Quantitative solid phase microextraction – Gas chromatography mass spectrometry analysis of five megastigmatrienone isomers in aged wine

Megastigmatrienone is a key flavor compound in tobacco. It has also been detected in wine, where it may contribute to a tobacco/incense aroma, but its importance and concentration in wines had never previously been evaluated.     

4-(2-羟基-4-硝基苯偶氮)-1-苯基-3-甲基吡唑啉酮光度法测定烟草中镁

研究了 4 - (2 -羟基 - 4-硝基苯偶氮 ) - 1-苯基 - 3-甲基吡唑啉酮 (HNAPMP)与镁的显色反应 ,在 p H=10的硼砂 -氢氧化钠缓冲介质中 ,HNAPMP与镁反应生成 2∶ 1稳定络合物 ,λmax=5 2 2 nm,ε=3.5 8× 10 4L·mol-1· cm-1。镁含量在 0— 2 0 μg/2 5 m L范围内符合比耳定律 ,方法用于烟草样品中镁含量的测定 ,结果令人满意     

Statistical mixture design investigation of fractionated and total extracts from Erythrina speciosa Andrews leaves

The simplex centroid mixture design for the ethanol, dichloromethane, hexane and acetone solvents has been applied to the extraction of crude mass and the fiber, organic, neutral and basic fractions as well as the fractionation residues of Erythrina speciosa Andrews leaves. Binary and ternary synergic solvent interactions are seen to provide dominant contributions to the extraction of both crude mass and all the fractions. Quadratic and special cubic mixture models precisely predict the extracted quantities of each fraction and the residue as a function of the proportions of the four solvents. Different solvent mixtures are found to be the most efficient extractors for the different fractions: binary dichloromethane‐hexane mixtures for the fiber fraction, ternary ethanol‐dichloromethane‐acetone mixtures for the neutral fraction, binary ethanol‐dichloromethane mixtures for the organic fraction, crude extract and residue values and ternary ethanol‐dichloromethane‐hexane mixtures for the basic fraction. Principal component analysis shows that the ethanol‐dichloromethane mixtures are important for extracting large quantities of the basic and organic fractions as well as of the residue and crude masses.     

EDXRF spectrometry determination of tungsten in tobacco plants after antiviral treatment with 12-tungstophosphoric acid and its compounds

In this study, we have developed a sensitive, rapid and simple procedure for the energy dispersive X-ray fluorescence (EDXRF) spectrometry measurement of tungsten in tobacco plant parts. Only 0.1 g of dried plant material is needed instead of the usual 1 g. EDXRF spectrometry is used for quantitative measurement, after the foliar application of solutions of tungstophosphoric acid (WPA), its magnesium salt and compounds with glycine (Gly) and alanine (Ala), in exact quantities. After that, the leaves, trunks and summits were collected and prepared separately. Tungsten is determined directly in raw dried material, and the overlap of the tungsten peak with zinc's that is present is avoided by the spectral deconvolution to obtain quantitative results. The prepared dry tablets weighed 100 mg, and measurement time was 2000 s. The radioisotope excitation source used was ¹⁰⁹Cd and tungsten was identified and quantified at the L_α1 and L_α2 lines at the energies of 8397.6 eV and 8335.2 eV, respectively. EDXRF spectrometry was applied in a wide range of concentrations (up to 2000 mg/kg), with an estimated detection concentration limit of 15 mg/kg, calculated on dried material. Quantitative analysis of different parts of the treated plant plus the washings gave 94.47% recovery of the applied tungsten in different compound forms. After the foliar application of investigated WPA compounds, there were noticed both vertical and horizontal distributions of tungsten through out the tobacco plants, according to the EDXRF spectrometry results. This conclusion is also in agreement with the positive effects of WPA on Tobacco mosaic tobamovirus (TMV) infection of Nicotiana tabacum (Solanaceae).     

Mechanical damage and thermal effect induced by ultrasonic treatment in olive leaf tissue. Impact on polyphenols recovery

The influence of ultrasound treatment (US) on cellular damage of olive leaf tissue was studied. Mechanical damage and thermal effect of US were characterized. The level of tissue damage was defined by the diffusivity disintegration index Z_D based on the diffusivity of solutes extracted from olive leaves differently treated. The Arrhenius form using the temperature dependences of the thermal treatment time within the temperature interval 20–90 °C was observed for the thermal process. The corresponding activation energy ΔUT was estimated as 57 kJ/mol. The temperature dependences of electrical conductivity were measured for extracts of intact and maximally treated olive leaves. Then the diffusivity disintegration index Z_D and total phenolic compounds recovery for three studied US powers were calculated (100, 200, and 400 W). The results evidenced that the mechanically stimulated damage in olive leaf tissue can occur even at a low US power of 100 W if treatment time is long enough (t = 3.5 h). The US treatment noticeably accelerated the diffusion process mechanically in addition to its thermal effect. Trials in aqueous solution revealed the dependence of polyphenols extraction on damage level with respect to the US power applied.     

不同介质对轮轨增黏与磨损特性影响

利用MMS-2A摩擦磨损试验机研究了水介质下砂、氧化铝、研磨子对轮轨增黏与磨损特性影响.结果表明:干态和水介质下随蠕滑率增大黏着系数呈先增加后小幅降低并趋于稳定.水介质下氧化铝介质的增黏效果最好,研磨子最差;砂介质使轮轨磨损严重且塑性流变层最厚,轮轨试样表面剥落严重;氧化铝介质下轮轨磨损量较砂介质小,塑性流变层轻微;研磨子介质下的轮轨试样磨损量最小,磨损表面较为光滑;落叶显著降低黏着系数,且易形成落叶浆,使接触表面产生划痕;落叶工况下撒砂能增加黏着系数且能去除落叶浆,但易造成轮轨试样的剥落损伤.     

苹果树叶片叶绿素含量高光谱估测模型研究

叶片叶绿素含量是评估果树长势和产量的重要参数,实现快速、无损、精确的叶绿素含量估测具有重要意义。本研究以山东农业大学苹果园为试验区,采用高光谱分析技术探索苹果树叶片叶绿素含量的估测方法。通过分析叶片高光谱曲线特征,对原始光谱分别进行一阶微分、红边位置以及叶面叶绿素指数(LCI)变换,分别将其与叶绿素含量进行相关分析及回归分析,建立叶绿素含量估测模型并进行检验,从中筛选出精度最高的模型。结果显示,以LCI为变量的估测模型以及以一阶微分521和523nm组合为变量的估测模型拟合精度最高,决定系数R2分别为0.845和0.839,均方根误差RMSE分别为2.961和2.719,相对误差RE%分别为4.71%和4.70%。因此LCI及一阶微分是估测苹果树叶片叶绿素含量的重要指标。该模型对指导苹果树栽培生产具有积极意义。     

固相萃取-高效液相色谱法测定烟叶中吡虫啉农药残留量

建立了固相萃取-高校液相色谱法测定烟叶中吡虫啉农药残留量的方法。样品用乙腈提取,弗罗里硅土固相萃取柱净化.梯度洗脱方式分离,DAD二极管阵列检测器检测。吡虫啉加标回收率为87.83%—94.80%,相对标准偏差为1.64%,检出限为0.01μg/g。该方法灵敏、准确,适用烟草中吡虫啉农药残留的分析。     

同一种前处理方法测定烟草中砷、铅和镉

采用同一种前处理方法即硝酸和高氯酸消解处理烟草样品后,氢化物发生-原子荧光光谱法测定烟叶中砷、铅;原子吸收光谱法测定烟叶中镉。样品溶液介质为10%的盐酸,对7个样品平行3次重复实验,其相对标准偏差为砷:0.81%—4.96%、铅:2.82%—5.83%、镉:0.96%—4.60%,砷、铅、镉的检测线性范围分别为:0.0—120.0、0.0—60.Oμg·L^-1和0.0—800.0μg·L^-1,加标回收率:砷在94.5%—96.9%之间、铅在92.7%—101.6%之间、镉在102.2%—110.9%之间。     

对乙酰基偶氮氯膦光度法测定烟草中钙的方法研究

研究了对乙酰基偶氮氯膦 ( ACCPP)与钙的显色反应 ,在 p H=8.5的氯化铵 -氨水缓冲介质中 ,乳化剂 - OP存在下 ,ACCPP与钙反应生成 1∶ 1稳定络合物 ,λmax=680 nm,ε=4 .0 1× 10 4 L· mol-1· cm-1。钙含量在 0— 2 0μg/2 5m L范围内符合比耳定律 ,方法用于烟草样品中钙含量的测定 ,结果令人满意。