Determination of both jasmonic acid and methyl jasmonate in plant samples by liquid chromatography tandem mass spectrometry

An efficient method for the simultaneous extraction and quantification of both jasmonic acid (JA) and methyl jasmonate (MeJA) from a single plant sample was developed. Plant tissues were firstly extracted by using 100% cold methanol, then the Sep-pak C₁₈ solid-phase extraction (SPE) cartridges were adopted for the purification of sample extract, and finally JA and MeJA were deter-mined by the liquid chromatography tandem mass spectrometry (LC-MS-MS) system. It was found that the accuracy was improved by using the extra standard for the estimation and correction of JA and MeJA losses in the extraction and purification process. The detection limits for JA and MeJA were 0.03 and 0.075 ng mL⁻¹, respectively, and the average recovery rate of JA and MeJA was 92.48% and 94.30%. The method was found to be reproducible and selective, yielding well isolated and easily detectable peaks for both JA and MeJA and simplifying the time-consuming extraction and purification. High-performance liquid chromatography (HPLC) system was employed as the control detection method for the LC-MS-MS system. The two systems were compared in their specificity and accuracy.     

V (Ⅴ)-KIO4-甲基红体系动力学光度法测定微量钒

研究了在柠檬酸介质中,钒(Ⅴ)强烈地催化高碘酸钾氧化甲基红的褪色反应,建立了催化动力学光度法测定微量钒(Ⅴ)的方法.钒质量浓度在0.64～3.20 μg/mL范围内与log(A₀/A)呈线性关系,检出限为3.75×10^-3 μg/mL.该方法用于提钒废水中钒的测定,结果满意.     

椰子油为原料酶法制备脂肪酸甲酯

以椰子油为原料利用固定化Candida antarctica sp.99-125脂肪酶转酯化制备了脂肪酸甲酯。分析了椰子油的脂肪酸组成,并测定了椰子油平均分子量,考查了关键因素对反应的影响及反应历程。实验结果表明:椰子油平均分子量为655.27;最优反应条件为:酶最小加入量为20%,水加入量为15%,正己烷加入量为4mL/2 g椰子油。此反应条件下原料油转化率达到90%。     

氰乙酸甲酯的合成

提高减压蒸馏氰乙酸水溶液的水浴温度,并在氰乙酸与甲醇在酸性条件下回流后采用加苯除水,再加浓硫酸回流的方法,使氰乙酸甲酯的摩尔产率达到85%以上.     

用冠醚催化的黄鸣龙改进法合成胆石酸

以来源丰富的猪去氧胆酸甲酯(Ⅳ)为原料,经选择性氧化得C_6—酮(V),产率64％.将C_6—酮与水合肼反应成腙后加入18—冠—6和KOH分解腙,制得了胆石酸(Ⅶ),产率70％.     

Involvement of Jasmonate-signaling pathway in the herbivore-induced rice plant defense

The expression patterns of eight defense- related genes in the herbivore-infested and jasmonate- treated (jasmonic acid, JA and its derivative MeJA) rice leaves were analyzed using RT-PCR. The results showed that Spodoptera litura Fabricius (Lepidoptera: Noctuidae) herbi-vory induced the expression of lipoxygenase (LOX) and al-lene oxide synthase (AOS) genes that are involved in the jasmonate-signaling pathway. Moreover, S. litura damage resulted in the expression of farnesyl pyrophosphate syn-thase (FPS), Bowman-birk proteinase inhibitor (BBPI), phenylalanine ammonia-lyase (PAL) and other rice defense- related genes that were also induced by aqueous JA treat-ment or gaseous MeJA treatment. These indicated that in rice leaves, the JA-related signaling pathway was involved in the S. litura-induced chemical defense. Mechanical damage and brown planthopper (BPH), Nilaparvata lugens (St錶) (Homoptera: Delphacidae) damage induced the expression of LOX gene, but both treatments did not induce the expression of AOS gene. However, BPH damage induced the expression of acidic pathogen-related protein 1 (PR-1a), Chitinase (PR-3), and PAL genes, which is involved in the salicylate- signaling pathway. It was suggested that salicylate-related signaling pathway or other pathways, rather than jas-monate-signaling pathway was involved in the BPH-induced rice plant defense.     

芳叔胺体系引发乙烯类单体聚合的机理——自旋捕集ESR法

采用自旋捕集ESR技术和紫外光谱法,研究了N,N-二甲基苯胺(DMA)-苄基氯(BC)引发甲基丙烯酸甲酯(MMA)自由基聚合的机理;DMA对MMA、丙烯酸甲酯(MA)、苯乙烯(St)及α-甲基苯乙烯(α-MeSt)烯类单体的引发作用。在60℃、无氧条件下、DMA-BC-MMA体系中可产生自由基其中仅有R3参与引发反应,由此证实了以前所提出的引发机理。DMA单独存在下与MMA、α-MeSt这些带有α-甲基的乙烯类单体也可形成活泼的自由基R3,并引发聚合;若与不带有α-甲基的乙烯类单体,如MA、St,则不能形成自由基R3,因此它们不能被引发聚合。     

“Cr~(2+)+BPO”体系引发的活性自由基聚合

以“Cr~(2+)+BPO”体系,在0～40℃下,引发了一系列烯类单体的聚合。该体系引发的活性自由基聚合反应对单体结构有如下的选择性:α-甲基丙烯酸酯类单体在不高于30℃时能进行活性自由基聚合;其它烯类单体,如丙烯酰胺、丙烯腈、苯乙烯以及α-碳原子上不带甲基的丙烯酸酯类单体,均不能进行;而丙烯酸和α-甲基苯乙烯则不能被引发聚合。当温度高于30℃时,α-甲基丙烯酸酯类单体只能进行一般的自由基聚合。根据聚合结果,讨论了该体系引发活性自由基聚合反应的机理。利用“Cr~(2+)+BPO”体系,使MMA与丙烯腈进行嵌段共聚,共聚产物经分离,得到了较纯的嵌段共聚物,并予以表征。采用ESR和可见光谱,探讨了“Cr~(2+)+BPO”体系陈化反应的机理。