盐酸浸提-电感耦合等离子体发射光谱法测定烟草中的多元素

研究了用5mol/L盐酸煮沸提取烟叶中的部分金属元素，用ICP－AES测定浸提液，K、Ca、Mg、Cu、B、Ba、Zn获得了较满意的结果，P、Fe、Mn的测定结果稍微偏低。此方法操作简便、快速安全，特别适合大批量烟草样的快速检测。与硝酸－高氯酸湿消化法进行对照，结果吻合得较好。并测定了国家烟草标准样品GBW08514和GBW08515，其结果与标准值相符。     

一种基于分子信标荧光探针快速检测烟草花叶病毒的新方法

研究了一种利用新型荧光探针——分子信标进行植物病毒检测的方法，可以不要求对病毒RNA进行严格的分离和纯化，就能快捷地得到检测结果。此方法被用于烟草花叶病毒(tobacco mosaic virus，TMV)基因组RNA的检测，为植物病毒分子生物学的研究提供了新的手段。     

烟草三维荧光特征和品质评吸的关系

研究不同品种烟草石油醚冷萃取物的三维荧光光谱，包括烟草所共在的荧光性质和各自的荧光特性，寻找它们与烟草香味，颈头等吃味之间的关系，选择合适的量值指标，为烟草品质的 观感官评估提供了一个实用的对照方法。     

Direct electrochemistry of recombinant tobacco peroxidase on gold

Direct electron transfer (DET) reactions of recombinant tobacco peroxidase (rTOP), namely direct electroreduction of Compound I/Compound II and heme Fe^3+/2+ conversion, were studied on gold electrodes. rTOP of wild type, non-glycosylated, was produced using an Escherichia coli expression system. At pH 5.0, the redox potential for direct electrochemical transformation of the Fe^3+/2+ of the peroxidase heme was −143 mV vs. AgAgCl, and 0.26 ± 0.07 pmol of the adsorbed rTOP were in DET contact with the gold electrode. The total amount of the adsorbed rTOP estimated from QCM data was 53 ± 5 pmol/cm² or 1.67 pmol when referred to the surface area of the electrodes used for electrochemical measurements. Of 1.67 pmol of adsorbed rTOP, only 0.76 pmol were catalytically active. DET between Au and the enzyme was also studied in the reaction of the bioelectrocatalytic reduction of H₂O₂ by cyclic voltammetry and amperometric detection of H₂O₂ at +50 mV with rTOP-modified Au electrodes placed in a wall-jet flow-through electrochemical cell. Maximal bioelectrocatalytic current response of the rTOP-modified gold electrodes to H₂O₂ was observed at pH 5.0 and stemmed from its bioelectrocatalytic reduction based on DET between Au and the active site of rTOP. Kinetic analysis of the DET reactions gave 52% of the adsorbed rTOP molecules active in DET reactions (0.4 pmol of adsorbed catalytically active rTOP, correspondingly), which correlated well with the non-catalytic-voltammetry data. DET was characterised by a heterogeneous ET rate constant of 13.2 s⁻¹, if one takes into account the QCM data, and 19.6 s⁻¹, if the amount of rTOP estimated from the data on DET transformation of Fe^3+/2+ couple of rTOP is considered. The sensitivity for H₂O₂ obtained for the rTOP-modified Au electrodes was 0.7 ± 0.1 A M⁻¹ cm⁻². These are the first ever-reported data on DET reactions of anionic plant peroxidases on bare gold electrodes.     

铜离子对烟草多酚氧化酶变性和复性影响的热力学研究(英)

在有无5 mmol·L^-1 CuSO₄存在的两种情况下，运用荧光光谱研究了烟草多酚氧化酶在盐酸胍诱导下的变性和复性平衡。烟草多酚氧化酶在6.0 mol·L^-1盐酸胍变性30 min(25 ℃)即完全失活。荧光光谱结果表明：铜离子能够提高烟草多酚氧化酶的结构稳定性和抗盐酸胍变性的能力，进而影响烟草多酚氧化酶在盐酸胍诱导下的变性和复性过程。没有外源铜存在的情况下，盐酸胍诱导的烟草多酚氧化酶变性和复性是一个可逆的二态过程；在5 mmol·L^-1 CuSO₄存在的条件下，由于结合了Cu²⁺的酶的中间态稳定性增加，显示特征荧光，结果显示，外源铜存在时，盐酸胍诱导的烟草多酚氧化酶变性和复性是一个可逆的三态过程。根据相应模型，进行了热力学计算。上述实验结果得到酶活性测定的进一步证实，在6 mol·L^-1盐酸胍中放置5，10，15，20，25，30 min，烟草多酚氧化酶的剩余活性分别为18.7%，11.7%，8.9%，6.6%，3.6%，0.06%，但在5 mmol·L^-1 CuSO₄存在的条件下，剩余活性则分别为60.3%，44.6%，42.5%，40.2%，25.6%，25.3%。     

Simultaneous quantification of ten Amadori compounds in tobacco using liquid chromatography with tandem mass spectrometry

Amadori compounds are aroma precursors formed in the initial phase of the Maillard reaction. Based on their similar structures, simultaneous quantification of more than six Amadori compounds in tobacco has not been reported yet. In this study, a simple and rapid method was developed to simultaneously quantify ten Amadori compounds including the isomers of Fructose‐isoleucine and Fructose‐leucine in tobacco. The separation was performed on an Atlantis T₃ column (2.1 × 250 mm, 5 μm) by gradient elution using acetonitrile and water as the mobile phases. The quantification method was systematically evaluated and proven to be sensitive and accurate. The linearity was good, with correlation coefficients of 0.9977–0.9999. The limits of detection and quantitation were 1.354–2.532 and 4.516–8.444 ng/mL, respectively. The recoveries were 84.0–119.6%, and the relative standard deviations were 1.33–5.40%. The method was used to analyze the changes in the amounts of ten Amadori compounds in tobacco before and after tobacco primary processing. The analysis shows that the Maillard reaction occurs during the short processing period.     

Simultaneous determination of residues of metalaxyl,cyazofamid and a cyazofamid metabolite in tobacco leaves and soil by liquid chromatography with tandem mass spectrometry

A simple method was developed and validated for the simultaneous determination of metalaxyl, cyazofamid and the cyazofamid metabolite 4‐chloro‐5‐p‐tolylimidazole‐2‐carbonitrile (CCIM) by liquid chromatography with tandem mass spectrometry. The three target compounds were extracted from tobacco and soil with acetonitrile containing 0.1% acetic acid, and the extracts were purified using octadecylsilane. The proposed method showed satisfactory linearity (R² ≥ 0.9985) for the target compounds. The limits of detection for metalaxyl, cyazofamid and CCIM were 0.006, 0.06 and 0.06 mg/kg in soil and green tobacco leaves and 0.03, 0.3 and 0.3 mg/kg in cured tobacco leaves, respectively. The limits of quantification for metalaxyl, cyazofamid and CCIM were 0.02, 0.2 and 0.2 mg/kg in soil and green tobacco leaves and 0.1, 1 and 1 mg/kg in cured tobacco leaves, respectively. The average recoveries from soil and tobacco were 72.91–98.40% for metalaxyl, 76.73–105.80% for cyazofamid and 74.48–106.45% for CCIM. The relative standard deviation range was 1.23–6.99%. The developed method was successfully applied to analysis of residues of metalaxyl, cyazofamid and CCIM in real soil and tobacco samples. The results indicated that the established method could meet the requirement for the analysis of trace amounts of all three analytes in soil and tobacco.     

Two New 4‐Hydroxyisoflavanes from the Root of Codonopsis cordifolioidea and Their Anti‐virus Activities

Two new 4‐hydroxyisoflavanes, cordifoliflavanes A and B (1 and 2), were isolated from the roots of Codonopsis cordifolioidea. Their structures were elucidated by spectroscopic methods, including extensive 1D‐ and 2D‐NMR techniques. Compounds 1 and 2 were tested for their anti‐HIV‐1 activities and anti‐tobacco mosaic virus activities. The results showed that compounds 1 and 2 have modest anti‐HIV‐1 activities and anti‐tobacco mosaic virus activities, respectively.     

Quantitation of perfluoroalkyl acids,parabens and cotinine from single low volume serum sample by validated analytical method

ABSTRACT

In this paper, we present the results of an analytical method that has been recently developed, validated and successfully applied in a biomonitoring approach. In the environmental pollutant studies it is desirable that the analytical method can determine multiple classes of compounds from a single, small volume sample. The presented analytical method with a simple sample pre-treatment allows the quantitation of 13 perfluoroalkyl acids (PFAAs), 6 parabens and cotinine (used as nicotine biomarker) from a single, small volume of 100 µL serum sample by liquid chromatography-triple quadrupole mass spectrometer (LC-MS/MS). The limits of quantitation (LOQ) for PFAAs, parabens and cotinine were 0.10–0.50, 0.20–0.80 and 0.10 ng/mL, respectively. Besides sensitivity the method has excellent trueness/accuracy and repeatability. The trueness of the method for the determination of PFAAs ranged from 95% to 106% and the repeatability (as RSD %) from 0.6% to 5.6%. The accuracy and RSD for parabens were 73–120% and 1.3–9.7%, respectively, and 100–106% and 1.3–3.5 % for cotinine. Biomonitoring data reveals the presence of several PFAAs and parabens in serum samples of Finnish population. The total concentrations for PFAAs and parabens were from 2.0 to 33 ng/mL and from <LOQ to 1100 ng/mL, respectively. Nearly all non-smokers had the serum cotinine concentration below 1.0 ng/mL, which can be suggested as the cut point for cotinine concentration to identify smoking.     

烟草热解残余物中自由基的分析

使用顺磁共振波谱技术研究了烟草热解残余物中自由基的形成及其在环境中的转化。研究结果表明:烟草热解时会在其残余物上形成大量自由基。热解温度较低时(400~500℃)主要形成以O原子为中心的自由基,而热解温度较高(600~700℃)时,主要形成以C原子为中心的自由基。烟草热解残余物与空气接触后,会生成新的以O原子为中心的自由基,从而使自由基数量在短时间(60~120 min)内增加,随后自由基数量和种类趋于稳定,并可长期存在于环境中。