SFE of rosemary oil: Assessment of the influence of process variables and extract characterization

The effects of temperature and solvent density on the characteristics of the extracts obtained from supercritical fluid extraction (SFE) of the volatile compounds from Brazilian rosemary (Rosamarinus officianalis L., Labiatae) using carbon dioxide (CO₂) as solvent were investigated. The experiments were performed in a semi-batch laboratory scale home-made unit at two temperatures, viz. 310.15 and 320.15 K, over the pressure range of 100-160 bar. This study allowed to determine the crossover point and the maximum solubility of the oil. The products were analyzed by HRGC-MS, and compounds grouped in three different classes according to their molecular mass distribution in order to evaluate the influence of the variables studied on the characteristics of the extracts. The model proposed by Sovová was adopted in an attempt to interpret the mass transfer phenomena in the extraction process.     

佩兰挥发性化学成分的固相微萃取研究

采用固相微萃取-气相色谱-质谱法分析佩兰中挥发性化学成分,共分离出84个组分,并鉴定了67个组分,用归一化法测定其质量分数,占总挥发性组分峰面积的98.05%。主要成分是对-伞花烃(5.19%)、芳樟醇(3.72%)、β-石竹烯(12.35%)、α-律草烯(13.39%)、α-姜黄烯(2.11%)、(-)-石竹烯氧化物(8.25%)、. /-.-4-乙酰基-1-甲基环己烯(8.91%)。     

冷蒿挥发油化学成分的分离和鉴定

采用水蒸气蒸馏法提取了冷蒿挥发油,气相色谱-质谱联用结合计算机检索对其化学成分进行了分析和鉴定,共分离出106个峰,确定了101种化合物,它们主要是二甲基-甲撑基环庚(17.67%)、3,3,6-三甲基-1,5-庚二烯醇-2(16.40%)、3,3,6-三甲基-1,4-庚二烯醇-6(8.55%)、桉树脑(5.57%)、3,7-二甲-基2,6-辛二烯醇-1(3.85%)、神圣亚麻三烯(3.73%)、1-甲基-3-异丙基苯(3.26%)、桥环[2,2,1]萜烯(2.91%)、樟脑(2.26%)、香叶烯(2.20%),以上10种化合物占挥发油总量的66.40%。     

微波-同时蒸馏萃取分离肉桂挥发性成分分析

经粉碎的肉桂干燥树皮置于去离子水中微波加热处理后,用自制的同时蒸馏-萃取装置,以重蒸乙醚为溶剂将试样中的挥发组分萃取分离。用旋转蒸发器除去乙醚后即得到含有试样中挥发组分的透明的黄色液体,收得率为6.5%,应用GC/MS法对黄色液体的组分进行定性和定量分析。借助于联机的计算机和相关软件并用峰面积-归一化计算测得其中共有27个化合物,其中含量最高的是肉桂醛,达94.36%。另取部分上述挥发油(即黄色液体),用加成分解法将其中肉桂醛转化为一种加成产物以沉淀形式析出,即将黄色液体与NaHSO3共置于微波炉中,在不超过10℃的条件下处理直至加成物完全析出。将此加成物分出,并用0.1 mol.L-1盐酸进行水解处理,使加成物恢复成纯度较高的肉桂醛,用IR及MS对其组成及结构作进一步确认。     

共沸蒸馏GC/MS测定非卤代挥发性有机物的方法研究

讨论了用共沸蒸馏法浓缩处理水、土壤、固废样品或其萃取液中不易吹除、具挥发性、且易溶于水的非卤代挥发性有机物,并用气相色谱质谱联用仪定性定量的方法.     

Isolation and Determination of Volatile Organic Compounds from Water by Dynamic Purge-and-Trap Technique Coupled with Capillary Gas Chromatography

The preconcentration technique of purge-and-trap has been investigated in the present work for quantitative adsorption of volatile organic pollutants purged from water samples. A dynamic purging device with variable volume size has been constructed and tested to purge different concentrations of organic compounds. With Tenax GR as the adsorbent, a dynamic purge-and-trap technique was developed combining on-column preconcentration procedures using ambient trapping/thermal desorption/cryogenic focusing/back-flash injection prior to separation and determination using capillary gas chromatography. Various aromatic compounds in water were determined, giving linear working ranges over five orders of magnitude from 0.02 to 5000 µg/L. The analytical procedures were optimized under the assistance of ultrasonication with results validated for the determination of organic contaminants in underground water and tap water, giving over 93% recoveries and a detection limit of 0.01 µg/L, two orders of magnitude lower than those obtained using commercial available instruments with on-line configuration to minimize cross-contamination. The technique provides a potential automated method for in situ monitoring of volatile organic compounds in water.     

Chemotherapy control by breath profile with application of SPME‐GC/MS method

Chemotherapy used as a treatment against lung cancer has influence on metabolic processes occurring in healthy cells. The changes of biochemical pathways proceeded inside cells might be observed in expired air. In the experiment, breath analysis was carried out before and after anticancer therapy. Expired air samples were collected from 22 patients with a biopsy confirmed lung cancer. Volatile organic compounds present in breath were analyzed by gas chromatography/mass spectrometry. For enrichment of analytes solid‐phase microextraction technique was applied. Eight fibers covered by different sorbents were tested. Carboxen‐polydimethylsiloxane fiber revealed the highest extraction efficiency in relation to analytes in breath. The data showed that cytostatic drugs increase the concentration of acetone and isoprene in the breath collected after chemotherapy. Volatile metabolites of administrated drugs were not identified in expired air.     

Microextraction techniques for the determination of volatile and semivolatile organic compounds from plants: A review

Vegetables and fruits are necessary for human health, and traditional Chinese medicine that uses plant materials can cure diseases. Thus, understanding the composition of plant matrix has gained increased attention in recent years. Since plant matrix is very complex, the extraction, separation and quantitation of these chemicals are challenging.     

Comprehensive two‐dimensional gas chromatography coupled with static headspace sampling to analyze volatile compounds: Application to almonds

The hyphenation of static headspace sampling with comprehensive 2D GC equipped with a modulator based on capillary flow technology and a flame ionization detector was used to separate and identify 43 representative target volatile compounds (light hydrocarbons, carbonyls, pyrazines, alcohols, furans, and benzenes) frequently detected in the roasting process of nuts. Five column combinations with differing degrees of orthogonality (one conventional and four inverted phase sets) were tested in order to obtain the best conditions for analyzing these volatile compounds. Optimization of the working conditions for each of the different column combinations was performed by means of a central composite design. The best results in terms of separation and differentiation among the different chemical groups were achieved with a combination of inverted phase columns (first dimension: highly polar, INNOWax; second dimension: mid‐polar, ZB‐35). Additionally, a reference template was developed to provide an effective and rapid analysis of the target compounds. Finally, the proposed method was successfully employed to identify volatile compounds in raw and roasted almond samples from the Spanish cultivar Largueta.