芳香硝基化合物的能量分辨质谱

本文报道用ＭＳ／ＭＳ技术的一种重要实验方法——能量分辨质谱（ＥＲＭＳ）来鉴别质谱分析中的同分异构体化合物。系统探讨了同分异构的硝基芳香化合物２，３－ＤＮＴ和３，５－ＤＮＴ（相对分子质量为１８２）在电子轰击（ＥＩ）方式下，裂分途径与其分子内能的相互关系以及离子的结构和裂分途径相对于碰撞能量（ＣＥ）的依赖关系（裂分曲线）。结果表明，利用同分异构化合物在能量分辨中的显著差异可以辨别它们的结构     

Nitrogen and hydrogen as carrier and make-up gases for GC-MS with Cold EI

Gas chromatography–mass spectrometry (GC-MS) with Cold EI is based on interfacing GC and MS with a supersonic molecular beam (SMB) and sample compounds ionization with a fly-through ion source as vibrationally cold compounds in the SMB (hence the name Cold EI). We explored the use of nitrogen and hydrogen as carrier and make-up gases with Cold EI and found:

1. Nitrogen is very effective in cooling compounds in SMB and while helium requires 60 ml/min nitrogen provides effective cooling with only 7–8 ml/min combined column and make-up flow rate. Hydrogen is less effective than helium and requires higher flow rates.
2. The transition from helium to nitrogen (or hydrogen) is simple and fast and requires just closing the helium valve and opening the nitrogen valve.
3. The same column used with helium can be used with nitrogen or hydrogen.
4. The same elution times could be obtained with nitrogen or hydrogen as with helium.
5. The GC separation with nitrogen was reduced compared with helium and peak widths were increased by an average factor of 1.5 for similar elution times. Hydrogen provided ~0.7 narrower peak widths than helium.
6. The signal with nitrogen was reduced compared with helium by an average factor of 3.3 and the signal loss was reduced with higher compounds mass. With hydrogen the signal loss was about a factor of 1.5 but the baseline noise was higher thus with similar S/N as with nitrogen.
7. USEPA 8270 semivolatile mixture was easily analyzed with both nitrogen and hydrogen carrier gases.

     

环己酮绿色氧化合成己二酸质谱分析

己二酸是合成尼龙-66的主要原料,同时在低温润滑油、合成纤维、油漆、聚亚胺酯树脂及食品添加剂的制备等方面也有重要用途,目前己二酸的世界年产量估计已达220万吨。工业上已二酸的生产是以环己烷经两步氧化合成,第一步为环己烷在金属离子催化下用氧气氧化为环己醇、环己酮,第二步用浓HNO3氧化环己醇、环己酮制得己二酸。在第二步氧化时由于用了浓HNO3故产生大量的CO、NOx、N2O等有毒气体,其中N2O是比CO2还强310倍的温室气体。在当今普遍提倡绿色化学的时代,如何减少化工生产对环境的污染是当前化学工作者首要解决的任务。过氧化氢是一种理想的清洁氧化剂,其反应的唯一预期副产物是水,反应后处理容易,同时过氧化氢的价格相对低廉,氧化成本低。为此,许多化学工作者对环己酮绿色氧化制剂己二酸已有研究。但环己酮氧化为己二酸的反应产物的研究未见报道,本文报道环己酮氧化为己二酸的12种产物。     

Detection of Fungi and Oomycetes by Volatiles Using E-Nose and SPME-GC/MS Platforms

Fungi and oomycetes release volatiles into their environment which could be used for olfactory detection and identification of these organisms by electronic-nose (e-nose). The aim of this study was to survey volatile compound emission using an e-nose device and to identify released molecules through solid phase microextraction–gas chromatography/mass spectrometry (SPME–GC/MS) analysis to ultimately develop a detection system for fungi and fungi-like organisms. To this end, cultures of eight fungi (Armillaria gallica, Armillaria ostoyae, Fusarium avenaceum, Fusarium culmorum, Fusarium oxysporum, Fusarium poae, Rhizoctonia solani, Trichoderma asperellum) and four oomycetes (Phytophthora cactorum, P. cinnamomi, P. plurivora, P. ramorum) were tested with the e-nose system and investigated by means of SPME-GC/MS. Strains of F. poae, R. solani and T. asperellum appeared to be the most odoriferous. All investigated fungal species (except R. solani) produced sesquiterpenes in variable amounts, in contrast to the tested oomycetes strains. Other molecules such as aliphatic hydrocarbons, alcohols, aldehydes, esters and benzene derivatives were found in all samples. The results suggested that the major differences between respective VOC emission ranges of the tested species lie in sesquiterpene production, with fungi emitting some while oomycetes released none or smaller amounts of such molecules. Our e-nose system could discriminate between the odors emitted by P. ramorum, F. poae, T. asperellum and R. solani, which accounted for over 88% of the PCA variance. These preliminary results of fungal and oomycete detection make the e-nose device suitable for further sensor design as a potential tool for forest managers, other plant managers, as well as regulatory agencies such as quarantine services.     

Combining chromatography and chemometrics for the characterization and authentication of fats and oils from triacylglycerol compositional data—A review

The characterization and authentication of fats and oils is a subject of great importance for market and health aspects. Identification and quantification of triacylglycerols in fats and oils can be excellent tools for detecting changes in their composition due to the mixtures of these products. Most of the triacylglycerol species present in either fats or oils could be analyzed and identified by chromatographic methods. However, the natural variability of these samples and the possible presence of adulterants require the application of chemometric pattern recognition methods to facilitate the interpretation of the obtained data. In view of the growing interest in this topic, this paper reviews the literature of the application of exploratory and unsupervised/supervised chemometric methods on chromatographic data, using triacylglycerol composition for the characterization and authentication of several foodstuffs such as olive oil, vegetable oils, animal fats, fish oils, milk and dairy products, cocoa and coffee.     

The tensor product of Gorenstein-projective modules over category algebras

For a finite free and projective EI category, we prove that Gorenstein-projective modules over its category algebra are closed under the tensor product if and only if each morphism in the given category is a monomorphism.     

基于遥感数据的辽宁省植被变化分析

利用从美国国家海洋和大气局(NOAA)的甚高分辨率辐射计(AVHRR)获得的20年的归一化植被指数(NDVI)时序数据,分析了辽宁省的空间异质性和时间动态。通过分析研究区域2 292个点在1982～2001年间NDVI月平均值,发现有明显的反常。通过统计分析每月的NDVI值,包括最小值、平均值、最大值、变化系数(CV)、标准化不规则值(Z分),36个月的动态平均值,识别了植被动态的空间和时间变化。发现植被的NDVI在生长期有强烈的季节摆动,观测到的NDVI最大值出现在7～8月,用CV表达的季节变化范围从6%～14%。另外,在1984～1990年间植被绿度呈现一致向上的趋势,而在随后的1991～1998年间表现出很大的相反。植被绿度向上和向下的趋势遵从7到8年的摆动周期。研究还发现干燥季节NDVI的峰值沿纬度的变化是1991～1999年间比1982～1990年间大20%～25%。研究的结论是辽宁省的植被变化模式是由于20世纪最后10年加剧的干旱造成的。     

微波辅助萃取-气相色谱-负化学电离/电子轰击电离-飞行时间质谱法测定烟草中农药残留

建立了微波辅助萃取结合气相色谱-飞行时间质谱(GC-TOF MS)技术在负化学电离(NCI)源和电子轰击电离(EI)源两种模式下测定烟草中24种农药残留的分析方法。烟叶样品于100℃下用二氯甲烷-正己烷(3:1, v/v)混合溶剂微波萃取10 min,萃取液经弗罗里硅土固相萃取柱净化后进行检测分析。在NCI源和EI源质谱模式下,24种农药的线性关系均良好(r²>0.99),相对标准偏差分别小于8.6%和9.1%,定量限分别为0.3~6.9 μg/kg和10.2~44.9 μg/kg,加标回收率分别为75.2%~94.8%和75.0%~95.1%。比较两种离子源模式下的色谱图和质谱图,NCI源模式较EI源模式的选择性好、灵敏度高、基质干扰小、图谱简单易于解析,检出限低一个数量级以上,在分析低含量、复杂基质的样品时更具优势。     

Simultaneous quantification of tramadol and O‐desmethyltramadol in hair samples by gas chromatography–electron impact/mass spectrometry

Over recent years, hair has become the ideal matrix for retrospective investigation of chronic abuse, including for tramadol. However, in order to exclude the possibility of external contamination, it is also important to quantify simultaneously its main metabolite, O‐desmethyltramadol (M1), which presence in hair reflects systemic exposure. In the present study a methodology aimed at the simultaneous quantification of tramadol and M1 in human hair was developed and validated for the first time. After decontamination of hair samples (60 mg), tramadol and M1 were extracted with methanol in an ultrasonic bath (~5 h). Purification was performed by solid‐phase extraction using mixed‐mode extraction cartridges. Subsequently to derivatization, analysis was performed by gas chromatography–electron impact/mass spectrometry (GC‐EI/MS). The method proved to be selective. The regression analysis for both analytes was shown to be linear in the range of 0.1–20.0 ng/mg with correlation coefficients of 0.9995 and 0.9997 for tramadol and M1, respectively. The coefficients of variation oscillated between 3.85 and 13.24%. The limits of detection were 0.03 and 0.02 ng/mg, and the lower limits of quantification were 0.08 and 0.06 ng/mg for tramadol and M1, respectively. The proof of applicability was performed in hair samples from six patients undergoing tramadol therapy. All samples were positive for tramadol and M1. Copyright © 2013 John Wiley & Sons, Ltd.     

新疆工程技术科学研究研发态势的文献计量分析

对1996—2005年EI新疆工程技术科学论文的分析表明，新疆工程技术科学发展呈现不稳定状态，科学著述指标有待进一步提高，乌鲁木齐和新疆大学是新疆工程技术科学研究的地区和机构问的科学活动中心，新疆的学科分布体现出学科产业的优势与特点．