吸附热脱附-气质联用技术分析烟丝中挥发及半挥发性成分

卷烟致香成分是卷烟质量的重要指标,利用吸附热脱附-气相色谱-质谱技术分析了烟丝中挥发及半挥发性成分79种,其中酸性物质17种,碱性物质5种,中性物质57种,为烟草化学研究提供了简单快速的分析方法.     

升温方式对真空冷冻干燥过程的影响

为了在保证冻干样品品质的同时缩短冻干时间,以猪主动脉为研究对象进行真空冷冻干燥.采用阶段升温方式与传统地一次干燥和二次干燥方式进行对比,结合脱水率、外观形态和力学性能,探讨阶段升温方式对缩短冻干时间的影响.实验结果表明,采用阶段升温方式明显缩短了干燥时间,且脱水率同样达到较高水平、外观形态和力学性能与采用传统方式所得样...     

分子蒸馏分离废次烟末致香成分及在烟草中的应用

采用分子蒸馏技术对超临界CO₂萃取的废次烟末提取物进行分离,并对馏分进行GC-MS分析。 GC-MS结果显示,三级分子蒸馏(80、120、160 ℃)共鉴定出52种化学组分。 80 ℃轻组分段鉴定出15种,以杂环类为主,占总量的98.91%;其次为酯类,占总量的0.606%。 120 ℃轻组分段鉴定出26种,以杂环类为主,占总量的91.42%;其次为酮类、醇类和烃类,分别占总量的4.16%、2.87%和0.74%。 160 ℃轻组分段鉴定出26种,以醇类为主,占总量的67.97%;其次为杂环类,占总量的11.57%,烃类、醚类、酮类、酯类、醛类分别占总量的7.9%、4.09%、3.77%、2.80%、1.89%。 不同馏分段化合物种类和含量存在明显差异性,充分体现了分子蒸馏选择性富集的特点。 感官评吸表明,80 ℃轻组分和120 ℃轻组分按照质量比8:2调配后,香气质较好,香气量较足,口腔较舒适,有甜香显现,吸味较纯净,评吸结果较为理想。     

谱图检索结合二级质谱定性分析烟草中挥发性成分

采用同时蒸馏萃取法提取烟叶中的挥发性成分,利用气相色谱-质谱联用仪(GC-MS)分离测定,通过谱库检索和匹配度定性结合色谱保留指数方法鉴定烟叶中挥发性成分,并引入离子阱二级质谱对谱库检索匹配度差距小、含量低,背景干扰大的物质准确定性.采用谱图检索结合二级质谱定性共鉴定144个化合物,其中104个化合物在烟草挥发性成分的文献中已有报道,报道中有9个化合物是通过二级质谱定性,其余40个化合物还未见报道.结果表明,离子阱二级质谱定性的引入提高了对未知化合物定性的准确性和可靠性,适合于烟叶这类复杂植物体系的化学组分研究.     

烘丝前后烟丝多元酸和高级脂肪酸变化研究

烟草中的多元酸对抽吸品质有重要影响,它们能与生物碱结合成盐,调节烟草中碱性成分的挥发性。高级脂肪酸可分成饱和与不饱和两类,饱和脂肪酸能增加烟气的脂肪味、腊味并使之圆和;不饱和脂肪酸增加烟气的丰满度和粗糙感。卷烟在烘丝过程中由于温度、湿度的变化而引起烟草内部化学成分的变化。本文应用甲酯衍生化和GC-MS法,对卷烟加工过程中烘丝工序前后的多元酸和高级脂肪酸进行了定性定量分析。为卷烟配方和加工工艺参数的优化提供理论依据。     

烟梗中的中性致香成分定性定量分析

采用带MS Vent装置的气质联用仪,同时实现MS定性和FID定量,对烤烟烟梗中性致香成分进行定性定量分析,共分离鉴定出40种成分.方法回收率介于85.69%～100.39%之间,精密度达到0.28%.结果表明,该方法简便、快捷、可靠,为全面评价烟草质量提供一种有效的分析手段.     

液相色谱/质谱法测定电气产品塑料部件中的初级芳香胺

采用高效液相色谱/质谱(HPLC-MS)法,对电子电气产品塑料部件中的26种初级芳香胺进行了同时测定.初级芳香胺用二氯甲烷、丙酮、甲醇等有机溶剂提取,然后浓缩提取液,用甲醇定容,最后用高效液相色谱/质谱联用仪分析检测.采用ZORBAX Eclipse XDB-C18色谱柱,流动相为乙腈-0.1%甲酸溶液,流速为0.6 mL/min,选择离子监测.26种禁用芳香胺的线性范围为0.1～10.0 mg/kg; r≥0.997; 检出限为0.05 mg/kg; 加标回收率为70%～110%; 相对标准偏差为0.23%～14.9%.结果表明, HPLC-MS法可以对塑料部件中的初级芳香胺进行定性定量测定.本研究选择离子色谱峰分离效果好,具有良好的稳定性和重现性.     

熔融制样-X射线荧光光谱法测定镜铁矿中主次成分

以Li₂B₄O₇和LiBO₄[m（Li₂B₄O₇）：m（LiBO₄）=67：33]为熔剂,采用1：25熔剂稀释比,于1 120℃将镜铁矿试样熔融制成玻璃熔片,X射线荧光光谱分析仪对熔片中Fe、Mn、Ti、Ca、Ba、Al、Mg、K、Na和P等元素进行同时测定.由于样品采用大的熔剂稀释比进行高温熔融,有效提高了K、Na等元素的X射线荧光强度,消除了复杂矿物结构效应,降低共存元素间基体效应影响,提高了分析结果的准确度和精密度.方法用于铁矿石标样分析,各组分的测定值与标准值相符.     

Impact of Drying Methods on Phenolic Components and Antioxidant Activity of Sea Buckthorn (Hippophae rhamnoides L.) Berries from Different Varieties in China

Sea buckthorn berries are rich in bioactive compounds and can be used for medicine and food. The variety and drying method used have an important influence on quality. In this study, different sea buckthorn varieties from China were selected and dried with four common drying methods. The total phenolic content (TPC), total flavonoids content (TFC), contents of 12 phenolic compounds and antioxidant capacity in vitro were analyzed. The results showed that the TPC, TFC and antioxidant activity of two wild sea buckthorn berries were higher than those of three cultivated berries, and for the same varieties, measured chemical contents and antioxidant activity of the freeze-dried fruit were significantly higher than those obtained with three conventional drying methods. In addition, forty-one compounds in sea buckthorn berry were identified by UPLC-PDA-Q/TOF-MS, most of which were isorhamnetin derivatives. Multivariate statistical analysis revealed narcissin and isorhamnetin-3-O-glucoside varied significantly in sea buckthorn berries of different varieties and with different drying methods; they were potential quality markers. Strong correlations were found between TPC, gallic acid and antioxidant capacity (p < 0.05). The results revealed how components and antioxidant activity varied in different sea buckthorn, which provides a valuable reference for quality control and further development and utilization of sea buckthorn.     

Experimental Investigation on the Mass Diffusion Behaviors of Calcium Oxide and Carbon in the Solid-State Synthesis of Calcium Carbide by Microwave Heating

Microwave (MW) heating was proven to efficiently solid-synthesize calcium carbide at 1750 °C, which was about 400 °C lower than electric heating. This study focused on the investigation of the diffusion behaviors of graphite and calcium oxide during the solid-state synthesis of calcium carbide by microwave heating and compared them with these heated by the conventional method. The phase compositions and morphologies of CaO and C pellets before and after heating were carefully characterized by inductively coupled plasma spectrograph (ICP), thermo gravimetric (TG) analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The experimental results showed that in both thermal fields, Ca and C inter-diffused at a lower temperature, but at a higher temperature, the formed calcium carbide crystals would have a negative effect on Ca diffusion to carbon. The significant enhancement of MW heating on carbon diffusion, thus on the more efficient synthesis of calcium carbide, manifested that MW heating would be a promising way for calcium carbide production, and that a sufficient enough carbon material, instead of CaO, was beneficial for calcium carbide formation in MW reactors.