Phytochemical research using accelerator mass spectrometry

Vegetables and fruits provide an array of microchemicals in the form of vitamins and secondary metabolites (phytochemicals) that may lower the risk of chronic disease. Tracing these phytochemicals at physiologic concentrations has been hindered by a lack of quantitative sensitivity for chemically equivalent tracers that could be used safely in healthy people. Accelerator mass spectrometry is a relatively new technique that provides the necessary sensitivity (in attomoles) and measurement precision (<3%) towards 14C-labeled phytochemicals for detailed kinetic studies in humans at dietary levels.     

Simultaneous analysis of termiticides in indoor air by using gas chromatography mass spectrometry

We have established a method for simultaneously analyzing termiticides (13 kinds) in indoor air based on collection by combination of quartz filter and C18 Empore extraction disks, and measurement using gas chromatography mass spectrometry (GC/MS). The lower limit of determination for each substance was 0.02 microg/m3 when 2 m3 of air was sampled. The recovery was 66-100%, and the relative standard deviation was 3.7-14.2%. In experiments using a model box with commercial termiticides, we verified that emissions of bis (2, 3, 3, 3-tetrachloropropyl) ether (S421) increased with a rise in temperature from 10 degrees C to 20 degrees C to 40 degrees C, whereas almost no etofenprox was released into the air regardless of temperature. In addition, decanal, nonanal and alkanes (C13 and C14), which are major components of termiticides, were detected in relatively high concentrations. In the present study, regardless of low vapor pressure of the termiticides, several compounds were detected with the model box experiment. The conclusion that can be drawn is that it is necessary to survey the indoor environmental pollution.     

沙门菌MALDI-TOF-MS标准菌库的建立及应用研究

目的利用基质辅助激光解析电离飞行时间质谱(MALDI-TOF-MS)构建标准沙门菌株数据库。方法利用MALDI-TOF-MS对21株标准沙门菌进行质谱数据采集,建立标准菌株数据库。相关菌株质谱数据通过菌株在相同培养环境不同培养时间下所得质谱数据进行优化。通过血清型鉴定方法筛选出200株野生沙门菌,并利用自建数据库和现有数据库对200株野生沙门菌进行MALDI-TOF-MS检测,对自建数据库进行评价。结果 Bruker原有数据库、自建数据库及合并数据库对200株野生沙门菌鉴定,阳性率分别为87.5%、97.0%、97.5%。21株标准沙门菌株数据库按亲缘关系远近可分为3大类。主成分分析发现不同菌种之间质谱数据有一定的差异,个别菌种在不同培养条件下培养,质谱数据变化不明显。结论本研究建立的标准菌库对野生沙门菌的鉴定准确性高,适用于实际检测。研究结果丰富了已有的数据库,同时也为其他细菌菌库的建立提供了很好的借鉴。     

高效液相色谱-质谱/质谱联用法检测尿中草甘膦和草铵膦

采用高效液相色谱-质谱/质谱联用仪建立一种简便、灵敏、准确检测尿中草甘膦和草铵膦的方法。样品经初始流动相[0.9%甲酸水溶液︰0.9%甲酸乙腈溶液 (v︰v)=90︰10]萃取和梯度洗脱,于Waters Anionic Polar Pesticide色谱柱上分离, 采用电喷雾负离子化模式、多反应监测的质谱检测。结果显示,经标准工作曲线法定量,方法线性范围10~300 ng/ml,草甘膦、草铵膦检出限分别为3.0、0.8 ng/ml。该方法可以满足草甘膦和草铵膦中毒患者尿液定量检测的要求。     

Laser mass spectrometric analysis of biomedical samples using basic and second harmonics of yttrium-aluminum-garnet laser

Laser mass spectrometric analysis of a biomedical sample was made on exposure to laser radiation at lambda 2 = 532 nm. The parameters of laser radiation and mass spectra were comparatively analyzed by using the basic and second harmonics of aluminum-yttrium-garnet-based laser. The sensitivity of laser mass spectrometry of biomedical samples is increased.     

利用UPLC/Q-TOF MSMS对孤独症患儿血清的代谢组学分析

目的 对孤独症和正常儿童进行血清代谢组学分析,找出特异性代谢产物,为孤独症的早期筛查诊断提供实验依据。方法 采用超高效液相色谱与四级杆飞行时间串联质谱仪联用技术(UPLC/Q-TOF MSMS)和模式识别方法,对孤独症儿童(n=73)和正常对照儿童(n=63)的血清进行代谢组学分析,找出与孤独症相关的特异性代谢产物。 结果 主成分分析得分图显示孤独症组和对照组形成明显的分类,说明孤独症血清代谢谱发生了明显改变,在正离子模式和负离子模式下共鉴定出14个潜在生物标志物。孤独症组的鞘脂类和溶血磷脂类物质明显增多,而多元不饱和脂肪酸(PUFAs)和脂酰肉毒碱明显减少。 结论 孤独症患儿和正常对照组在血清代谢水平上存在明显差异。此发现为找出孤独症诊断的潜在标志物提供了新的依据,并为孤独症的干预提供新的靶点。     

电感耦合等离子体质谱法与液体激光荧光法分析水中铀的比较

目的 建立微波消解、电感耦合等离子体质谱（ICP-MS）测定水中铀的方法,并与液体激光荧光法进行比较。方法 应用建立的微波消解、电感耦合等离子体质谱法（ICP-MS）和液体激光荧光法分别测定不同水样中的铀含量。结果 液体激光荧光法和ICP-MS法的检出限分别为0.021 μg·L^-1和0.003 μg·L^-1,测定结果的标准偏差范围分别为1.20%~4.24%和0.78%~3.46%,精密度分别为3.02%和0.71%,采用两种方法对实际样品进行分析,结果吻合。结论 ICP-MS测量水中铀的检出限低,精密度和准确度更高,但仪器昂贵,测量成本高,因此每个实验室要根据实际条件及样品含铀量大小选择分析方法。     

液相色谱-质谱/质谱联用技术分析18种游离氨基酸

目的：建立氨基酸的液相色谱-质谱检测方法。方法：无需衍生处理，直接用乙腈：水：甲酸（5：95：0．1．v／v／v）为流动相进行反相液相色谱分离，用电喷雾正离子源进行离子化，选择反应监测方式（SRM）对这18种氨基酸的母离子及子离子进行监测，三级四极质谱测定。结果：该方法抗干扰能力强，方法重现性好，RSD0．4％。3．7％，回收率95％～104％，相关系数0．9931-0．9999，检出限0．5～8mol／ml。结论：该方法简单、快速、准确、灵敏，适合测定各种样品中的游离氨基酸。     

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry for bacterial strain characterization

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged as a new technique for rapid and effective bacterial species identification in clinical microbiology laboratories. Conventional bacterial identification is based essentially on biochemical tests and requires lengthy incubation procedures. By contrast, MALDI-TOF MS can identify bacterial species in a few minutes, directly from a freshly grown colony. Various approaches have been developed for bacterial identification and the efficacy of this method has been demonstrated in several studies. This technique should also be suitable for the classification of organisms to subspecies level and for the phenotypic detection of certain antibiotic resistance mechanisms, such as β-lactamases production.     

应用飞行时间质谱仪快速鉴定细菌的初步研究

目的　研究基质辅助激光解析电离飞行时间质谱对细菌快速鉴定的影响因素。方法　应用 8种细菌 ,比较了不同培养基 (哥伦比亚血琼脂、伊红美兰琼脂、普通营养琼脂 )及培养时间对细菌质谱图的影响。结果　不同的培养基及培养时间会对细菌质谱图产生影响。结论　选择合适的培养基及培养时间可以提高细菌检测的准确率     

Differentiation of Campylobacter species by surface-enhanced laser desorption/ionization-time-of-flight mass spectrometry

The genus Campylobacter contains several, widespread pathogens causing food-borne diseases of zoonotic nature in humans. In case of outbreaks, the differentiation of closely related Campylobacter is essential for epidemiological studies, which investigate the routes of geographical spread and ways of transmission. Recent advances in mass spectrometry (MS) have shown that matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) MS is a valuable tool for speciation of bacteria such as Campylobacter. Surface-enhanced laser desorption/ionization (SELDI)-TOF-MS is a specific MALDI-TOF application that combines a chip-based chromatographic enrichment of proteins with TOF-MS. This pilot study aims at investigating for the first time whether SELDI-TOF-MS can be applied for discrimination of Campylobacter at the level of species and even strains. Campylobacter type-strains and isolates from different regions were cultured and subsequently subjected to physicochemical lysis. Protein lysates were then applied on CM10 and IMAC30 ProteinChip Array surfaces and analyzed using a PCS 4000 SELDI Protein Chip System (Bio-Rad Laboratories). By comparison of the spectra from Campylobacter jejuni, Campylobacter coli, Campylobacter upsaliensis, and Campylobacter lari, 166 and 160 different protein peaks were observed (p<0.05) using CM10 and IMAC30 chips, respectively. Development of classification trees, comprising 2-4 of these peaks, allows for discrimination of different Campylobacter species and even strains. Moreover, species and strains can be sufficiently separated from each other by hierarchical cluster analysis. Thus, SELDI-TOF-MS is a promising tool to differentiate Campylobacter species and even strains. Species/strain-specific ions observed in addition to well-established markers identified by MALDI-TOF might be of value for future Campylobacter-identifying algorithms. To further clarify the potential advantages of this method, our results have to be validated against several independent test datasets of, preferably, a multitude of prospectively collected different isolates and compared with other typing techniques.     

城市污水处理厂污泥中磺胺类抗生素的液相色谱-串联质谱法测定

目的建立城市污水处理厂污泥中20种磺胺类抗生素的液相色谱-串联质谱分析方法。方法比较超声萃取(USE)和加速溶剂萃取(ASE)对污泥中目标药物的提取效率,优化了富集净化过程。样品经USE提取,MAX固相萃取柱净化,用液相色谱-电喷雾串联质谱法(LC-ESI-MS/MS)检测。C18柱分离,正离子多反应监测模式检测,内标法定量。结果方法定量限为0.25～10.0μg/kg;三个加标水平的回收率为50.1%～120.0%,相对标准偏差小于30%。应用此方法在北京某污水处理厂活性污泥和剩余污泥中检出磺胺嘧啶、磺胺吡啶和磺胺甲恶唑,含量为2.1～153.1μg/kg。结论该方法适用于污泥中20种磺胺类抗生素的同时检测。     

Analysis of Bacillus anthracis spores in milk using mass spectrometry

New approaches for identifying biological threat agents in raw milk using spectroscopy were tested using Bacillus anthracis (BA) Sterne strain spores seeded into unpasteurized bulk tank milk. Direct filtration onto Tyvek membranes provided the optimal filtration approach from raw milk, but detection limits were not ideal. When beads coated with anti-BA antibodies were mixed with spores in raw milk, the beads were capable of concentrating the spores that could be later detected and characterized by MALDI spectroscopy based on presence of previously characterized small acid-soluble proteins (SASP's). This approach could provide a very rapid assessment of whether milk or milk products have been purposefully contaminated with BA spores. This work was fundamentally a proof-of-concept study demonstrating feasibility of the approach in milk. Other parameters could be changed to potentially lower detection limits, and additional studies are currently underway to improve the approach.     

Rapid identification and analysis of airborne plutonium using a combination of alpha spectroscopy and inductively coupled plasma mass spectrometry

Recent wildland fires near two U.S. nuclear facilities point to a need to rapidly identify the presence of airborne plutonium during incidents involving the potential release of radioactive materials. Laboratory turn-around times also need to be shortened for critical samples collected in the earliest stages of radiological emergencies. This note discusses preliminary investigations designed to address both these problems. The methods under review are same day high-resolution alpha spectroscopy to screen air filter samples for the presence of plutonium and inductively coupled plasma mass spectrometry to perform sensitive plutonium analyses. Thus far, using modified alpha spectroscopy techniques, it has been possible to reliably identify the approximately 5.2 MeV emission of 239Pu on surrogate samples (air filters artificially spiked with plutonium after collection) even though the primary alpha-particle emissions of plutonium are, as expected, superimposed against a natural alpha radiation background dominated by short-lived radon and thoron progeny (approximately 6-9 MeV). Several processing methods were tested to prepare samples for analysis and shorten laboratory turn-around time. The most promising technique was acid-leaching of air filter samples using a commercial open-vessel microwave digestion system. Samples prepared in this way were analyzed by both alpha spectroscopy (as a thin-layer iron hydroxide co-precipitate) and inductively coupled plasma mass spectrometry. The detection levels achieved for 239Pu--approximately 1 mBq m(-3) for alpha spectroscopy screening, and, < 0.1 mBq m(-3) for inductively coupled plasma mass spectrometry analysis--are consistent with derived emergency response levels based on EPA's Protective Action Guides, and samples can be evaluated in 36 to 72 h. Further, if samples can be returned to a fixed-laboratory and processed immediately, results from mass spectrometry could be available in as little as 24 h. When fully implemented, these techniques have the potential to provide useful information and improved operational flexibility to emergency planners and first-responders during radiological emergencies.     

Ultra-trace analysis of multiple endocrine-disrupting chemicals in municipal and bleached kraft mill effluents using gas chromatography-high-resolution mass spectrometry

A comprehensive gas chromatographic-high-resolution mass spectrometric (GC-HRMS)-based method was developed that permitted the simultaneous determination of 30 estrogenic endocrine-disrupting chemicals (EDCs) and related compounds, including surfactants, biogenic and synthetic steroids, fecal sterols, phytoestrogens, and plasticizers, in wastewater. Features of the method include low sample volume (~40 ml), optimized Florisil cleanup to minimize matrix interferences and optimized analyte derivatization to improve sensitivity via GC-HRMS. Detection limits were in the low- to mid-ng/L range, and recoveries were greater than 60% for most target analytes. This new method allows for high throughput analysis of many organic wastewater contaminants in a complex matrix with relative standard deviation of less than 15% for most measurable compounds. The applicability of the method was demonstrated by examining wastewater samples from different origins. Compounds such as di(2-ethylhexyl)phthalate, cholesterol, cholestanol, and other cholesterol derivatives were measured in much higher concentrations in untreated sewage and were reduced substantially in concentration by the treatment process. However, steroidal compounds, particularly estrone (E1), 17beta-estradiol (E2), and estriol (E3), as well as plant sterols (except stigmastanol), were greater in the treated municipal wastewater versus the untreated effluent. Plant and fungi sterols, stigmastanol and ergosterol, were found largely associated with bleached kraft mill effluent (BKME) as compared to the municipal effluents.     

通过基质辅助激光解析电离飞行时间质谱系统直接快速鉴定阳性血培养

目的基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)在临床微生物实验室的应用,为阳性血培养中微生物鉴定提供了革命性的新方法,我们报告一种改良的利用MALDI-TOF质谱直接鉴定阳性血培养的方法。方法 2011年10月-2012年10月共收集312瓶阳性培养物,细菌分别属于12个不同属和32个种,MALDI-TOF质谱鉴定的细菌同时进行了常规生化法鉴定,其中不符合的部分通过序列分型明确。结果 200株革兰阳性菌中,161株(80.5%)准确鉴定到属以上水平,121株(60.5%)准确鉴定到种;112株革兰阴性菌中,101株(90.2%)准确鉴定到属以上水平,81株(72.3%)准确鉴定到种水平;MALDI-TOF质谱鉴定革兰阴性菌,在属以上水平和种水平上,准确率均高于革兰阳性菌。结论通过这种方法能在1h内快速、鉴定阳性血培养中的常见细菌,如果将此项技术常规应用于临床,将显著增加菌血症患者在24h内得到最佳抗菌药物治疗的比例。