Comparison of hydrodistillation and ultrasonic solvent extraction for the isolation of volatile compounds from two unifloral honeys of Robinia pseudoacacia L. and Castanea sativa L

A comparative study of ultrasound-assisted extraction (USE) with the mixture pentane:ether (1:2) and hydrodistillation (HD) with the same trapping mixture is presented for the isolation of volatile compounds from two unifloral honeys of Robinia pseudoacacia L. and Castanea sativa L. All HD isolates contained many thermally derived artefacts (especially phenylacetaldehyde with lower percentages of furfural, cis- and trans-linalool oxides and others). USE method gave the most representative profile of all honey volatiles (without artefacts). In addition, USE enabled extraction of low molecular weight semivolatile markers (especially benzoic, vanillic and phenylacetic acids) that were not extracted by HD. In this regard, low percentage of benzoic acid (0.7–7.4%), vanillic acid (0.0–1.6%) and phenylacetic acid (0.5–4.1%) was determined in Rp USE extracts, while Cs USE extracts contained phenylacetic acid (20.2–23.5%) as the major constituent with low percentage of benzoic acid (2.5–5.5%).     

Analysis of pesticide multi-residues in leafy vegetables by ultrasonic solvent extraction and liquid chromatography-tandem mass spectrometry

Ultrasonic solvent extraction (USE) of pesticide multi-residues including monocrotophos, dimethoate, imidacloprid, carbendazim, carbaryl and simazine from leafy vegetables is presented. The extraction procedure was optimized with regard to the solvent type and amount, sonication time and number of extraction steps. The extract did not need clean-up before injected into liquid chromatography-tandem mass spectrometry (LC-MS-MS) which was employed together with electron microscope to verify the effect of USE method. The proposed procedure allows the extraction of six pesticide residues in a single step with 40 ml of ethyl acetate for 35 min sonication, providing recovery over 83% and LOQ less than 1.4 microg/kg. The optimized USE method is a simple, low cost and an effective preparation method for determination of pesticide multi-residues at trace levels in leafy vegetables in comparison with homogenized extraction method.     

Shock wave-assisted extraction of phenolic acids and flavonoids from Eysenhardtia polystachya heartwood: A novel method and its comparison with conventional methodologies

Phenolic compounds, obtained from plants are important in the food, biomaterial and pharmaceutical industries; however current extraction methods, such as Soxhlet (solid-liquid) extraction, liquid-liquid extraction, microwave-assisted extraction, and ultrasonic extraction (USE), have the disadvantages of large processing times, contamination by solvents, and degradation of analytes. This study demonstrates that shock wave-assisted extraction can be used as a more efficient, eco-friendly and rapid method. Extraction of powdered samples of Eysenhardtia polystachia heartwood, a plant with high concentration of phenolic compounds, exposed to different doses of underwater shock waves, was compared with the conventional methods. Our results revealed that shock wave-assisted extraction (1500 shock waves with a peak positive pressure of approximately 88 MPa) produced 34.54% and 31.95% higher contents than Soxhlet and USE, respectively. Extraction times using shock waves were much shorter than with all other methods tested, proving that it is an attractive method to obtain both phenolic acids and flavonoids without the need for organic solvents. Furthermore, shock waves produced a significantly higher content of total reducing sugars than Soxhlet extraction and less phenolic acids which gives the insight of a more selective extraction of components.     

顶空固相微萃取-气相色谱-质谱联用分析马蹄香中的挥发油成分

利用顶空固相微萃取-气相色谱-质谱联用技术分析马蹄香挥发油的化学成分,为马蹄香的挥发油成分分析提供新方法。以顶空固相微萃取法提取挥发油,气相色谱-质谱联用技术对挥发油成分进行分离鉴定,并采用面积归一化法确定各成分的相对质量分数。结果样品在90℃下平衡30min,顶空吸附15min的条件下,采用100μm PDMS纤维头能有效地吸附马蹄香挥发油成分。气相色谱-质谱联用技术共鉴定出57个成分,其中相对质量分数较高的有西车烯(15.93%)、1,2,3,5,6,7,8,8a-八氢-1,4-二甲基-7-(1-甲基乙烯基)甘菊蓝(13.55%)、α-广藿香烯(9.50%)等。马蹄香挥发油具有丰富的化学成分,顶空固相微萃取-气相色谱-质谱联用能全面快速地获得其组成信息,可应用于马蹄香挥发油成分的研究。     

Components of supercritical extracts of garlic and synthetic nonsymmetrical allyl disulfides as potential antimicrobial preparations

Extracts of garlic (Allium sativum L.) were obtained using supercritical carbon dioxide extraction and were separated into individual compounds using preparative high performance liquid and gas chromatography. A series of nonsymmetrical allyl disulfides with different substituents were synthesized. The compounds isolated from the supercritical garlic extract and the synthetic nonsymmetrical allyl disulfides (SNA) were tested as potential antimicrobial agents using a number of test objects: Candida utilis, Bacillus cereus, Pseudomonas aurantiaca, and Escherichia coli. It was shown that the SNA exhibit high antimicrobial activity, which was much higher that the activities of individual components of garlic and in some cases were comparable in efficiency with antibiotics of the floxacin series widely used in clinical practice. The data obtained suggest the potential for using SNA as antimicrobial agents.     

东北苍耳子挥发油化学成分分析

利用乙醚抽提东北苍耳子挥发油,GC-MS结合计算机检索对其化学成分进行分析鉴定,用色谱峰面积归一化法计算各组分的相对含量.分离出89个组分,鉴定了其中74个组分,占总挥发油量的85.63%.东北苍耳子挥发油的主要成分为3-甲基丁酸(16.421%)、3-甲基-戊酸(15.882%)、苯乙醛(11.281%)、已酸(5.051%)、糠醛(4.716%)、苯甲醇(2.358%)、苯乙醇(2.282%)等.     

气相色谱-质谱法研究香稻品种白香糯化学成分

本文采用同时蒸馏－萃取法（Ｓｉｍｕｌｔａｎｅｏｕｓ Ｄｉｔｉｌｌａｔｉｏｎｓ－Ｅｘｔｒａｃｔｉｏｎ,ＳＤＥ）提取了香稻品种－白香糯的挥发性香味成分,采用气相色谱－质谱（ＧＣ／ＭＳ）联用技术鉴定了白香糯的２３种非酸性香气成分。对其中最重要的香气成分２－乙酰基－２－吡咯啉进行了定量测定。     

New insights into the mechanisms of ultrasonic emulsification in the oil–water system and the role of gas bubbles

Ultrasonic emulsification (USE) assisted by cavitation is an effective method to produce emulsion droplets. However, the role of gas bubbles in the USE process still remains unclear. Hence, in the present paper, high-speed camera observations of bubble evolution and emulsion droplets formation in oil and water were used to capture in real-time the emulsification process, while experiments with different gas concentrations were carried out to investigate the effect of gas bubbles on droplet size. The results show that at the interface of oil and water, gas bubbles with a radius larger than the resonance radius collapse and sink into the water phase, inducing (oil–water) blended liquid jets across bubbles to generate oil-in-water-in-oil (O/W/O) and water-in-oil (W/O) droplets in the oil phase and oil-in-water (O/W) droplets in the water phase, respectively. Gas bubbles with a radius smaller than the resonance radius at the interface always move towards the oil phase, accompanied with the generation of water droplets in the oil phase. In the oil phase, gas bubbles, which can attract bubbles nearby the interface, migrate to the interface of oil and water due to acoustic streaming, and generate numerous droplets. As for the gas bubbles in the water phase, those can break neighboring droplets into numerous finer ones during bubble oscillation. With the increase in gas content, more bubbles undergo chaotic oscillation, leading to smaller and more stable emulsion droplets, which explains the beneficial role of gas bubbles in USE. Violently oscillating microbubbles are, therefore, found to be the governing cavitation regime for emulsification process. These results provide new insights to the mechanisms of gas bubbles in oil–water emulsions, which may be useful towards the optimization of USE process in industry.     

Ultrasonic-assisted extraction,fatty acids identification of the seeds oil and isolation of chemical constituent from oil residue of Belamcanda chinensis

Belamcanda chinensis is a common garden herb. The extraction technology of B. chinensis seed oil (BSO) was optimized by ultrasonic-assisted extraction (UAE) method, the composition, relative content of main fatty acids and physicochemical properties of BSO were determined, and the isolation, identification and determination of chemical constituent in BSO residue (BSOR) were also investigated. The optimum process conditions of BSO by UAE were optimized as ultrasound time 14 min, extraction temperature 42℃, the ultrasound power 413 W and the liquid–solid ratio 27:1 mL/g. Under this condition, the extraction yield was 22.32 % with the high contents of linoleic acid and oleic acid in BSO. Ten compounds were isolated and identified from BSOR, and belamcandaoid P (9) was a new compound. The contents of the determined compounds were all at high level in B. chinensis seed. The study provided a certain scientific reference for the comprehensive development and utilization of B. chinensis seeds.     

Bio-refinery of orange peels waste: A new concept based on integrated green and solvent free extraction processes using ultrasound and microwave techniques to obtain essential oil,polyphenols and pectin

In this study, extraction of essential oil, polyphenols and pectin from orange peel has been optimized using microwave and ultrasound technology without adding any solvent but only “in situ” water which was recycled and used as solvent. The essential oil extraction performed by Microwave Hydrodiffusion and Gravity (MHG) was optimized and compared to steam distillation extraction (SD). No significant changes in yield were noticed: 4.22 ± 0.03% and 4.16 ± 0.05% for MHG and SD, respectively. After extraction of essential oil, residual water of plant obtained after MHG extraction was used as solvent for polyphenols and pectin extraction from MHG residues. Polyphenols extraction was performed by ultrasound-assisted extraction (UAE) and conventional extraction (CE). Response surface methodology (RSM) using central composite designs (CCD) approach was launched to investigate the influence of process variables on the ultrasound-assisted extraction (UAE). The statistical analysis revealed that the optimized conditions of ultrasound power and temperature were 0.956 W/cm² and 59.83 °C giving a polyphenol yield of 50.02 mg GA/100 g dm. Compared with the conventional extraction (CE), the UAE gave an increase of 30% in TPC yield. Pectin was extracted by conventional and microwave assisted extraction. This technique gives a maximal yield of 24.2% for microwave power of 500 W in only 3 min whereas conventional extraction gives 18.32% in 120 min. Combination of microwave, ultrasound and the recycled “in situ” water of citrus peels allow us to obtain high added values compounds in shorter time and managed to make a closed loop using only natural resources provided by the plant which makes the whole process intensified in term of time and energy saving, cleanliness and reduced waste water.     

Insights into ultrasound-promoted degradation of naphthenic acid compounds in oil sands process affected water. Part I: Accelerated H-abstraction and decarboxylation of aromatic and alicyclic compounds

Propelled by enormous increase in demand for fuel sources, Canadian oil sands are becoming increasingly important as a fuel source due to their abundance and upgrading capability. However, extraction of bitumen, a high acid crude (HAC) oil, requires 2–3 units of water per unit of oil resulting in naphthenic acid (NA)-rich oil sands process affected water (OSPW) collected in effluent ponds. This study illustrates the role of sonochemistry in the accelerated degradation through H-abstraction and subsequent decarboxylation of aromatic and alicyclic naphthenic acid model compounds. Benzoic acid and 3-methylcyclohexane carboxylic acid were selected as model NA compounds to investigate the mechanism of hydroxyl radical (OH^•) initiated carboxylic acid degradation in 378 KHz sonochemical reactor. Established FTIR methods with low resolution LCMS spectroscopy confirmation were applied to determine the extent of carboxylic acid degradation and identify the formation of products. FTIR monitoring showed a non-linear degradation of carboxylic acids with formation of many intermediates highlighting the shift from cyclic carboxylic acids to cyclic alcohols during BA degradation. Subsequent decrease in carboxylic acid groups signifies scission of cyclic structures before complete mineralization. This is confirmed with the LCMS identification of products such as: 3-hydroxybenzoic acid and phenol. This study postulated new breakdown pathways for degradation of benzoic acid with complete mineralization at a sonochemical reaction time (SRT) of 4 h. A radical quenching process was also inferred through the formation of conglomerates during sonochemical degradation of BA. Extension of the study to 3-methylcyclohexane carboxylic acid (3mCHA) shows similar non-linearity with an increase in carboxylic acid groups indicating H-abstraction followed by ring-opened compounds. However, due to the complex nature of 3mCHA’s ring-opened compounds, complete mineralization is not achieved. The putative role of sonochemistry is a promising and sustainable degradation method for mitigating NAs in OSPW, but sonication periods need to be considered carefully to ensure adequate mineralization of their constituents and combinatorial methods with other advanced oxidation methods may be needed to enhance industrial application.In Part II, an in silico screening approach using first principles is reported to identify the breakdown of the organic compounds and determine molecular rates of reaction to confirm the mechanistic origins of the compounds formed.     

以香草素为内标之气相层析光谱法定量牛樟木精油指标成分松油醇的快速分析方法

牛樟精油具有独特浓郁的香气,其中以α-松油醇(α-terpineol)为牛樟精油主要成分。由于樟树精油制品可依种类、变种、亚种等不同而有不同成分,以松油醇最具独特性,可作为牛樟木精油品质重要指标成分,应用以区别牛樟树与冇樟以及香樟等木材精油的方法,因此建立市售牛樟木精油指标成分α-松油醇含量的简便快速又准确的检验方法便有其必要性。该研究拟以市售精油液体样品,不经任何前处理,加入适当之内标准溶液溶解后,直接注入气相层析光谱仪中,配合适当的分离管柱及气相层析条件,以期建立简便快速又准确的牛樟木精油指标成分α-松油醇之定量方法。毛细管柱气相层析具有高解析度及高灵敏度等优点,仍为现代最重要分析技术之一,因此研究建立了以香草素为内标准定量牛樟木精油指标成分α-松油醇(α-terpineol)之气相色谱层析法的快速分析方法。牛樟木精油液体样品,加入适当量之香草素内标准溶液混合溶解后,即可直接注入配有广口径之毛细管柱(megabore column)气相色谱仪中分析,相当简便,每分析一个样品仅需约30 min。结果显示松油醇之最低定量浓度（limit of quantitation, LOQ）为1 μg·mL-1左右。在添加回收试验中添加松油醇1.0及10.0 mg 于市售冇樟精油及牛樟精油中,其回收率在98%~103%,变异系数均在10.8%以下,显示该方法的精密度相当高。以该研究建立的方法分析15件市售牛樟精油中松油醇含量,结果显示,市售牛樟木精油的松油醇含量最高约51.6%及最低为21.3%左右,此结果显示以定量松油醇作为市售牛樟精油品质指标是一快速、准确且可行的方法。     

Molecular diversity of volatile compounds in rare willow (<Emphasis Type="BoldItalic">Salix</Emphasis> spp.) honeydew honey: identification of chemical biomarkers

Salix spp. honeydew honey volatiles were analyzed for the first time by headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE) followed by gas chromatography and mass spectrometry (GC, GC-MS). The use of HS-SPME and USE had advantageous results over the use of one single technique, as it provided different complementary chromatographic profiles for a comprehensive screening of the honeydew volatile composition. The volatiles with different functionality, molecular weight, and polarity were extracted and identified. High percentages of benzoic acid, phenylacetic acid, 2-hydroxybenzoic acid, 4-hydroxyphenylacetic acid with minor percentages of 4-methoxybenzoic acid, 4-hydroxyphenylethanol, and 4-hydroxybenzoic acid from USE extracts can be emphasized as volatile biomarkers of this honeydew that probably originated from Salix spp., as well as methyl salicylate identified only by HS-SPME. The application of heat treatment at 80 °C for 2 h did not change significantly the volatile composition of this honeydew.     

基于高效分离不皂化物的傅里叶红外光谱结合化学计量学鉴定芝麻油

芝麻油是日常生活中常用食用油之一,掺假芝麻油会导致严重的健康问题.研究芝麻油鉴定方法是非常重要的.皂化植物油提取不皂化物是食用油鉴定的经济方法之一,现有植物油皂化方法需要较长时间,较高的温度,且不皂化物提取过程非常繁琐.采用超声技术替代常规回流加热法,提高了皂化效率,皂化时间缩短至10分钟,在此基础上采用专用固相萃取(...     

Quantitative determination of oil content in small quantity of oilseed rape by ultrasound-assisted extraction combined with gas chromatography

Accurately quantitative determination of oil content in oilseed rape plays an important role in varieties breeding for improving oil content in seeds. However, large quantity of oilseeds were needed in order to obtain accuracy and precision results by using standard Soxhlet extraction method, which may be a handicap in analysis of small, rare and precious samples in plant breeding. In the present work, ultrasound-assisted extraction was evaluated as a simpler and more effective alternative to conventional extraction method for the isolation of oil from small quantity of oilseed rape (<20 mg). The oil of oilseed rape samples was extracted by ultrasound-assisted method, and then the fatty acids and total oil content of the seeds were qualitatively and quantitatively determined by gas chromatography (GC). Extraction efficiency of total oil obtained by ultrasound-assisted extraction through an orthogonal experiment (L(9) (3(4))) were investigated to get the best extraction conditions. Statistical analysis showed that the variable with the largest effect was the ultrasound-assisted extraction time which was followed by the ultrasound-assisted extraction power, and the liquid:solid ratio. A liquid:solid ratio of 1:4 (L:g), an ultrasound-assisted extraction time of 60 min and an ultrasound-assisted extraction power of 500 W were found to be optimal for oil extraction from oilseed rape. By comparing with the conventional method, it was found that the ultrasound-assisted extraction of oil from oilseed rape was about five times faster than the traditional extraction method. By the use of ultrasound-assisted extraction combined with GC analysis, the fatty acids and total oil content in small quantity of seeds (<20 mg) were successfully qualitatively determined and the results are in agreement with that obtained by traditional standard method.     

蛇百子中挥发油成分的GC-MS分析

对蛇百子全草中挥发油部分进行分析,研究其化学成分。采用水蒸气蒸馏法提取获得总挥发油（Ⅰ）,乙醚萃取得到挥发油（Ⅱ）,再用乙酸乙酯进一步提取得到挥发油（Ⅲ）,通过GC-MS技术对其进行分析。共分离鉴定出化学成分48种,其中挥发油（Ⅰ）鉴定出36种化合物、挥发油（Ⅱ）鉴定出30种化合物、挥发油（Ⅲ）鉴定出10种化合物。挥发油的主要成分为反式石竹烯、1,8-桉树脑、侧柏烯、α-香柑油烯、β-榄香烯、桉树脑、γ-古芸烯等。     

微波消解-ICP-OES,AAS和AFS测定大蒜不同部位20种元素含量

将大蒜植株分为根、茎(下)、茎(中)、茎(上)、嫩叶和老叶6个不同部位,采用微波消解方法对各个部位进行了预处理,并用电感耦合等离子体发射光谱法(ICP-OES)、原子吸收光谱法(AAS)和原子荧光光谱法(AFS)测定了其中Al,As,B,Ca,Cd,Cr,Cu,Fe,Hg,K,Mg,Mn,Na,Ni,P,Pb,S,Se,Sr和Zn共20种元素的含量,另外,还测定了从同一处土壤中采收的大蒜头中相应元素的含量.研究结果表明:大蒜植株嫩叶和大蒜头中Cu,Fe,Mn,S,Se,Zn等元素含量较高而As,Cd,Hg,Pb等元素含量较低,是提取大蒜生物活性物质的绝好材料;一些元素在大蒜植株不同部位的含量分布模式能高度反映植物生理特性或环境污染状况.     

Mass spectrometric study of the repolymerization of (SN)x

A mechanism for the repolymerization of (SN)_x, is proposed on the basis of mass spectral studies (ion abundances and appearance potentials) on its vapor, and the previously postulated mechanism of polymerization of S₂N₂ from S₄N₄. Thermal decomposition of the polymer leads to acyclic (SN)_x, x ⩾ 2, which is the essential element for repolymerization, and also to cyclic combination products of SN radicals.Obviously, if only acyclic components are present, they need only combine. Cyclic products present in the condensate will slowly decompose to SN. The decomposition will be accelerated by the presence of polymeric chains, since SN will react with the polymer and integrate therein.     

Thermal destruction of asphaltites in supercritical fluids

The processes of thermal destruction of asphaltites recovered from the Rafaelita and Toribia deposits in the presence of water, benzene, tetralin, and ethanol in the supercritical state are studied. The solvent nature plays an important role in the thermal destruction, with the maximum conversion (99 wt %) of both asphaltites into liquid products being achieved in a tetralin medium. Not more than 70 wt % of asphaltites is converted into synthetic oil in an aqueous medium. High-molecular compounds, resins, and asphaltenes, the total content of which amounts to more than 60 wt %, are the main components of the liquid products. No more than 40 wt % asphaltene structures, 33 wt % resins, and 40 wt % oils are formed in tetralin and ethanol media. In all the experiments, saturated hydrocarbons and polyaromatic structures are the main components of oil. A high content of saturated and polyaromatic hydrocarbons found in the products of asphaltite cracking is probably due to the destructive hydrogenation and dissolution of asphaltite organic matter.     

Molecular Compton profiles from SCF-MO wavefunctions

Compton profiles are derived from ab initio SCF-MO wavefunctions calculated for cyclopropane, propene, aziridine, ethanimine, ethenamine, oxirane, acetaldehyde and formamide using Dunning's gaussian orbital basis. Good agreement with the experimental profile is found for formamide. The differences between the profiles for the cyclic and acyclic isomers are only slightly larger than the experimental accuracy that can presently be achieved. The cyclic compounds have slightly broader profiles and there are no significant differences arising from strain. Comparison with profiles derived from localized orbital contributions indicate that the localized orbital approach is essentially valid for these systems.