顶空毛细管气相色谱法测定异丙托溴铵中7种残留有机溶剂

目的: 建立顶空毛细管气相色谱法, 测定异丙托溴铵中甲醇?丙酮?异丙醇?二氯甲烷?乙酸乙酯?三氯甲烷?甲苯等7 种有机溶剂残留量。方法: 色谱柱:DM-624( 聚乙二醇PEG-20M) 毛细管柱(30.0m×0.53mm,3.00μm)；载气: 氮气, 流速为2.0mL·min-1；柱温:程序升温, 初始温度为40℃ , 保持5min, 然后以6℃·min-1 升温到150℃ , 再以50℃·min-1 升温到230℃ , 保持3min；检测器: 氢火焰离子化检测器, 温度为250℃；进样口温度:240℃；顶空进样量:1.0mL。结果: 甲醇?丙酮?异丙醇?二氯甲烷?乙酸乙酯?三氯甲烷和甲苯分别在15.02~900.92mg·L-1(r=0.9999)、21.03~1262.00mg·L-1(r=0.9999)、21.30~1278.16mg·L-1(r=0.9999)、7.80~468.25mg·L-1(r=0.9998)、22.22~1332.97mg·L-1(r=0.9999)、0.31~18.79mg·L-1(r=0.9992) 和3.48~209.02mg·L-1(r=0.9998) 范围内线性关系良好,平均回收率分别为98.1%(RSD=0.19%)、100.1%(RSD=1.08%)、101.4%(RSD=1.03%)、98.1%(RSD=0.40%)、98.1%(RSD=1.55%)、98.9%(RSD=3.08%) 和101.8%(RSD=2.12%)。结论: 该方法简便?灵敏?重复性好, 结果准确, 适用于异丙托溴铵中残留有机溶剂的检测。     

A setup for incubating plant cultures under continuous flow of gases

Summary This note describes a simple experimental system for incubating plant cell and tissue cultures under conditions in which the gaseous environment within the culture flasks is continuously flushed out by air or gas mixtures of known composition. Two of the major problems in maintaining such cultures, namely, contamination and desccation of the agar-solidified medium, can be overcome by using this setup. Furthermore, with modifications, it can be adapted for commercial micropropagation projects. This research was supported by Natural Sciences and Engineering Research Council of Canada grant A-6467 to T. A. Thorpe. The authors thank R. W. Joy IV for drawing Fig. 1B.     

Identification of sulcatol, a potential pheromone of the ambrosia beetle Gnathotrichus materiarius (Col., Scolytidae)

Abstract: We report the identification of a potential pheromone for Gnathotrichus materiarius (Fitch) (Col., Scolytidae). The population sex ratio is close to 1 : 1, and males initiate attacks on host trees. Headspace and hindgut samples from single males showed the presence of the putative pheromone 6-methyl-5-hepten-2-ol, sulcatol. Unmated males released sulcatol for at least 12 days, and ceased producing the pheromone after 20 days. The peak sulcatol release occurred after 2 days. Males cease production of sulcatol 24 h after being paired with females. Single females were unable to initiate galleries, and no sulcatol was detected from their headspace and hindgut samples. The chiral ratio of the pheromone, observed from headspace samples, was 31% (S)-(+)- and 69% (R)-(−)-sulcatol.     

Practical approaches to plant volatile analysis

Plants emit volatile organic compounds (VOCs) that play important roles in their interaction with the environment and have a major impact on atmospheric chemistry. The development of static and dynamic techniques for headspace collection of volatiles in combination with gas chromatography-mass spectrometry analysis has significantly improved our understanding of the biosynthesis and ecology of plant VOCs. Advances in automated analysis of VOCs have allowed the monitoring of fast changes in VOC emissions and facilitated in vivo studies of VOC biosynthesis. This review presents an overview of methods for the analysis of plant VOCs, including their advantages and disadvantages, with a focus on the latest technical developments. It provides guidance on how to select appropriate instrumentation and protocols for biochemical, physiological and ecologically relevant applications. These include headspace analyses of plant VOCs emitted by the whole organism, organs or enzymes as well as advanced on-line analysis methods for simultaneous measurements of VOC emissions with other physiological parameters.     

Headspace-solid-phase microextraction fast GC in combination with principal component analysis as a tool to classify different chemotypes of chamomile flower-heads (Matricaria recutita l.)

Headspace-solid-phase microextraction gas chromatography-principal component analysis (HS-SPME GC-PCA) is proposed as a complementary or alternative method to essential oil (EO) GC-PCA in order to discriminate between flower-heads of chamomile of different chemotypes. Ninety-two EOs and the headspaces sampled by HS-SPME of the corresponding chamomile flower-heads were examined by conventional GC and fast GC (F-GC) and the results submitted to statistical analysis by PCA. HS-SPME F-GC-PCA showed itself to be a rapid technique by which to distinguish chamomile flower-head chemotypes a produced results in agreement with the accepted EO classification. Using this method, the analysis time was reduced from at least 4.5 h with EO conventional GC to less than 1 h with HS-SPME F-GC. This approach can thus successfully be used as an analytical decision maker in order to reduce the number of time-consuming EO conventional GC analyses by limiting them to those samples that cannot unequivocally be classified. The EO conventional GC and HS-SPME F-GC results of PCA were very uniform, but they did not provide quantitative correlations between the components as determined by the two methods. A different statistical approach and a larger number of samples will be needed in order to correlate components in the headspace sampled by SPME and those in the corresponding EO quantitatively through a function.     

Floral scent diversity is differently expressed in emitted and endogenous components in Petunia axillaris lines

BACKGROUND AND AIMS: Among the subspecies of Petunia axillaris are various lines emitting sensorially different scents. Analysis of variations in floral scent among genetically close individuals is a powerful approach to understanding the mechanisms for generating scent diversity. METHODS: Emitted and endogenous components were analysed independently to gain information about evaporation and endogenous production in 13 wild lines of P. axillaris. A dynamic headspace method was used to collect emitted components. Endogenous components were extracted with solvent. Both of these sample types were subjected to quantitative and qualitative analysis by gas chromatography (GC)-flame ionization detector (FID) and GC-mass spectrometry (MS). KEY RESULTS AND CONCLUSIONS: Whereas the profiles of emitted compounds showed qualitative homogeneity, being mainly composed of methyl benzoate with quantitative variation, the profiles of endogenous compounds showed both qualitative and quantitative variation. A negative correlation was found between the evaporation ratio and boiling point of each compound examined. Lower boiling point compounds were strongly represented in the emitted component, resulting in the reduction of qualitative variation in floral scent. In conclusion, floral scent diversity results from variation in both the endogenous production and the evaporation rate of the individual volatile compounds.     

Flower scents from the Pacific

For a long time, exotic scents from the islands of the South Pacific have universally been appreciated. Most frequently, fragrant flowers (e.g., frangipani, jasmine sambac, tiaré, pua kenikeni) are used locally for ornamental purposes such as flower garlands (leis). Despite their powerful and delightful fragrance, very few of these flowers have been commercially employed in this part of the world for perfume manufacturing. Creative perfumers are nevertheless strongly interested to better understand these fragrances and to use them, either genuine or artificially reconstituted. Analytical results on the fragrance of these flowers are reported, together with some economical considerations.     

Floral scents in butterfly-pollinated plants: possible convergence in chemical composition

The study explores whether or not there are convergent patterns in floral scent composition among plant species that completely or partially rely on butterflies for pollination. Floral scent compounds were analysed from 22 flowering butterfly-pollinated plant species, representing 13 families which originate mainly from temperate North Europe but also from tropical and temperate America. Scents were collected using the dynamic headspace adsorption method and identified with coupled gas chromatography and mass spectrometry (GC-MS). In total, 217 floral scent compounds were identified, with the number per species ranging from 8 to 65. The major emerging pattern is the occurrence of certain compounds emitted exclusively by the flowers of many of the investigated species in major amounts – the benzenoids phenylacetaldehyde and 2-phenylethanol, the monoterpenes linalool and linalool oxide (furanoid) I and II and the irregular terpene oxoisophorone. It is likely that these compounds serve as a signal to attract pollinating butterflies, and may have evolved in conjunction with the sensory capabilities of butterflies as a specific group of pollinators. While there is convergence in terms of the compounds sharing this function there has been a geographical divergence in terms of their relative abundance. The predominance (in terms of both numbers and relative amount) of benzenoids in many of the scent blends of the European temperate species and of linalool and its derivatives in those of the American species constitute two discernible groups among these plants.  © 2002. The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 129–153.     

Host selection by Ibalia leucospoides based on temporal variations of volatiles from the hosts’ fungal symbiont

Insect parasitoids locate hosts via reliable and predictable cues such as volatile emissions from hosts and/or host plants. For insects that depend on mutualistic organisms, such as many wood‐boring insects, symbiont‐derived semiochemicals may represent a source of such cues to be exploited by natural enemies. Ultimately, exploitation of these signals may increase fitness by optimizing foraging efficiency. Female parasitoids of Ibalia leucospoides use volatiles from the fungal symbiont Amylostereum areolatum of their host Sirex noctlio to find concealed host eggs and young larvae within the xylem. We hypothesize that the temporal pattern of fungal emissions may indicate not only the presence of host larvae but also be used as a cue that indicates host suitability and age. Such information would allow female parasitoids to discern more efficiently between hosts within ovipositor reach from those already buried too deep into the xylem and out of reach. In this context, we assessed the behaviour of I. leucospoides females to volatiles of A. areolatum in a ‘Y’‐tube olfactometer at regular intervals over 30 days. We concurrently examined the fungal volatiles by headspace sampling through solid‐phase microextraction (SPME) followed by gas chromatography mass spectrometry (GC‐MS). We observed that females were attracted to volatiles produced by two‐week‐old fungal cultures, a period that matches when older larvae are still within ovipositor reach. Four chemical compounds were detected: ethanol, acetone, acetaldehyde and the sesquiterpene 2,2,8‐trimethyltricyclo[6.2.2.01,6]dodec‐5‐ene, with each compounds’ relative abundance changing over time. Results are discussed in the context of parasitoids fitness. Future studies involving electrophysiology, different collection techniques and further behavioural assays will help in identifying the compounds that convey temporal information to female parasitoids and have the potential for being used in integrated pest management programmes.