Application of Hyphenated Chromatography–Mass Spectrometry Techniques to Plant Allelopathy Research

Plant allelopathy offers hope as an additional means of weed control in modern agriculture. Its mechanisms and molecular basis are not yet well understood. Research on the chemical basis for allelopathy has often been hindered by the complexity of plant and soil matrices, making it difficult to track active compounds. Recent improvements in the cost and capabilities of bench-top chromatography–mass spectrometry instruments make these tools more powerful and more widely available to assist with molecular studies conducted in today's expanding field. Such instrumental techniques are herein recommended as economically efficient means of advancing the rigor of allelopathy research and assisting the development of a better understanding of the chemical basis for the allelopathy phenomenon.     

Migrated phthalate levels into edible oils

The determination of phthalates in edible oils (virgin olive oil, olive oil, canola oil, hazelnut oil, sunflower oil, corn oil) sold in Turkish markets was carried out using gas chromatography–mass spectrometry. Mean phthalate concentrations were between 0.102 and 3.863 mg L^?1 in virgin olive oil; 0.172 and 6.486 mg L^?1 in olive oil; 0.501 and 3.651 mg L^?1 in hazelnut oil; 0.457 and 3.415 mg L^?1 in canola oil; 2.227 and 6.673 mg L^?1 in sunflower oil; and 1.585 and 6.248 mg L^?1 in corn oil. Furthermore, the influence of the types of oil and container to the phthalate migration was investigated. The highest phthalate levels were measured in sunflower oil. The lowest phthalate levels were determined in virgin olive oil and hazelnut oil. The highest phthalate levels were determined in oil samples contained in polyethylene terephthalate.     

Effect of cooking or handling conditions on the furan levels of processed foods

The aim of this study was to investigate the possible effects of cooking or handling conditions on the concentration of furan in processed foods. The analytical method used to analyse furan levels in foods was optimized based on solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). In baby soups, the concentration of furan decreased by up to 22% after opening a lid for 10 min. In the baby food in retort packaging, the level of furan was reduced by 15–33% after heating the foods at 50°C without a lid. Furan in rice seasonings was evaporated completely after heating the foods at 60°C. Regarding powered milk, the levels of furan were too low to be compared under various conditions. The levels of furan decreased to 58% in beverage products for babies, after storing them at 4°C for 1 day without a lid. The levels of furan in canned foods such as cereal and vegetable were reduced by zero to 52% when they were stored without stirring in a refrigerator at 4°C for 1 day. When we boiled canned fish, the furan present was almost completely evaporated. It is recommended that canned meats be heated up to 50–70°C for the reduction (26–46%) of furan levels. The levels of furan in instant and brewed coffee samples were significantly reduced after storing for 11 to 20 min at room temperature without a lid (p < 0.05).     

The influence of polymer morphology on the performance of molecularly imprinted polymers

This is the first in-depth study examining the effect of morphology on the performance of 2-aminopyridine (2-apy) imprinted polymers. A series of polymers were prepared by varying the amount of crosslinking monomer (EGDMA) whilst the other polymer components remained constant. Physical characterisation was carried out using conventional techniques, such as nitrogen sorption porosimetry and solvent swelling studies. The use of a novel thermal desorption GC-MS technique suggested higher levels of polymer degradation with prolonged exposure to elevated temperatures for those polymers formed with lower amounts of EGDMA. The thermal desorption GC-MS profiles obtained correlated with the physical characteristics of the polymers, where higher levels of polymer bleed was found to occur with larger average pore diameters. Polymer physical characteristics were also found to correlate with the binding parameters (number of binding sites and polymer-template association energy) obtained from the Langmuir-Freundlich Isotherm (L-FI) and affinity distribution spectra (AD). The flexibility of the polymers formed from lower amounts of EGDMA combined the swelling effect of the solvents on the polymers resulted in an increase in affinity, which was both specific and non-specific in nature.     

煤焦油色质模拟蒸馏的研究

本文研究了色质模拟蒸馏的方法 ,考察了诸如色谱柱子类型、固定液的性质和厚度、柱长等影响模拟蒸馏分析的设备因素 ,探讨了诸如升温速率、炉温、载气流速、基线设置等操作条件对模拟蒸馏结果的影响 ,确定了最佳操作条件 ,并获得煤焦油的色质模拟蒸馏曲线     

一种未知涂料的化学成分剖析

采用红外光谱、气质联用仪对一种未知涂料的化学成分进行分析,对涂料的红外光谱进行解析、联机检索并定性,用气质联用数据进行验证、补充,确定出该涂料的主要成分。     

金莲花挥发油成分分析及其在单料烟加香中的应用

分别采用水蒸气蒸馏、同时蒸馏萃取、超声、闪式、先超声后同时蒸馏萃取,先闪式后同时蒸馏萃取6种提取方法提取金莲花挥发油,运用GC-MS分析挥发油的成分,并进行单料烟加香试验。结果表明：①金莲花挥发油得率分别为0.20%、0.67%、2.31%、2.67%、0.82%、0.78%,分别鉴定出20、30、19、18、37、30种成分;其中β紫罗兰酮、二氢猕猴桃内酯等为主要的香气成分;超声和闪式提取方法虽然挥发油得率高,但是杂质也较多,先超声后同时蒸馏萃取的挥发油优于其他几种。②在烟丝中,添加适量金莲花挥发油,能提高卷烟烟气的香气质和香气量,降低刺激性,改善余味,先超声后同时蒸馏萃取的挥发油加香效果最好。