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1.
Pesticides are toxic substances and may cause unintentional harm if improperly used. The ubiquitous nature of pesticides, with frequent use in agriculture and the household, and the potential for harm that pesticides pose to non-target organisms such as wildlife, humans, and pets, demonstrate the need for rapid and effective detection and identification of these compounds. In this study, single particle aerosol mass spectrometry (SPAMS) was used to rapidly detect compounds from four classes of pesticides commonly used in agricultural and household applications. These include permethrin (pyrethroid class), malathion and dichlorvos (organophosphate class), imidacloprid (chloronicotinyl class), and carbaryl (carbamate class). Analytical standards of each compound were diluted and aerosolized using a nebulizer to create particles for analysis in the SPAMS instrument. The resultant dual-polarity time-of-flight mass spectra were then analyzed to identify the characteristic peaks of the compound in each sample. In addition, samples of commercial products containing pesticides, a commercial insecticide spray, containing permethrin, and a canine flea collar, containing carbaryl, were analyzed in their original form using SPAMS without any significant sample preparation. The characteristic mass spectral peaks of the active pesticides in these samples were identified using the mass spectra obtained earlier from the pesticide analytical standards. By successfully identifying pesticides in analytical standards and in commercial products, it is demonstrated herein that the SPAMS system may be capable of pesticide detection in numerous environmental and agricultural situations.  相似文献   

2.
This review describes recently presented instrumental set-ups for aerosol mass spectrometry (AMS), most being suitable for in-situ analysis. AMS allows the analysis of atmospheric aerosol particles within a short time interval and without sample pretreatment, and it is less sensitive to artifact formation than conventional sampling and analytical techniques. Although a quantitative measure of total organic loading can be obtained with some AMS instruments, they currently give only limited information on specific compounds. When the ionization technique produces a large number of fragments for a compound, it becomes impossible to track the original compound. Moreover, at present, there is no commercially available instrument capable of quantitative analysis of chemical compounds in ambient aerosol particles with diameters of 0.003–50 μm and simultaneously offering short time resolution. We pay special attention to the technical and methodological challenges of AMS, whose benefits we demonstrate with selected applications.  相似文献   

3.
表面解吸常压化学电离源的研制及应用   总被引:10,自引:0,他引:10  
根据表面解吸常压化学电离源(SDAPCI)对表面痕量待测物进行常压解吸化学电离的原理,自行研制了SDAPCI电离源及其与线性离子阱(LTQ)质谱仪的接口,成功地在LTQ上实现了表面解吸常压化学电离。此方法无需样品预处理,直接利用电晕放电产生的H3O 在常压下对待测样品进行表面解吸化学电离,避免了甲醇等有毒试剂的使用。在优化的仪器参数条件下,分别用正/负离子模式成功地检测了片剂药品中的氯雷他定、乙酰氨基酚等活性成分和其它不同表面上TNT、氨基酸和多肽等物质,对这些常见物质的检出限不高于10pg/cm2。采用氩气作为电离试剂,观测到乙酰氨基酚、多肽等物质形成的自由基阳离子,提出了在氩气氛围中获得自由基阳离子的可能机理。实验表明SDAPCI具有灵敏度较高,选择性好,适用范围宽等特点,适合用于药品、食品等非破坏、无污染检测以及对复杂基体物质进行快速现场分析。  相似文献   

4.
5.
Matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) time-of-flight mass spectrometry (TOFMS) play an essential role in the analysis of biological molecules, not only peptides and proteins, but also DNA and RNA. Tandem mass spectrometry used for sequence analysis has been a major focus of technological developments in mass spectrometry, but accurate mass measurements by high-resolution TOFMS are equally important. This paper describes the role that high mass measurement accuracy can play in DNA composition assignment and discusses the influence of several parameters on mass measurement accuracy in both MALDI and ESI mass spectra. Five oligonucleotides (5-13mers) were used to test the resolving power and mass measurement accuracy obtained with MALDI and ESI instruments with reflectron TOF mass analyzers. The results from the experimental studies and additional theoretical calculations provide a basis to predict the practical utility of high-resolution TOFMS for the analysis of larger oligonucleotides.  相似文献   

6.
A rapid and sensitive LC-MS/MS method was developed for the quantitative determination of sucrose esters (SEs) in Oriental tobacco samples. The sample preparation involved a 10-min sonication extraction procedure with acetone and five-fold dilution of the extract with methanol. The experiment was carried out in positive ion mode by ESI IT mass spectrometer. Because of lack of authentic standards of SEs, sucrose octa-acetate (internal standard, IS) was used as a surrogate to validate the proposed method. Matrix-matched standard calibration was used for quantification of IS in the spiked samples. Under optimized MS/MS conditions, an LOQ of 3.9 microg/g was achieved for IS, with an LOD of about 1.2 microg/g. Recoveries for IS were 95-97%. Among 19 monitored SEs, the contents of 11 SEs had RSDs lower than 13.7%. The method, with very little sample handling and good sensitivity, was applied to the rapid quantification of SEs in four Oriental tobacco samples. It appears that the sum of contents of the five SEs with MW 650, 664, and 678 Da occupied approximately 80% of the total content of SEs.  相似文献   

7.
Capillary electrophoresis (CE) offers fast and high‐resolution separation of charged analytes from small injection volumes. Coupled to mass spectrometry (MS), it represents a powerful analytical technique providing (exact) mass information and enables molecular characterization based on fragmentation. Although hyphenation of CE and MS is not straightforward, much emphasis has been placed on enabling efficient ionization and user‐friendly coupling. Though several interfaces are now commercially available, research on more efficient and robust interfacing with nano‐electrospray ionization (ESI), matrix‐assisted laser desorption/ionization (MALDI) and inductively coupled plasma mass spectrometry (ICP) continues with considerable results. At the same time, CE‐MS has been used in many fields, predominantly for the analysis of proteins, peptides and metabolites. This review belongs to a series of regularly published articles, summarizing 248 articles covering the time between June 2016 and May 2018. Latest developments on hyphenation of CE with MS as well as instrumental developments such as two‐dimensional separation systems with MS detection are mentioned. Furthermore, applications of various CE‐modes including capillary zone electrophoresis (CZE), nonaqueous capillary electrophoresis (NACE), capillary gel electrophoresis (CGE) and capillary isoelectric focusing (CIEF) coupled to MS in biological, pharmaceutical and environmental research are summarized.  相似文献   

8.
Negative-ion atmospheric pressure chemical ionization (APCI) mass spectrometry and in-source collisionally induced dissociation (CID) were employed to obtain structural information of lutein esters from marigold extract. Both molecular ions and structurally significant fragments corresponding to the loss of fatty acids were observed in high abundance in the current study. Six lutein diesters including lauroylmyristoyl-lutein (LML), dimyristoyl-lutein (dML), myristoylpalmitoyl-lutein (MPL), dipalmitoyl-lutein (dPL), palmitoylstearoyl-lutein (PSL) and distearoyl-lutein (dSL) were characterized in a marigold flower extract. Breakdown curves (plots of relative ion abundance vs. internal energy) of three lutein diesters were established by monitoring the relative ion abundance of molecular and fragment ions at different cone voltages during negative-ion APCI-LC/MS analysis.  相似文献   

9.
A new solid phase extraction (SPE) method coupled to a high throughput sample analysis technique was developed for the simultaneous determination of nine selected emerging contaminants in wastewater (atrazine, desethylatrazine, 17β-estradiol, ethynylestradiol, norethindrone, caffeine, carbamazepine, diclofenac and sulfamethoxazole). We specifically included pharmaceutical compounds from multiple therapeutic classes, as well as pesticides. Sample pre-concentration and clean-up was performed using a mixed-mode SPE cartridge (Strata ABW) having both cation and anion exchange properties, followed by analysis by laser diode thermal desorption atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS). The LDTD interface is a new high-throughput sample introduction method, which reduces total analysis time to less than 15 s per sample as compared to minutes with traditional liquid-chromatography coupled to tandem mass spectrometry (LC–MS/MS). Several SPE parameters were evaluated in order to optimize recovery efficiencies when extracting analytes from wastewater, such as the nature of the stationary phase, the loading flow rate, the extraction pH, the volume and composition of the washing solution and the initial sample volume. The method was successfully applied to real wastewater samples from the primary sedimentation tank of a municipal wastewater treatment plant. Recoveries of target compounds from wastewater ranged from 78% to 106%, the limit of detection ranged from 30 to 122 ng L−1 while the limit of quantification ranged from 90 to 370 ng L−1. Calibration curves in the wastewater matrix showed good linearity (R2 ≥ 0.991) for all target analytes and the intraday and interday coefficient of variation was below 15%, reflecting a good precision.  相似文献   

10.
A sturdy home-built sheathless CE/ESI-QTOF-MS system was developed and optimized for carbohydrate analysis. The interface and employed methodology provided a simple analytical solution to laborious CE/MS interfacing methods and to problems in characterization of complex carbohydrate mixtures that require high-resolution separation of the components. The CE/ESI interface, feasible in any MS laboratory, consists of a one-piece CE column having the CE terminus in-laboratory shaped as a microsprayer and coated with copper. The CE microsprayer was inserted into an in-house made stainless steel clenching device and the whole assembly was mounted onto a quadrupole TOF mass spectrometer. The analytical potential of the interface in terms of suitability, microsprayer performance, copper coat durability, ionization efficiency, spray stability, and sensitivity was tested first on a simple mixture of standard saccharides, which were separated, resolved, and detected with high separation efficiency. The approach was next assessed for the screening of a biological sample, a complex mixture of O-glycosylated sialylated amino acids from urine of a patient suffering from Schindler disease. Preliminary data allow this method to be considered as one of general applicability in structural glycobiology and glycomics and easy to be implemented for proteomic surveys as well.  相似文献   

11.
Accurate isotope ratio measurements are of high importance in various scientific fields, ranging from radio isotope geochronology of solids to studies of element isotopes fractionated by living organisms. Instrument limitations, such as unresolved isobaric inferences in the mass spectra, or cosampling of the material of interest together with the matrix material may reduce the quality of isotope measurements. Here, we describe a method for accurate isotope ratio measurements using our laser ablation ionization time‐of‐flight mass spectrometer (LIMS) that is designed for in situ planetary research. The method is based on chemical depth profiling that allows for identifying micrometer scale inclusions embedded in surrounding rocks with different composition inside the bulk of the sample. The data used for precise isotope measurements are improved using a spectrum cleaning procedure that ensures removal of low quality spectra. Furthermore, correlation of isotopes of an element is used to identify and reject the data points that, for example, do not belong to the species of interest. The measurements were conducted using IR femtosecond laser irradiation focused on the sample surface to a spot size of ~12 μm. Material removal was conducted for a predefined number of laser shots, and time‐of‐flight mass spectra were recorded for each of the ablated layers. Measurements were conducted on NIST SRM 986 Ni isotope standard, trevorite mineral, and micrometer‐sized inclusions embedded in aragonite. Our measurements demonstrate that element isotope ratios can be measured with accuracies and precision at the permille level, exemplified by the analysis of B, Mg, and Ni element isotopes. The method applied will be used for in situ investigation of samples on planetary surfaces, for accurate quantification of element fractionation induced by, for example, past or present life or by geochemical processes.  相似文献   

12.
13.
The applicability of liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the detection of the free anabolic steroid fraction in human urine was examined. Electrospray ionization (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization methods were optimized regarding eluent composition, ion source parameters and fragmentation. The methods were compared with respect to specificity and detection limit. Although all methods proved suitable, LC/ESI-MS/MS with a methanol-water gradient including 5 mM ammonium acetate and 0.01% acetic acid was found best for the purpose. Multiple reaction monitoring allowed the determination of steroids in urine at low nanogram per milliliter levels. LC/MS/MS exhibited high sensitivity and specificity for the detection of free steroids and may be a suitable technique for screening for the abuse of anabolic steroids in sports.  相似文献   

14.
Molecular images of documents were obtained by sequentially scanning the surface of the document using desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI‐MS), which was operated in either a gasless, solvent‐free or methanol vapor‐assisted mode. The decay process of the ink used for handwriting was monitored by following the signal intensities recorded by DAPCI‐MS. Handwritings made using four types of inks on four kinds of paper surfaces were tested. By studying the dynamic decay of the inks, DAPCI‐MS imaging differentiated a 10‐min old from two 4 h old samples. Non‐destructive forensic analysis of forged signatures either handwritten or computer‐assisted was achieved according to the difference of the contour in DAPCI images, which was attributed to the strength personalized by different writers. Distinction of the order of writing/stamping on documents and detection of illegal printings were accomplished with a spatial resolution of about 140 µm. A Matlab® written program was developed to facilitate the visualization of the similarity between signature images obtained by DAPCI‐MS. The experimental results show that DAPCI‐MS imaging provides rich information at the molecular level and thus can be used for the reliable document analysis in forensic applications. © 2013 The Authors. Journal of Mass Spectrometry published by John Wiley & Sons, Ltd.  相似文献   

15.
Several positional isomers of 2-(2-quinolinyl)-1H-indene-1,3(2H)-dione mono- and disulfonic acids prepared as reference materials for development of analytical methods involved in FDA certification of D&C Yellow No. 10 (Quinoline Yellow) were found consistently to show [MH + 14](+) ions when their electrospray- or atmospheric pressure chemical ionization-prepared MH(+) ions were subjected to collisional activation. The source of these ions was found to be the methanol used as solvent in these procedures which combined with their [MH - H(2)O](+) ions under chemical ionization conditions. The reaction was found to be sensitive to their isomeric and chemical structures and other examples of this process are reviewed.  相似文献   

16.
王昊阳  郭寅龙 《中国科学:化学》2014,(5):39-41,690,693
有机化学反应中活性中间体的性质各异,对反应中间体的表征和研究对于阐明和确证反应机理、优化反应条件、筛选催化剂和发现新类型反应至关重要.近年来,质谱技术和在线微量采样技术的发展,极大程度地拓展了质谱学在该领域的应用.本文总结了近年来本领域发展的新策略、技术和方法,以及有机质谱技术在反应中间体研究中的应用.  相似文献   

17.
宋春侠  刘颖荣  刘泽龙  王威  田松柏 《色谱》2015,33(5):488-493
随着原油重质化、劣质化程度的加深以及环境保护对燃油清洁性要求的日趋严格,对石油组成进行分子水平详细表征具有重大的现实意义和经济价值。依赖于高分辨质谱技术平台的石油组学分析技术成为实现这一目标的有力工具。本文以高分辨质谱技术平台为切入点,对石油组学定性定量分析技术的最新进展进行回顾和总结,并对其发展前景进行展望。  相似文献   

18.
A novel approach to the analysis of ecstasy tablets by direct mass spectrometry coupled with thermal desorption (TD) and counter‐flow introduction atmospheric pressure chemical ionization (CFI‐APCI) is described. Analytes were thermally desorbed with a metal block heater and introduced to a CFI‐APCI source with ambient air by a diaphragm pump. Water in the air was sufficient to act as the reactive reagent responsible for the generation of ions in the positive corona discharge. TD‐CFI‐APCI required neither a nebulizing gas nor solvent flow and the accompanying laborious optimizations. Ions generated were sent in the direction opposite to the air flow by an electric field and introduced into an ion trap mass spectrometer. The major ions corresponding to the protonated molecules ([M + H]+) were observed with several fragment ions in full scan mass spectrometry (MS) mode. Collision‐induced dissociation of protonated molecules gave characteristic product‐ion mass spectra and provided identification of the analytes within 5 s. The method required neither sample pretreatment nor a chromatographic separation step. The effectiveness of the combination of TD and CFI‐APCI was demonstrated by application to the direct mass spectrometric analysis of ecstasy tablets and legal pharmaceutical products. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

19.
Clinically obtained human kidney stones of different pathogenesis were dissolved in acetic acid/methanol solutions and then rapidly analyzed by surface desorption atmospheric pressure chemical ionization mass spectrometry (SDAPCI-MS) without any desalination treatment. The mass spectral fingerprints of six groups of kidney stone samples were rapidly recorded in the mass range of m/z 50-400. A set of ten melamine-induced kidney stone samples and nine uric acid derived kidney stone samples were successfully differentiated from other groups by principal component analysis of SDAPCI-MS fingerprints upon positive-ion detection mode. In contrast, the mass spectra recorded using negative-ion detection mode did not give enough information to differentiate those stone samples. The results showed that in addition to the melamine, the chemical compounds enwrapped in the melamine-induced kidney stone samples differed from other kidney stone samples, providing useful hints for studying on the formation mechanisms of melamine-induced kidney stones. This study also provides useful information on establishing a MS-based platform for rapid analysis of the melamine-induced human kidney stones at molecular levels.  相似文献   

20.
Wang X  Qin W  Qian X  Zhang Y 《色谱》2012,30(3):239-244
建立了氨基酸同位素稀释液相色谱-串联质谱法准确测定合成肽段绝对含量的方法。实验中对合成肽段的纯度进行了表征,色谱纯度表征结果为99%以上,质谱纯度为90%以上。在肽段溶液中加入13C标记的氨基酸后进行酸溶液水解时间的优化,水解后的氨基酸直接经液相色谱分离和质谱检测,结果表明肽段中的被测氨基酸在150 ℃、6 mol/L HCl溶液水解4~6 h就可以达到水解平衡。每个肽段选择两个或两个以上的被测氨基酸,测得随机选择的5种合成肽段的绝对含量为62.07%~88.18%,测定结果的相对标准偏差小于8%,相对误差小于5%,均满足定量要求。除常用的被测氨基酸苯丙氨酸、缬氨酸、异亮氨酸外,还考察了选择赖氨酸和精氨酸作为被测氨基酸的可行性,实验结果表明增加精氨酸为被测氨基酸是可行的,从而进一步增加了方法的普适性。该方法的建立避免了色谱法定量时氨基酸衍生化处理带来的副反应影响及操作繁琐等问题,提高了肽段含量测定的准确度和精密度,为肽段含量的准确测定提供了一种新的方法。  相似文献   

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