Chemical composition of essential oil of Senecio coincyi, an endemic species of the Central Iberian Peninsula

The essential oil has been studied of leaves of Senecio coincyi Rouy, an endemic species of Spain restricted to a very small area of the Central Iberian Peninsula. Samples from five locations were obtained by hydrodistillation and extraction and analysed by gas chromatography-mass spectrometry. The main compound was 1-tridecene (28.1 +/- 8.5%). The presence of unsaturated hydrocarbons (1-undecene, 1-dodecene and 1-tridecene) seems to indicate a chemotaxonomic relationship between Senecio coincyi and S. congestus.     

Quantitative 1h fourier transform nuclear magnetic resonance spectroscopic analysis of mixtures of pyrrolizidine alkaloids from senecio vulgaris

Summary An analytical method was developed in order to obtain qualitative and quantitative information on pyrrolizidine alkaloid mixtures from Senecio vulgaris L. (Compositae) by means of ¹H Fourier Transform Nuclear Magnetic Resonance spectroscopy. It was found that this plant contains not only seneciphylline, senecionine and retrorsine, but also the corresponding geometrical E-isomers spartioidine, integerrimine and usaramine. Some general instrumental conditions necessary for quantitative FT NMR were established, which enabled us to determine the total alkaloid level, the N-oxide level, the total Z/E ratio, and the amount of each Z/E isomer pair with good precision. The possibilities of using this method to analyze pyrrolizidine mixtures from other Senecio sp., and some advantages and limitations of quantitative analysis by means of ¹H FT NMR are discussed.

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Quantitative Analyse von Gemischen von Pyrrolizidinalkaloiden aus Senecio vulgaris mit Hilfe der ¹H-Fourier-Transform-KMR-Spektroskopie

Zusammenfassung Mit Hilfe der entwickelten Methode konnte festgestellt werden, daß diese Pflanze nicht nur Seneciphyllin, Senecionin und Retrorsin enthält, sondern auch die entsprechenden geometrischen E-Isomeren Spartioidin, Integerrimin und Usaramin. Die notwendigen apparativen Bedingungen wurden festgelegt und erlaubten die Bestimmung des Gesamtalkaloidgehaltes, des N-oxidgehaltes, des Gesamtverhältnisses Z/E sowie des Gehaltes an jedem Z/EIsomerenpaar mit guter Genauigkeit. Die Möglichkeit zur Anwendung des Verfahrens auch für andere Senecio-Arten sowie die Vorteile und Grenzen der ¹H-FT-KMR-Analyse werden diskutiert.

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Dedicated to Prof. Dr. E. Stahl on the occasion of his 60th birthday     

GC/MS analysis of the essential oil of Senecio belgaumensis flowers

The essential oil composition of the flowers of Senecio belgaumensis (Wight) Cl. was analyzed by gas chromatography and gas chromatography/mass spectrometry. Forty eight compounds were identified, representing 91.5% of the total oil. The main constituents were 1-undecanol (19.5%), beta-caryophyllene (18.9%), caryophyllene oxide (10.4%) and y-terpinene (9.2%).     

Composition and antioxidant activity of Senecio nudicaulis Wall. ex DC. (Asteraceae): a medicinal plant growing wild in Himachal Pradesh,India

The composition of essential oil isolated from Senecio nudicaulis Wall. ex DC. growing wild in Himachal Pradesh, India, was analysed, for the first time, by capillary gas chromatography (GC) and GC–mass spectrometry. A total of 30 components representing 95.3% of the total oil were identified. The essential oil was characterised by a high content of oxygenated sesquiterpenes (54.97%) with caryophyllene oxide (24.99%) as the major component. Other significant constituents were humulene epoxide-II (21.25%), α-humulene (18.75%), β-caryophyllene (9.67%), epi-α-cadinol (2.90%), epi-α-muurolol (2.03%), β-cedrene (1.76%), longiborneol (1.76%), 1-tridecene (1.16%) and citronellol (1.13%). The oil was screened for antioxidant activity using DPPH, ABTS and nitric oxide-scavenging assay. The oil was found to exhibit significant antioxidant activity by scavenging DPPH, ABTS and nitric oxide radicals with IC₅₀ values of 10.61 ± 0.14 μg mL^? 1, 11.85 ± 0.28 μg mL^? 1 and 11.29 ± 0.42 μg mL^? 1, respectively.     

Glass capillary gas chromatography with electron-capture detection. Separation of prostaglandins

Glass capillary gas chromatography of the prostaglandins was performed on a system including an all-glass, solventless injector; thermostable methylphenyl-polysiloxane glass capillary columns; and a conventional electron-capture detector fitted with a make-up gas tee. The principal stable metabolites of prostaglandin endoperoxide were separated as perfluorinated derivatives in 35 min. Detection limits equal or exceed those obtained for packed column separations and electron capture detection. Prostaglandin endoperoxide metabolic profiles from mammalian cell cultures were obtained using this system. These profiling studies are not possible with other chromatographic methods because of inferior resolution and sensitivity.     

千里光中几种黄酮和酚酸类成分的分离与鉴定

对千里光(Senecio scandens Buch.-Ham.)全草的乙酸乙酯提取部位进一步分离,得到4个黄酮类化合物和2个酚酸类化合物,经理化性质和NMR及MS谱学数据鉴定分别为槲皮素3-O-β-D-葡萄糖苷（Ⅰ）、金丝桃苷（Ⅱ）、槲皮素（Ⅴ）、异鼠李素（Ⅵ）、绿原酸（Ⅲ）和咖啡酸（Ⅳ）。 其中化合物Ⅰ~Ⅵ均为首次从千里光属植物中分离鉴定。     

Gas chromatography of fatty acids.

Lipids in foods contain a wide variety of fatty acids differing in chain length, degree of unsaturation, position and configuration of double bonds and the presence of special functional groups. Modern capillary gas chromatography offers excellent separation of fatty acids. Fused-silica capillary columns with stationary phases of medium polarity and non-polar methylsilicone stationary phases successfully separate most of the natural fatty acids. Special applications, such as the separation of complex cis-trans fatty acid mixtures and cyclic fatty acids, required particular chromatographic conditions, including the use of very long capillary columns or more polar stationary phases. The derivatization methods for the preparation of fatty acid esters also need to be optimized to obtain accurate quantitative results. This paper reviews the derivatization techniques, capillary columns and stationary phases commonly used in the gas chromatography of fatty acids in food.     

Gas chromatographic-mass spectrometric method for the determination of selenium in biological samples.

The determination of selenium by capillary gas chromatography-mass spectrometry (GC-MS), using an enriched stable isotope 76Se as internal standard, is described. Reference values for selenium in human biological fluids (serum, red blood cells and urine) are reported. With the advent of new compact capillary GC-MS (benchtop) instruments, this method will be very simple and accurate for routine analysis.     

6alpha-Angeloylplatynecine: a new alkaloid from Senecio nemorensis subsp. fuchsii (C.C. Gmelin) celak

The new alkaloid 6alpha-angeloylplatynecine, together with other four known pyrrolizidine alkaloids was identified from above ground parts of Senecio nemorensis subs. fuchsii.     

Capillary gas chromatography based on a capsule-insertion technique. 1. General aspects and comparison with split-injection systems

A capsule-insertion system tailored to the needs of capillary gas chromatography is described. It provides the basis for a truly quantitative and improved qualitative approach to open tubular capillary GLC. The advantages of the system lie in its simplicity of handling and in the possibility of using relatively low injection temperatures, thus reducing the risks to thermally unstable samples. The observed high efficiencies characterizing this capillary GLC capsule technique allow full advantage to be taken of the operating capacity of the superior capillary columns to give a performance competitive with the best known split-injection systems.     

Dynamic pH junction-sweeping capillary electrophoresis for online preconcentration of toxic pyrrolizidine alkaloids in Chinese herbal medicine

There is a need to develop simple yet effective preconcentration methods to enhance concentration sensitivity for CE analysis of trace level analytes in real samples, particularly when commonly available but less sensitive detection methods, e.g., UV detection, are used. In this report, a hyphenated online preconcentration strategy combining dynamic pH junction with sweeping (i.e., dynamic pH junction-sweeping) was employed for the analysis of four toxic pyrrolizidine alkaloids (PAs) of senkirkine, senecionine, retrorsine, and seneciphylline in Chinese herbal medicine (Kuan donghua). Direct electrokinetically focusing of a large sample volume injection (up to 20% of capillary length) on the capillary was performed using the dynamic pH junction-sweeping method. A sample matrix consisting of 10 mM phosphate with 20% methanol at pH 4.0 and a BGE containing 20 mM borate, 30 mM SDS, and 20% methanol at pH 9.1 were utilized to realize dynamic pH junction-sweeping for PAs. This online preconcentration strategy resulted in sensitivity enhancement factors ranging from 23.8- to 90.0-fold for the four toxic PAs, giving an LOD as low as 30 ppb for the PAs. Critical factors such as sample matrix type, pH, and salt concentration were also examined to achieve higher sensitivity enhancement, shorter analysis time, and better resolution. The results indicate that the proposed dynamic pH junction-sweeping technique is a powerful alternative approach for identification and determination of trace levels of these toxic PAs and other hydrophobic, protonatable compounds in real samples.     

Chromatographic separation of cholesterol in foods.

Based on the current literature and on experience gained in the laboratory, a simplified procedure using direct saponification (0.4 M potassium hydroxide in ethanol and heating at 60 degrees C for 1 h) is the most appropriate method for the determination of total cholesterol in foods. Extraction of the unsaponifiable matter with hexane is efficient and no extra clean-up is required before quantification. An internal standard, 5 alpha-cholestane or epicoprostanol, should be added to the sample prior to saponification and, together with reference standards, carried through the entire procedure to ensure accurate results. A significant improvement in cholesterol methodology has been achieved by decreasing the sample size and performing all the sample preparation steps in a single tube. The method has the advantages of elimination of an initial solvent extraction for total lipids and errors resulting from multiple extractions, transfers, filtration and wash steps after saponification. The resulting hexane extract, which contains a variety of sterols and fat soluble vitamins, requires an efficient capillary column for complete resolution of cholesterol from the other compounds present. The development of fused-silica capillary columns using cross-linked and bonded liquid phases has provided high thermal stability, inertness and separation efficiency and, together with automated cold on-column gas chromatographic injection systems, has resulted in reproducible cholesterol determinations in either underivatized or derivatized form. If free cholesterol and its esters need to be determined separately, they are initially extracted with other lipids with chloroform-methanol followed by their separation by column or thin-layer chromatography and subsequently analysed by gas or liquid chromatography. Although capillary gas chromatography offers superior efficiency in separation, the inherent benefits of liquid chromatography makes it a potential alternative. Isotope dilution mass spectrometry has been widely accepted as a reliable analytical method for highly accurate determination of cholesterol in serum and several definitive methods have been reported. The combination of capillary gas chromatography with mass spectrometry has become an excellent approach for the determination of cholesterol in complex mixtures of sterols and tocopherols, providing high resolution with positive identification. When used to determine cholesterol in multi-component foods, spectrophotometric methods have been documented to overestimate significantly the amount of cholesterol owing to the presence of other interfering substances. A re-evaluation of food products should be undertaken using the more specific chromatographic methods to accumulate data that will more accurately reflect the true cholesterol content.     

Interface for capillary electrophoresis coupled with inductively coupled plasma atomic emission spectrometry.

A modified concentric nebulizer was used as the interface to couple capillary electrophoresis (CE) to inductively coupled plasma atomic emission spectrometry (ICP-AES). The CE capillary replaces the central tube of the concentric nebulizer. The tip of the nebulizer tapers slowly to allow uncertainty in the position of the capillary. A platinum wire was inserted into the CE capillary to provide electrical connection to the CE power supply. pH changes inside the capillary due to electrolysis of the background buffer electrolyte was small and has minimal effects on the CE separation. The peak broadening effects due to the nebulizing gas flow, however, were significant. Resolution decreases quickly when the flow-rate of the carrier gas increases. Sample stacking technique was used to improve the resolution of species of opposite charge, e.g., Cr(VI) vs. Cr(III) ions. Detection limit of Cr based on peak area is approximately 10 ppb for the CE-ICP-AES system.     

Pattern recognition for analysis of cigarette smoke by capillary gas chromatography. Part 1: Total particulate matter (TPM)

Complex smoke profiles from fused silica capillary gas chromatography of different cigarette types produce rich information requiring computer and sophisticated statistical analysis to reveal the hidden correlation patterns. In our technique, a Cambridge pad containing total particulate matter (TPM) is extracted with Freon-11 in a micro-Soxhlet apparatus. The condenser is maintained at ?15°C. After extraction, Freon-11 is allowed to evaporate under mild conditions. Bis(trimethylsilyl)trifuoroacetamide (BSTFA) is subsequently added to the extract. Trimethylsilylation is completed by maintaining the reaction vessel at 60°C for two hours. A microprocessor-controlled capillary gas chromatograph with an automatic sampler is used to generate profiles. A link to a host computer provides for transmission of profile reports and access to various statistical and graphic packages. Factor and discriminant analyses are applied to gas chromatographic data from TPM extracts because of their ability in data reduction, pattern extraction and ranking the importance of the gas chromatographic peaks. Some preliminary results from these statistical analyses are discussed.     

Separation of C19 and C21 dihydroxysteroids by open-hole tubular glass columns and lipophilic gel chromatography.

The combination of lipophilic gel chromatography and high-resolution glass capillary chromatography has been shown to be an important means of identification and quantification of steroid urinary metabolites. Some problems in the use of capillary columns, such as coating with polar and apolar stationary phases, column performance, thermal stability and injection systems have been investigated and this type of chromatography has been used in the analysis of 33 dihydroxysteroids. Gel chromatography is a method complementary to high-efficiency gas chromatography. The steroids are eluted according to the number of hydroxyl groups in the molecules.     

Open tubular column supercritical fluid chromatography/mass spectrometry on a benchtop mass spectrometer

A benchtop SFC/MS system is described which utilizes supercritical carbon dioxide in a 50 micron diameter open tubular column interfaced directly to an unchanged commercially available benchtop capillary GC/MS system equipped with a chemical ionization (CI) source. A small amount of methane reagent gas was admitted co-axially to a capillary restrictor at the exit of the capillary chromatographic column. This make-up gas served as the CI reagent gas and appeared to optimize the sensitivity of the system while providing abundant (M+1) ions for the analytes investigated in this study. Good chromatographic intergrity was obtained for the GC/MS test compound, decafluorotriphenylphosphine (DFTPP), but the capillary restrictor appeared to cause some tailing of the ion current profiles resulting from low nanogram levels of caffeine and some fatty acid esters. Improvements in the SFC/MS capillary restrictor interface and the pumping system of the benchtop GC/MS system should increase the capability of this system for future applications.     

Two-dimensional capillary gas chromatography without intermediate trapping. Electron capture detector quantitation of an amino alcohol (KABI 2128) in serum after trifluoroacetylation

A two- dimensional gas chromatograph based on the Deans switching principle is described. The unit comprises two separate ovens, each containing a fused silica capillary column. The columns are joined in a specially designed manifold permitting heart cuts to be performed without significant decrease in efficiency. The switching speed and the retention time stability of the system made it possible to perform heart cuts of only a few seconds' duration. The system has been used under isothermal conditions for the determination of an amino alcohol (KABI 2128) in the low ng/ml range after trifluoroacetylation and with electron capture detection. A much shorter clean-up procedure could be used in combination with the two-dimensional gas chromatograph as compared to a method using a single glass capillary column.     

Two-Dimensional Gas Chromatography. Concepts,Instrumentation, and Applications – Part 1: Fundamentals,Conventional Two-Dimensional Gas Chromatography,Selected Applications

The writer of this review published in 1978 a three-part article on two-dimensional gas chromatography in the first three issues of this journal [1]. The review was written at a time when capillary column GC was still in its infancy. Commercial columns were (essentially) unavailable and sample introduction into capillary columns was done exclusively in the split mode. Two-dimensional separations were explored in only a few laboratories. The limitations of capillary column technology made this exercise rather difficult. The introduction of fused silica capillary columns in the early eighties drastically changed the landscape in which gas chromatography was practiced. It took the chromatographic community just a few years to convert from packed columns to capillary columns. Instrumentation and accessories specifically designed for capillary column use came onto the market. This writer had great hopes that the revolution in capillary column GC would be mirrored in the development of instrumentation for Two-Dimensional Gas Chromatography. This never materialized. On the contrary, tentative steps taken by a few manufacturers and suppliers of chromatographic equipment fizzled out. It was perhaps the introduction of relatively inexpensive and user friendly GC/MS instrumentation, in combination with nearly indestructible fused silica capillary columns that took away the incentive to develop commercially viable Two-Dimensional Gas Chromatography. Much of the thinking went like this: why insist on good chromatography if mass spectrometry can do the job without the need for complete separation. Some progress in the further development of conventional Two-Dimensional Gas Chromatography has certainly been made over the last 20 years but there has not been a great deal of excitement. Applications have also been relatively sparse and they are limited to just a few areas. Science does not remain static and chromatography is no exception. Progress in gas chromatography is driven by new technology and ideas. Substantial improvements in two-dimensional GC were not forthcoming until Phillips and his research group introduced and implemented an entirely new form of Two-Dimensional Gas Chromatography, called comprehensive two-dimensional GC, or GC×GC. This breakthrough occurred only in 1991 [2]. It does take some time before scientists change attitudes and habits. There is always a time lag between the introduction of new technology and its general acceptance. The public's attitude toward comprehensive Two-Dimensional Gas Chromatography is probably no exception. The number of scientists who are actively pursuing this new branch of gas chromatography is still very small. It is often a single individual who carries the torch. J.B. Phillips' name is synonymous with comprehensive Two-Dimensional Gas Chromatography. He is not only its inventor and proponent but his fertile mind has initiated research in other related areas. Sadly, he passed away shortly before this review was written. This contribution is dedicated to his memory.     

A novel nanoflow interface for atmospheric pressure ionization mass spectrometry

A novel spray-ionization technique for nanoflow liquid chromatography/mass spectrometry (nLC/MS) has been developed by modifying the sonic spray ionization (SSI) technique. A solution from a tapered fused-silica capillary is sprayed by a gas flow coaxial to the capillary, and ions produced are analyzed with an ion-trap mass spectrometer. The ion intensity is shown to have a steep threshold at a low gas velocity and to be much less dependent on the gas velocity than that of conventional SSI, in which the ion intensity is strongly dependent on the gas velocity and reaches its maximum at sonic velocity. Thus, we conclude that the concentration of charge in the solution at the tapered capillary tip with an inner diameter of 15 microm is almost at saturation so that charged droplets are produced from the solution by electrical force, rather than by sheer stress due to the gas flow. The ions are readily produced from these charged droplets. Preliminary results are compared with results obtained with a miniaturized electrospray unit.     

Alkaloids of Senecio Taiwanensis Hayata and Senecio Morrisonensis Hayata

Two alkaloids, rosmarinine (I) from Senecio taiwanensis Hayata and integerrimine(II) from Senecio morrisonensis Hayata, were isolated and identified respectively.