances by combined liquid chromatography methods

Permanent need to understand nature, structure and properties of humic substances influences also separation methods that are in a wide scope used for fractionation, characterization and analysis of humic substances (HS). At the first glance techniques based on size-exclusion phenomena are the most useful and utilized for relating elution data to the molecular mass distribution of HS, however, with some limitations and exceptions, respectively, in the structural investigation of HS. The second most abundant separation mechanism is reversed-phase based on weak hydrophobic interactions beneficially combined with the step gradients inducing distinct features in rather featureless analytical signal of HS. Relatively great effort is invested to the developments of immobilized-metal affinity chromatography mimicking chelate-forming properties of HS as ligands in the environment. Surprisingly, relatively less attention is given to the ion-ion interactions based ion-exchange chromatography of HS. Chromatographic separation methods play also an important role in the examination of interactions of HS with pesticides. They allow us to determine binding constants and the other data necessary to predict the mobility of chemical pollutants in the environment. HS is frequently adversely acting in analytical procedures as interfering substance, so more detailed information is desired on manifestation of its numerous properties in analytical procedures. The article topic is covered by the review emphasizing advances in the field done in the period of last 10 years from 2000 till 2010.