烟草制丝过程中生物碱的变化研究

采用毛细管气相色谱分离、氢火焰离子化检测,分析了卷烟制丝过程中松片回潮、润叶加料、烘丝三个关键生产工序前后的总生物碱和游离生物碱的含量变化。研究结果表明,高温烘丝工序对总生物碱和游离生物碱的降低最为显著,润叶加料工序次之,松片回潮工序变化幅度最小。这三个关键卷烟制丝加工工艺过程中总生物碱的降低幅度达15%,游离生物碱降低达25%。试验研究结果对卷烟制丝工序质量评价、合理控制产品内在质量及其稳定性,具有一定理论指导意义和实际应用价值。     

高效液相色谱法测定CO2膨胀前后烟丝中氨基酸

本文研究了用Waters柱前衍生试剂AQC,即6-氨基喹啉基-N-羟基琥珀酰亚氨基酸甲酸来测定CO2膨胀前后烟丝中的氨基酸的组成和含量,流动相由磷酸盐缓冲液、乙腈和纯水构成,梯度洗脱。结果表明:烟丝在CO2膨胀前后样品所测16种游离氨基酸的总量普遍减少。     

制丝工艺改进中过程能力分析的运用探讨

各烟草企业为提高生产水平,创造更多的经济效益,纷纷对固有的制丝工艺加以改进,并采用过程能力分析法把握制丝过程中各环节的质量。本文提出了烟卷制丝工艺中的不足,并结合实例对过程能力分析在制丝工艺中的应用进行了分析。     

制丝加料前后非挥发性有机酸和高级脂肪酸变化分析

应用中甲酯衍生化和气相色谱法,分析烟叶样品的非挥发性有机酸和高级脂肪酸的含量,重复性较好.且分析时间较短。共鉴定制丝加料前后的6种非挥发性有机酸和4种高级脂肪酸的含量,结果表明:加料后,非挥发性有机酸和高级脂肪酸的含量均有不同程度的上升。     

藏药牦牛血粉饮片中氨基酸和无机元素测定

为建立藏药牦牛血粉饮片中氨基酸和无机元素的定性和定量分析方法,试验采用高效液相色谱-柱后衍生法对牦牛血粉中游离氨基酸进行测定:离子交换柱(2.5 mm×150 mm,6μm),检测波长为570 nm、440 nm,测试方法为单点矫正法;采用微波消解-ICP-MS对牦牛血粉中无机元素进行测定:测定模式为碰撞反应模式,碰撞气(He)流量5 mL/min。数据采集模式:跳峰扫描,采样深度8.0 mm,重复扫描3次。结果表明:牦牛血粉中含有一定量的游离氨基酸,其中包括8种人体必须氨基酸。无机元素以Al、Na、Mg、K、Ca、Fe为主,还含有V、Cr、Mn、Zn、Co、Ni、Cu、Se等人体所需微量元素,各无机元素均在浓度考察范围内,线性关系良好(r^2>0.9984),加样回收率在99.2%~108.4%之间。该研究初步明确藏药牦牛血粉饮片中氨基酸和无机元素的组成,方法准确高效,为综合评价藏药牦牛血粉饮片的质量提供科学依据和方法参考。     

卷烟制丝工艺的四要素管控要点探析

对现代卷烟生产企业而言,产品质量是其核心竞争力的重要体现,努力提高产品质量水平对企业生存与发展的重要性不言而喻。在卷烟生产过程中,制丝工艺流程最长,设备最多,操作最繁琐,制丝生产工艺是三大生产工序(制丝、卷接、包装)中的核心环节,它对提高卷烟内在品质、节约生产能源、降低焦油危害起着至关重要的作用。在该文中,笔者结合工作实践,围绕影响制丝工艺质量的四要素,针对其管控要点进行了较为系统的探析。     

液相色谱串联质谱法测定烟草中的游离氨基酸

建立液相色谱串联质谱法测定烟草中20种游离氨基酸的方法。烟草样品经0.1%的盐酸溶液超声萃取并离心后,直接进样测定。色谱柱采用XTerra MS C18(50mm×2.1mm×2.5μm),0.1%甲酸溶液和乙腈为流动相。结果表明:20种氨基酸的检出限为0.001～0.011μg/mL,标准曲线的拟合度均大于0.999,回收率在86.4%～105.9%之间。该方法操作简单,灵敏度高,适用于烟草中游离氨基酸的检测。     

UPLC-Q-TOF快速测定常见氨基酸含量

结合外标法或同位素稀释质谱法,建立UPLC-Q-TOF快速定量氨基酸分析方法。在无离子对试剂及衍生化情况下,实现对样品中氨基酸的快速测定。采用外标法测定时,14种常见氨基酸在其相应线性范围内,r2为0.953~0.999,LOD为0.001~0.080 mg/g,CV为1.4%~9.8%;采用Q-TOF外标法定量时,CV为1.5%~8.0%,误差为-9.1%~40%;采用同位素稀释质谱法测定各氨基酸浓度时,CV为1.4%~3.8%,误差为-3.4%~3.7%。本方法可在2min之内完成14种氨基酸的分离和定量,大大缩短分析时间。同时由于采用高分辨的飞行时间质谱,避免检测时离子间的相互干扰,提高测定结果的准确性,可用于蛋白质标准物质均匀性、稳定性检验及定量。     

柱前衍生与柱后衍生法检测紫芝药材中氨基酸

采用柱前衍生法和柱后衍生法测定紫芝药材中氨基酸成分,分析氨基酸分析仪(离子交换色谱分离-柱后衍生)和高效液相色谱仪(柱前衍生-反相液相色谱分离)在氨基酸测定上存在的异同。结果表明两种方法在测定同一样品时,在丝氨酸、异亮氨酸和脯氨酸等组分检测上的差异显著。     

氨基酸离子液体对壳聚糖溶解性能的影响

合成了一系列氨基酸类离子液体,从中筛选出对溶解壳聚糖具有良好性能的离子液体——甘氨酸盐酸盐离子液体。在常温常压下考察了该离子液体1%～10%水溶液对壳聚糖的溶解能力,溶解壳聚糖能力最大能达到6.32%(质量分数,下同)。对离子液体重复使用5次后,溶解能力没有明显下降。采用X射线衍射(XRD)和红外光谱(FT-IR)对再生的壳聚糖进行表征,结果表明,壳聚糖在溶解过程中没有发生衍生化。甘氨酸盐酸盐离子液体水溶液是壳聚糖的良溶剂。     

Amino acid analysis by capillary electrophoresis electrospray ionization mass spectrometry

A method for the determination of underivatized amino acids based on capillary electrophoresis coupled to electrospray ionization mass spectrometry (CE-ESI-MS) is described. To analyze free amino acids simultaneously a low acidic pH condition was used to confer positive charge on whole amino acids. The choice of the electrolyte and its concentration influenced resolution and peak shape of the amino acids, and 1 M formic acid was selected as the optimal electrolyte. Meanwhile, the sheath liquid composition had a significant effect on sensitivity and the highest sensitivity was obtained when 5 mM ammonium acetate in 50% (v/v) methanol-water was used. Protonated amino acids were roughly separated by CE and selectively detected by a quadrupole mass spectrometer with a sheath flow electrospray ionization interface. Under the optimized conditions, 19 free amino acids normally found in proteins and several physiological amino acids were well determined in less than 17 min. The detection limits for basic amino acids were between 0.3 and 1.1 mumol/L and for acidic and low molecular weight amino acids were less than 6.0 mumol/L with pressure injection of 50 mbar for 3 s (3 nL) at a signal-to-noise ratio of 3. This method is simple, rapid, and selective compared with conventional techniques and could be readily applied to the analysis of free amino acids in soy sauce.     

Content of amino acids and the quality of protein in Brussels sprouts,both raw and prepared for consumption

The aim of the investigation was to evaluate the content of amino acids and the quality of protein in Brussels sprouts. The investigation included the raw material, cooked sample and two types of frozen product stored at ?20 °C for 12 months and then prepared for consumption. The frozen products investigated were obtained using the traditional method (blanching before freezing) and the modified method (cooking before freezing, then defrosting and heating in microwave oven after refrigerated storage) of the ready-to-eat type. Brussels sprouts, both fresh and prepared for consumption, were a good source of protein and amino acids. Proline and glutamic acid were dominating; leucine and tyrosine with phenylalanine were limiting amino acids. The product obtained by modified method contained 16% less amino acids in 16 g N than the raw material and 14% less than the raw material after cooking, and also 10% lower than that of the traditionally obtained product.     

苏云金芽孢杆菌cry1Aa核心毒素基因转化烟草及其杀虫活性

将苏云金芽孢杆菌cry1Aa的C端编码区截短,获得编码N端609个氨基酸约1.8kb的核心毒素基因,将其构建到植物表达载体转化烟草,研究直接表达的活性ICP核心毒素被昆虫取食后的杀虫效果.T1代种子发芽的抗生素抗性分离和PCR检测证实cry1Aa核心毒素基因整合到了烟草基因组,Western 杂交检测表明转化烟草能够正常表达大小为75.6kD的核心毒素蛋白.生物测定结果表明,转化烟草对初孵棉铃虫平均有高于60%的致死率,对初孵甜菜夜蛾平均达到70%的致死率,最高致死率均可达到90%以上,并对昆虫的生长发育有明显的抑制作用.     

红树木榄胚轴基本化学组分研究

对红树植物木榄胚轴中的水分、灰分、灰分中的酸不溶物和硫化物、粗脂肪、粗蛋白及氨基酸和微量元素等一系列物质组分进行了系统的分析测定。结果显示:木榄胚轴中水分64.97%、灰分0.78%、灰分中酸不溶物0.0125%、灰分中硫化物化物0.2038%、粗脂肪0.9143%、粗蛋白3.43%;由木榄胚轴中测得了16种氨基酸,其总含量为25.005ug/g,其中人体必须氨基酸7种,占所含氨基酸总量约7.9%;在木榄胚轴中检测到了砷、钴、铬、铜、铁、镁、锰、镍、铅、硒、钛、钡、锶等13种元素,并测得了含量。     

Electrospray mass spectrometry: application of ion evaporation theory to amino acids

We describe the result of applying the ion evaporation theory to a series of amino acids. The very good correlation (r = 0.98) of the natural logarithms of protonated molecule intensities observed by electrospray with the difference between the hydration free energies of molecules and the gas-phase binding free energies of molecules and protons in amino acids is consistent with the ion evaporation model. It seems that the difference in the protonated molecule intensities of amino acids obtained by electrospray can be explained by a scheme in which protonated molecules in the liquid phase are extracted into the gas phase after a charged droplet is formed.     

Determination of Selected Perfluorinated Acids (PFCAs) and Perfluorinated Sulfonates (PFASs) in Food Contact Materials Using LC‐MS/MS

Perfluorinated compounds, including perfluorinated acids and perfluorinated sulfonates, are environmentally persistent. These compounds are commonly used in consumer products as stain/water/grease repellents in carpets and clothing, in cooking utensils as nonstick coating and in food contact materials as a coating. This paper explores the potential application of liquid chromatography coupled with tandem mass spectrometry (LC‐MS/MS) system for the measurement of selected perfluorinated acids and perfluorinated sulfonates in three different brands (A, B and C) of food contact materials, including wrapping papers, breakfast bags, baking papers and roasting bags. In this study, the highest contents of selected perfluorinated acids were identified for the breakfast bag samples (2.54–6.60 pg/cm²), especially for B and C brands with the concentration of 6.60 and 5.35 pg/cm², respectively, while the lowest content was noted in roasting bag samples (0.27–0.40 pg/cm²). The contents of perfluorinated sulfonates were inversed as compared with those of perfluorinated acids. The highest contents of selected perfluorinated sulfonates were found in roasting bag samples (1.38–5.17 pg/cm²), especially for B brand. The analysed perfluorinated sulfonates were not detected in any of the breakfast bag samples. The highest content of perfluorinated compounds were reported for B brand food contact materials. The data indicate a risk of food contamination by perfluorinated compounds from the commonly used food contact materials. Copyright © 2015 John Wiley & Sons, Ltd.