Supercritical fluid extraction of oxindole alkaloids from Uncaria tormentosa

Supercritical fluid extraction of oxindole alkaloids from Uncaria Tormentosa is described. The extraction was performed with supercritical carbon dioxide alone and with supercritical carbon dioxide modified with 10% metanol, and the extracts were analyzed by GC/MS and HPLC/MS.     

Capillary supercritical fluid chromatography of limonoids

Capillary supercritical fluid chromatography (SFC) with carbon dioxide as the mobile phase has been used to separate a mixture of limonoid standards. Chromatographic conditions were optimized to enable analysis of plant extracts. The seed of Aphanamixis polystacha (Meliaceae) and the stem bark of Harpephyllum caffrum (Anacardiaceae) were extracted with hexane and the extracts were analyzed by SFC to demonstrate the potential of the technique as a screening tool. SFC analysis indicated the presence of limonoids in the hexane extract of the bark of Entandrophragma delevoyii (Meliaceae). One limonoid and two protolimonoids isolated from the extract were separated by SFC.     

Supercritical extraction of thyme (Thymus vulgaris L.)

Summary Chromatographic methods for the qualitative and quantitative analysis of thyme (Thymus vulgaris L.) extracts (essential oil obtained by steam distillation and extracts obtained by carbon dioxide supercritical fluid extraction and methylene chloride) are described. The composition of extracts obtained at different pressures (from 80 bar to 400 bar) and constant temperature (40°C) is discussed. The extraction system thyme— supercritical carbon dioxide was modelled by empirical equations defining the dependence of the total extract (TE) solubility and thymol solubility in CO₂ on the density of carbon dioxide.     

Use of Electrogenerated Bromine for Estimating the Total Antioxidant Capacity of Plant Raw Materials and Plant-based Medicinal Preparations

Based on the results of determining individual antioxidants,electrogenerated bromine was proposed as a regent for the coulometric determination of the antioxidant capacity of aqueous and aqueous–alcoholic extracts of 35 phytopreparations.     

Isolation of bioactive preparations from alcoholic extracts ofChlorella vulgaris

Summary Three groups of bioactive substances (provitamins of the A group, vitamins of the F group, and sodium chlorophyllin) have been isolated from alcoholic extracts of the micro algaChlorella vulgaris. The conditions of separating these substances are given. The qualitative and quantitative compositions of the groups isolated have been investigated by paper chromatography, gas-liquid chromatography, and spectral analysis.Siberian Technological Institute, Krasnoyarsk. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 213–216, March–April, 1979.     

Supercritical fluid extraction of kava lactones from Piper methysticum (kava) herb

Supercritical fluid extraction of kava lactones from Piper methysticum Forst. herb is described here. The extraction was performed with supercritical carbon dioxide alone and supercritical carbon dioxide modified with 15% ethanol, and the extracts were analyzed by gas chromatography/mass spectrometry. Seven lactones including: 7,8-dihydrokavain; kavain; 5,6-dehydrokavain; 5, 6, 7, 8-tetrahydroyangonin; dihydromethysticin; yangonin; and methysticin were the major constituents in the SFE extract.     

Determination of a flame retardant hydrolysis product in human urine by SPE and LC–MS. Comparison of molecularly imprinted solid-phase extraction with a mixed-mode anion exchanger

Diphenyl phosphate is a hydrolysis product and possible metabolite of the flame retardant and plasticiser additive triphenyl phosphate. A molecularly imprinted polymer solid-phase extraction (MISPE) method for extracting diphenyl phosphate from aqueous solutions has been developed and compared with SPE using a commercially available mixed-mode anion exchanger. The imprinted polymer was prepared using 2-vinylpyridine (2-Vpy) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, and a structural analogue of the analyte as the template molecule. The imprinted polymer was evaluated for use as a SPE sorbent, in tests with both aqueous standards and spiked urine samples, by comparing recovery and breakthrough data obtained using the imprinted form of the polymer and a non-imprinted form (NIP). Extraction from aqueous solutions resulted in more than 80% recovery. Adsorption by the molecularly imprinted polymer (MIP) was non-selective , but selectivity was achieved by selective desorption in the wash steps. Diphenyl phosphate could also be selectively extracted from urine samples, although the urine matrix reduced the capacity of the MISPE cartridges. Recoveries from urine extraction were higher than 70%. It was important to control pH during sample loading. The MISPE method was found to yield a less complex LC–ESI–MS chromatogram of the urine extracts compared with the mixed-mode anion-exchanger method. An LC–ESI–MS method using a Hypercarb LC column with a graphitised carbon stationary phase was also evaluated for organophosphate diesters. LC–ESI–MS using negative-ion detection in selected ion monitoring (SIM) mode was shown to be linear for diphenyl phosphate in the range 0.08–20 ng L^–1.     

Adsorption of Carbon Dioxide on Chemically Modified High Surface Area Carbon-Based Adsorbents at High Temperature

The adsorption capacity of carbon dioxide on high surface area carbon-based adsorbents before and after chemical modification at 28°C and 300°C have been studied. The high adsorption capacity adsorbents for carbon dioxide at high temperature have been developed by introducing MgO and S–CaO–MgO on carbon-based adsorbents. Their adsorption capacities for carbon dioxide were 0.28 and 0.22 m mol/g at 300°C, 1 Bar, respectively.     

Analytical Method Development for the Simultaneous Determination of Five Human Pharmaceuticals in Water and Wastewater Samples by Gas Chromatography-Mass Spectrometry

Summary Effective analytical methods for the simultaneous determination of five pharmaceuticals from various therapeutic classes in a variety of aqueous samples have been developed and method performance data are presented. The method involves the simultaneous extraction of the selected pharmaceuticals from the aqueous phase by solid phase extraction using a hyper cross linked, polystyrene-divinylbenzene polymer based sorbent. Analytes were eluted with methanol, derivatised with N-methyl-N-trimethylsilyltrifloroacetamide and analysed by gas chromatography – electron ionisation mass spectrometry (GC-EI-MS). Recoveries of 50 to 98% were established for waters spiked with the studied compounds at the low ng L^–1 level with the highest detection sensitivities being achieved in the selected ion monitoring (SIM) mode and the quantification limit of the procedure for sample sizes of 1000 ml was approximately 5 ng L^–1 for all matrices except sewage which was only tested to 20 ng L^–1. Analysis of domestic sewage from a large treatment works demonstrate the presence of all five compounds in both influents and effluents.     

Effects of different extraction methods and conditions on the phenolic composition of mate tea extracts

A simple and rapid HPLC method for determination of chlorogenic acid (5-O-caffeoylquinic acid) in mate tea extracts was developed and validated. The chromatography used isocratic elution with a mobile phase of aqueous 1.5% acetic acid-methanol (85:15, v/v). The flow rate was 0.8 mL/min and detection by UV at 325 nm. The method showed good selectivity, accuracy, repeatability and robustness, with detection limit of 0.26 mg/L and recovery of 97.76%. The developed method was applied for the determination of chlorogenic acid in mate tea extracts obtained by ethanol extraction and liquid carbon dioxide extraction with ethanol as co-solvent. Different ethanol concentrations were used (40, 50 and 60%, v/v) and liquid CO? extraction was performed at different pressures (50 and 100 bar) and constant temperature (27 ± 1 °C). Significant influence of extraction methods, conditions and solvent polarity on chlorogenic acid content, antioxidant activity and total phenolic and flavonoid content of mate tea extracts was established. The most efficient extraction solvent was liquid CO? with aqueous ethanol (40%) as co-solvent using an extraction pressure of 100 bar.     

Antioxidant, antimicrobial properties and phenolics of different solvent extracts from bark, leaves and seeds of Pongamia pinnata (L.) Pierre

This study appraises the antioxidant and antimicrobial attributes of various solvent extracts (absolute methanol, aqueous methanol, absolute ethanol, aqueous ethanol, absolute acetone, aqueous acetone, and deionized water) from bark, leaves and seeds of Pongamia pinnata (L.) Pierre. Maximum extraction yield of antioxidant components from bark (16.31%), leaves (11.42%) and seeds (21.51%) of P. pinnata was obtained using aqueous methanol (20:80). Of the extracts tested, the bark extract, obtained with aqueous methanol, exhibited greater levels of total phenolics [6.94 g GAE/100 g dry weight (DW)], total flavonoids (3.44 g CE/100 g DW), inhibition of linoleic acid peroxidation (69.23%) and DPPH radical scavenging activity (IC(50) value, 3.21 μg/mL), followed by leaves and seeds extracts. Bark extract tested against a set of bacterial and fungal strains also revealed the strongest antimicrobial activity with the largest inhibition zone and lowest minimum inhibitory concentration (MIC). HPLC analysis of aqueous methanol extracts from bark, leaves and seeds indicated the presence of protocatechuic, ellagic, ferulic, gallic, gentisic, 4-hydroxybenzoic and 4-hydroxycinnamic acids in bark (1.50-6.70 mg/100 g DW); sorbic, ferulic, gallic, salicylic and p-coumaric acids in leaves (1.18-4.71 mg/100 g DW); vanillic, gallic and tannic acids in seeds (0.52-0.65 mg/100 g DW) as the main phenolic acids. The present investigation concludes that the tested parts of P. pinnata, in particular the bark, have strong potential for the isolation of antioxidant and antimicrobial agents for functional food and pharmaceutical uses.     

Composition of the resinous substances of conifer needles. III. Waxy substances from the woody verdure ofPinus sylvestris

The individual compositions of the wax isolated from an isopropyl extract of the woody verdure and of an industrial sample of needle wax have been investigated with the aid of GLC. The acids isolated from the wax have been identified, and the alcoholic fraction has been separated without identification. It has been shown that the wax obtained from the isopropyl alcohol extracts is suitable for industrial use.Siberian Technological Institute, Krasnoyarsk. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 264–266, March–April, 1985.     

Characterization of Bioactive Compounds from Patchouli Extracted via Supercritical Carbon Dioxide (SC-CO2) Extraction

Patchouli extracts and oils extracted from Pogostemon cablin are essential raw material for the perfume and cosmetics industries, in addition to being used as a natural additive for food flavoring. Steam distillation is a standard method used for plant extraction. However, this method causes thermal degradation of some essential components of the oil. In this study, patchouli was extracted with supercritical carbon dioxide (SC-CO₂) under different conditions of pressure (10–30 MPa) and temperature (40–80 °C). The chemical components of the crude extracted oil and the functional group were characterized using gas chromatography-mass spectrometry (GC-MS) and Fourier Transform Infrared Spectroscopy (FT-IR). The extraction with supercritical carbon dioxide was shown to provide a higher yield (12.41%) at a pressure of 20 MPa and a temperature of 80 °C. Patchouli alcohol, Azulene, δ-Guaiene, and Seychellene are the main bioactive compounds that GC-MS results have identified. FTIR spectra showed alcohol, aldehyde, and aromatic ring bond stretching peaks. Extraction of patchouli with supercritical carbon dioxide provided a higher yield and a better quality of the crude patchouli oil.     

Method of obtaining allapinine from the epigeal part of Aconitum leucostomum

The industrial processes for obtaining allapinine (lappaconitine hydrobromide) from the epigeal part ofAconitum leucostomum have been studied. As a result, a rational method of obtaining allapinine from the plant raw material has been developed which consists in the extraction of the raw material with 80% ethanol and concentration to an aqueous residue, followed by extraction with chloroform, purification, the production of technical allapinine, and its recrystallization from methanol or from aqueous ethanol. The yield of allapinine satisfying the requirements of VFS 31-1667-86 amounts to 72–80% of its amount in the raw material.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 91–94, January–February, 1988.     

Dissolution and extraction of actinide oxides in supercritical carbon dioxide containing the complex of tri-n-butylphosphate with nitric acid

Dissolution of individual actinide oxides (Th, U, Pu, Np), or their mechanical mixtures, as well as of solid solutions U–Pu, U–Np, U–Am and U-Pu-Eu oxides in supercritical fluid carbon dioxide (SF-CO₂) containing the complex of tri-n-butyl phosphate (TBP) with nitric acid (TBP–HNO₃) has been investigated. The effect of the calcination temperature of solid solutions of dioxides on the separation of actinides during supercritical fluid extraction (SFE) has been studied as well. It was shown for the first time that milligram amounts of uranium dioxide could be quantitatively dissolved in (SF-CO₂) containing the TBP–HNO₃ complex and efficiently separated from Pu, Np, and Th during SFE of mechanical mixture of these oxides. On the contrary, both U and Pu are quantitatively dissolved in SF-CO₂–TBP–HNO₃ during SFE from solid solutions of U–Pu dioxide. An increase of the calcination temperature of the mixed U(IV)–Pu(IV) dioxide from 850 to 1200 °C has no influence on the relative extraction yield of these actinides during SFE. To cite this article: T. Trofimov et al., C. R. Chimie 7 (2004).

Résumé

Dissolution d’oxides d'actinides et extraction d’éléments dans le dioxide de carbone supercritique contenant le complexe tri-n-butylphosphate–acide nitrique. La dissolution d’oxydes de Th, U, Pu et Np, de leurs mélanges et de solutions solides U–Pu, U–Np, U–Am et U–Pu–Eu dans le dioxyde de carbone supercritique (CO₂-SC) contenant le complexe tri-n-butyl phosphate–acide nitrique (TBP–HNO₃) a été étudiée, et notamment l’effet de la température de calcination des solutions solides. On montre que quelques milligrammes de UO₂ peuvent être dissous dans le système CO₂-SC–TBP–HNO₃ et être séparés de Pu, Np et Th en traitant un mélange d’oxydes. En revanche, U et Pu sont dissous dans la phase CO₂-SC–TBP–HNO₃ durant le traitement des solutions solides U(IV)–Pu(IV). Une augmentation de la température de calcination de 850 à 1200 °C de ces solutions solides n’a pas d’effet sur le rendement d’extraction des actinides. Pour citer cet article : T. Trofimov et al., C. R. Chimie 7 (2004).     

Pressurized Solvent Extraction of Paulownia Bark Phenolics

Paulownia bark is mostly utilized jointly with wood, but the possibility of a separate valorization through the pressurized extraction of bark bioactives has been assessed. Subcritical water extraction and supercritical CO₂ extraction are green technologies allowing shorter times than conventional solvent extraction under atmospheric shaken conditions. Subcritical water extraction was carried out at temperatures ranging from 140 to 240 °C and supercritical CO₂ extraction was performed at different pressures (10, 20 and 30 MPa), temperatures (35, 45 and 55 °C) and ethanol concentrations (0, 10 and 15% (w/w)). Subcritical water extraction under a non-isothermal operation during heating up to 160 °C (19 min) provided extraction yields up to 30%, and the extracts contained up to 7% total phenolics with an ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging capacity equivalent to 35% the activity of Trolox, whereas at 240 °C, the yield decreased to 20%, but the phenolic content reached 21%, and the antiradical activity was equivalent to 85% of Trolox. Supercritical CO₂ extraction at 30 MPa, 45 °C and 30 min reached a global yield of 2% after 180 min of extraction, but the product showed very low antiradical capacity. Gallic acid, vanillic acid, vanillin and apigenin were the major phenolic compounds found in the extracts.     

Characterization of nucleobases in sea buckthorn leaves: An HPTLC approach

The present study aims to establish a high-performance thin layer chromatography (HPTLC)-based comparative analysis, directed toward characterization of nucleobases in aqueous and alcoholic extracts of sea buckthorn leaves from three different varieties: Hippophae salicifolia, Hippophae rhamnoides mongolica, and Hippophae rhamnoides turkestanica. The alcoholic and aqueous leaf extracts from these sea buckthorn varieties were prepared using accelerated solvent extraction technique. A novel HPTLC method for separating and identifying six nucleobases, namely, guanosine, guanine, cytosine, adenine, uracil, and thymine were adopted. HPTLC analysis indicated the presence of one or more of these nucleobases in a total of six leaf extracts evaluated, their quantities varying from 0.23 to 7.76?µg nucleobase per mg of extract. Though a typical trend could not be observed in the values obtained, the extracts were found to be considerably rich with respect to nucleobase contents. The results acquired from HPTLC were subsequently validated by hyphenation with mass spectrometry and also by applying chemometric tools in form of heat maps, hierarchical cluster dendrograms, and principal component analysis. The presence of nucleobases in the leaf extracts was confirmed by HPLC as well but HPTLC proved to be a better approach for characterization of nucleobases in plant extracts, than high performance liquid chromatography (HPLC).     

Gas chromatography of epinephrine and norepinephrine after derivatization with chloroformates in aqueous media

Optimal conditions for the reaction of alkyl chloroformates with epinephrine and norepinephrine in aqueous solution have been evaluated. The maximal yield with 0.06 M methyl chloroformate was in the pH range 7.0–8.5. The derivatives formed are isolated by extraction with methylene chloride and gas chromatographed on 3% QF-1 with a nitrogen-selective detector after trimethylsilylation of the alcohol group.     

Electrosynthesis of N-tert-Butyl-2-benzothiazolesulfenamide

Conditions for the production of N-tert-butyl-2-benzothiazolesulfenamide (TBBS) in an oxidative condensation of 2-mercaptobenzothiazole and tert-butylamine are determined. The electrosynthesis occurs during electrolysis of a 4.5–5.0 M NaCl solution containing a water-immiscible organic solvent extracting TBBS. The process efficiency is the highest at the following conditions: a 1 : 8 ratio between 2-mercaptobenzothiazole and tert-butylamine, a DSA, a stainless-steel cathode, a current density of 300 A m^–2, and a continuous extraction of TBBS into a 3 : 1 mixture of carbon tetrachloride and acetonitrile. Under these conditions, the TBBS yield is 98–100%, the current efficiency is 74%, the process productivity is 0.9 kg m^–2 h^–1, and the electricity consumption is 1.9 kW h kg^–1. Repeated use of the aqueous phase corrected for the source products jeopardizes neither the process characteristics nor the product quality.     

Photoelectron spectral study of the thermolysis of benzofuroxan

Photoelectron spectroscopy data have shown that thermolysis of benzofuroxan vaporin vacuo results in thermal abstraction of the exocyclic oxygen to afford a nonvolatile product, which decomposes to give nitrogen monoxide, carbon monoxide, and carbon dioxide.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2238–2240, December, 1994.