气相色谱-质谱法测定纺织品中喹啉与异喹啉

建立了纺织品中喹啉和异喹啉的气相色谱-质谱检测方法。采用乙酸乙酯为溶剂,超声提取,经蒸发浓缩和定容后,以GC-MS测定。结果表明,喹啉和异喹啉在0.05～10.0 mg/L范围内线性良好(r>0.999 0),回收率为82.0%～99.8%,相对标准偏差(n=6)为0.9%～3.8%;方法的定量下限为0.05 mg/kg。该方法灵敏度高、简便、高效、准确,可以满足纺织品中喹啉和异喹啉的检测需求。     

衍生-分散液相微萃取/气相色谱-质谱法测定纺织品中的含氯酚及邻苯基苯酚

建立了衍生、分散液相微萃取(DLLME)与气相色谱-质谱(GC-MS)联用测定纺织品中5种含氯酚(PCPs)和邻苯基苯酚(OPP)的方法。对影响萃取和富集效率的因素,萃取剂种类及用量、分散剂种类及用量、碳酸钾溶液浓度等条件进行了优化。确定最佳实验条件为:纺织样品用0.15 mol/L的碳酸钾溶液超声提取后定容,取5 mL溶液,加入0.1 mL乙酸酐进行衍生处理2 min后,经0.2 mL四氯化碳(萃取剂)与0.6mL异丙醇(分散剂)混合溶液分散萃取,在4 000 r/min下离心3 min,取下层有机相进行GC-MS分析。在优化实验条件下,5种含氯酚和邻苯基苯酚的线性范围为0.001~1 mg/L,相关系数为0.999 1~0.999 9,检出限(S/N=3)为0.5~5μg/kg,样品加标回收率为87.2%~103.7%,相对标准偏差为2.5%~4.8%。方法简单、灵敏,回收率和重复性良好,可用于纺织品中5种含氯酚和邻苯基苯酚的测定。     

柽柳实中挥发油和脂肪酸分析

首次研究了维药细穗柽柳(Tamarix leptostachys Bunge)实中挥发油和脂肪酸的化学成分。 分别采用药典中的挥发油提取法和索式取提法提取柽柳实中的挥发油和脂肪酸,使用气质联用技术获取总离子流图,各色谱峰相应的质谱图经过NIST2011标准谱库检索定性,并采用峰面积归一化法进行定量分析,计算各成分的相对百分含量。 两种方法分别鉴定出48种挥发油和19种脂肪酸。 挥发油主要成分为芳香类化合物(43.71%)、芳香性醛酮类(20.58%)、脂肪酸类(13.03%)、酯类(17.36%)和醇类(4.19%)等。 脂肪酸主要成分为棕榈酸(35.61%)、亚油酸(27.26%)和油酸(11.33%)等,其中不饱和脂肪酸含量占总脂肪酸含量的38.65%。 维药细穗柽柳实中富含丰富的挥发油和不饱和脂肪酸,具有很好的开发利用价值。     

海水小球藻中多糖的提取及其单糖组成的气相色谱-质谱分析

在温度为70℃、功率为600 W、提取时间为30 m in的条件下,海水小球藻中的多糖可以得到较好的提取。经过优化,当超声波作用时间为90 m in、超声波功率为300 W、水解液为1 mol/L乙酸时,小球藻多糖的超声水解效果最好。碱提、水提、酸提海水小球藻多糖中的单糖组成,经过GC-MS分析,它们的单糖组成各不相同。碱提粗多糖中所含单糖为鼠李糖、L-岩藻糖、D-阿拉伯糖、D( )-木糖、D-甘露糖、D-葡萄糖、D-半乳糖,各单糖百分含量分别为20.68%、0.32%、1.0%、2.20%、4.58%、50.28%、20.91%(W/W);水提海水小球藻粗多糖中含鼠李糖、核糖、岩藻糖、阿拉伯糖、木糖、甘露糖、葡萄糖、半乳糖8种单糖,它们百分比分别为2.32、2.36、0.24、0.89、0.56、3.44、78.21、11.99%(W/W);酸提粗多糖中所含单糖为鼠李糖、核糖、岩藻糖、阿拉伯糖、木糖、甘露糖、葡萄糖、半乳糖,各单糖百分含量分别为2.75、1.75、0.23、1.04、0.61、5.99、74.33、13.30%(W/W)。本实验所建立的微波辅助提取、超声水解多糖、GC-MS分析多糖中的单糖组成等方法,具有简便、快速、准确的特点。可用于海藻和其它植物中的多糖研究。     

"四物汤"中当归有效部位及有效成分的研究

研究发现“四物汤”中的当归对家兔主动脉血管有舒张作用的有效部位及有效成分。采用超临界CO2流体萃取当归中的脂溶性部位,经柱层析法分离和高效液相色谱法纯化,并结合细胞膜色谱法筛选和气相-质谱联用色谱法鉴定,确定当归中的有效成分。结果表明：当归脂溶性部位经柱层析分离得到的正己烷-醋酸乙酯洗脱部位为有效部位,其中藁本内酯、邻苯二甲酸二甲酯和邻苯二甲酸二乙酯等是当归中对兔主动脉血管有生理活性的有效成分。     

Rethinking the Process of Animal Mummification in Ancient Egypt: Molecular Characterization of Embalming Material and the Use of Brassicaceae Seed Oil in the Mummification of Gazelle Mummies from Kom Mereh,Egypt

The study of animal mummification in ancient Egypt has recently received increasing attention from a number of modern scholars given the fact that this part of ancient Egyptian funerary and religious history is a practice yet to be fully understood. In this study, nine samples of embalming matter were extracted from six gazelle mummies from the archaeological site of Kom Mereh (modern village of Komir), dated to the Roman period of dominance in ancient Egypt. All samples were analyzed for the presence of inorganic and organic matter applying a multi-analytical approach based on Fourier transform infrared spectroscopy (FT-IR) and gas chromatography–mass spectrometry (GC-MS). Furthermore, in order to identify more specific compounds such as bitumen and beeswax in studied balms, each sample was subjected to a solid phase extraction (SPE) and saponification separation process, respectively. The results of this study revealed that the majority of the analyzed embalming substances sampled from six gazelle mummies from Kom Mereh were complex mixtures of plant oils, animal fats, conifer resin, and beeswax. In this regard, this study was able to report a practice until now unmentioned in the scientific literature, namely, the use of cruciferous oil, derived from seeds of Brassicaceae plants, in animal mummification.     

Analysis of cypermethrin residues and its main degradation products in soil and formulation samples by gas chromatography-electron impact-mass spectrometry in the selective ion monitoring mode

A fast, simple and inexpensive sample preparation method based on the matrix solid-phase extraction (SPE) technique is proposed for the isolation of cypermethrin and its metabolite residues from soils. Both the extraction and clean-up procedures were carried out in two steps and target compounds were determined by gas chromatography coupled with electron-impact mass spectrometry (GC-EI/MS). The characteristic ions and fragmentation mechanism of cypermethrin were evaluated by electron impact ionization mass spectrometry (EI/MS). After the optimization of different parameters, such as the extraction solvent, the pesticide was extracted from the matrix with methanol/acetone in a Soxhlet extractor, cleaned up on a Florisil column by elution with a mixture of 30% ethyl acetate in n-hexane and analyzed by gas chromatography-electron impact ionization mass spectrometry (GC-EI/MS) in the selected ion-monitoring mode (SIM) with permethrin as internal standard. Recovery was in the range 77–118% with relative standard deviations (RSD) between 2.5% and 10.2%. The limit of detection (LOD) was 6.5?µg/kg for cypermethrin. The developed method was linear in the injection range 6–30?ng, with correlation coefficients greater than 0.9957.     

A membrane-protected micro-solid-phase extraction method based on molecular imprinting and its application to the determination of local anesthetics in cosmetics

As local anesthetics that are illegally added to cosmetics are harmful to consumer health, it is necessary to establish an efficient method for detecting these substances. Herein, a molecularly imprinted polymer (bupivacaine) was prepared by bulk polymerization and packed into a hollow fiber for use as an extraction phase to fabricate a membrane-protected micro-solid-phase extraction device. The optimal values of the influencing parameters for the microextraction process were as follows: a sample solution pH of 9.0, a loading and washing time of 2 h, and an elution time of 32 min. A gas chromatography-mass spectrometry method was established for the determination of local anesthetics and coupled with the microextraction method to successfully detect local anesthetics in cosmetic samples. The calibration curve for the proposed method was linear in the range of 0.4–50 mg/L and showed a good correlation coefficient (r²). The limits of detection for local anesthetics were in the range of 0.01–0.71 mg/L. The molecularly imprinted polymer exhibited good imprinting and selectivity, the micro-solid-phase extraction device was simple and inexpensive and fabrication was reproducible. The combination of molecular imprinting technology, membrane separation, and micro-solid-phase extraction methods used in this study can potentially be applied to pretreat local anesthetics in cosmetic samples.     

A QuEChERS‐based extraction method for the residual analysis of pyraclofos and tebufenpyrad in perilla leaves using gas chromatography: application to dissipation pattern

The objective of this work was to establish a simple extraction method for the residual analysis of pyraclofos and tebufenpyrad in Perilla leaves. A QuEChERS (quick, easy, cheap, effective, rugged and safe) method was used for extraction using ethyl acetate as an extraction solvent, and cleanup was carried out using dispersive solid‐phase extraction technique. The samples were analyzed using gas chromatography with nitrogen phosphorous detector and confirmed by gas chromatography–mass spectrometry. The linearity was excellent (r² = 1.0) in matrix‐matched calibration for both pesticides. The recoveries at two fortification levels were 80.76–95.38% with relative standard deviation lower than 5%. The limits of detection and limits of quantification were 0.01 and 0.033 mg/kg for both pesticides, respectively. The results revealed that the dissipation pattern of pyraclofos and tebufenpyrad followed first‐order kinetics. The pyraclofos and tebufenpyrad residues declined to a level below the maximum residue limits within 14 day between the last application and harvesting. We suggest that pyraclofos and tebufenpyrad could be used efficiently on perilla leaves under the recommended dosage conditions. Copyright © 2012 John Wiley & Sons, Ltd.     

Solid phase extraction for the speciation and preconcentration of inorganic selenium in water samples: A review

Selenium is an essential element for the normal cellular function of living organisms. However, selenium is toxic at concentrations of only three to five times higher than the essential concentration. The inorganic forms (mainly selenite and selenate) present in environmental water generally exhibit higher toxicity (up to 40 times) than organic forms. Therefore, the determination of low levels of different inorganic selenium species in water is an analytical challenge. Solid-phase extraction has been used as a separation and/or preconcentration technique prior to the determination of selenium species due to the need for accurate measurements for Se species in water at extremely low levels. The present paper provides a critical review of the published methods for inorganic selenium speciation in water samples using solid phase extraction as a preconcentration procedure. On the basis of more than 75 references, the different speciation strategies used for this task have been highlighted and classified. The solid-phase extraction sorbents and the performance and analytical characteristics of the developed methods for Se speciation are also discussed.     

Structure and Bonding Nature of the Strained Lewis Acid 3‐Methyl‐1‐boraadamantane: A Case Study Employing a New Data‐Analysis Procedure in Gas Electron Diffraction

Base‐free 3‐methyl‐1‐boraadamantane was synthesized by starting from its known THF adduct, transforming it to a butylate‐complex with n‐butyllithium, cleaving the cage with acetyl chloride to give 3‐n‐butyl‐5‐methyl‐7‐methylene‐3‐borabicyclo[3.3.1]nonane and closing the cage again by reacting the latter with dicyclohexylborane. The identity of 3‐methyl‐1‐boraadamantane was proven by ¹H, ¹¹B and ¹³C NMR spectroscopy and elemental analysis. The experimental equilibrium structure of the free 3‐methyl‐1‐boraadamantane molecules has been determined at 100 °C by using gas‐phase electron diffraction. For this structure determination, an improved method for data analysis has been introduced and tested: the structural refinement versus gas‐phase electron diffraction data (in terms of Cartesian coordinates) with a set of quantum‐chemically derived regularization constraints for the complete structure under optimization of a regularization constant, which maximizes the contribution of experimental data while retaining a stable refinement. The detailed analysis of parameter errors shows that the new approach allows obtaining more reliable results. The most important structural parameters are: r_e(B‐C)_av=1.556(5) Å, ${\angle }$ _e(C‐B‐C)_av=116.5(2)°. The configuration of the boron atom is pyramidal with ${\sum \angle }$ (C‐B‐C)=349.4(4)°. The nature of bonding was analyzed further by applying the natural bond orbital (NBO) and atoms in molecules (AIM) approaches. The experimentally observed shortening of the B? C bonds and elongation of the adjacent C? C bonds can be explained by the σ(C‐C)→p(B) hyperconjugation model. Both NBO and AIM analyses predict that the B? C bonds are significantly bent in the direction out of the cage.     

Analysis of microplastics and nanoplastics: How green are the methodologies used?

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