Liquid Chromatography of Isomeric Phenols and Aromatic Acids Using a Poly (Ethyleneimine) Coated Silica Gel Micro-Column

Abstract

Ortho-, meta- and para-isomers of various derivatives of phenols and aromatic acids have been separated on a cross-linked poly (ethyleneimine) coated silica gel micro-column liquid chromatography with very dilute carbonate or phosphate eluents.     

The effect of arsenicals on cell suspension cultures of the Madagascar periwinkle (Catharanthus roseus)

Catharanthus roseus cells were grown in the presence of arsenite, arsenate, methylarsonate and dimethylarsinate. Cell growth and arsenical uptake were monitored. Reduction of arsenate, methylation of arsenic and demethylation of methylarsenic species are described. Alkaloid production by the cells is dramatically influenced by the presence of arsenicals. ¹H NMR studies of methylarsonate uptake by whole cells of C. roseus are reported.     

薄层色谱溶剂系统的优化设计

采用复合形法,根据色谱优化函数对肾上腺皮质激素类、磺胺类药物及银杏粉针剂的薄层溶剂系统进行了最优化设计。肾上腺皮质激素类药物的最佳溶剂系统为１,２－二氯乙烷－苯－甲醇（４．８１４．４２０．７８）;磺胺类药物的最佳溶剂系统为甲苯－无水乙醇－二氯乙烷－氯仿（２．３０１．４６３．３２２．９２）;银杏粉针剂的最佳溶剂系统为氯仿－甲醇－乙酸乙酯（３．３０３．２９３．４１）,实验结果与计算结果一致。     

Carbon monoxide poisoning as a probe for the active site(s) of a nickel-based olefin oligomerization catalyst

The interaction of the olefin oligomerization catalyst system derived from [Ni(sacsac)(PBu₃)Cl] (sacsac = pentane-2,4-dithionate = dithioacetylacetonate) with carbon monoxide (CO) has been examined by a combination of ³¹P NMR and FTIR spectroscopy. The catalyst is rapidly and completely inhibited by CO; however, removal of the CO restores catalytic activity. A CO-adduct of the active catalyst has a characteristic CO stretching frequency of 2042 cm^?1, and δ³¹P 9.9 ppm. Carbon monoxide does not react with [Ni(sacsac)(PBu₃)Cl], but [Ni(sacsac)(PBu₃)(Cl)] reacts with any of Et₂AlCl, BuLi, Li[Et₃BH] or K[(s-Bu)₃BH] under an atmosphere of carbon monoxide in the presence or absence of olefin to produce [Ni(PBu₃)(CO)₃], which has been identified by FTIR and ³¹P NMR. [Ni(sacsac)(PBu₃)Cl] reacts completely with BuLi or K[(s-Bu)₃BH] to form catalytically inactive species which yield active catalysts on addition of Et₂AlCl.     

Characterization and purification of fatty acid methyl esters from the liver oil of the deep sea shark (Centrophorus squamosus) by gas chromatography-mass spectrometry and countercurrent chromatography

Summary In the course of our studies on the location of marine products, we have directed our attention to the saponifiable fraction of the liver oil from the deep sea shark (Centrophorus squamosus). Different analytical and preparative techniques, such as high-performance liquid chromatography (HPLC), countercurrent chromatography (CCC), and gas chromatography-mass spectrometry [GC-MS, electron impact (EI) and positive-ion chemical ionization (PCI)] were used. These methods allowed us to characterize, after various derivatizations, most of the fatty acids formed after the saponification of the oil, and to purify two of them, namely: docosahexaenoic acid (DHA or 226) and docosamonoenoic acid (DMA or 221).     

硅胶柱与凝胶柱净化/气相色谱-质谱联用测定植物叶片中多环芳烃

建立了索氏提取-硅胶柱和凝胶柱净化/气相色谱-质谱联用(GC-MS)测定植物叶片中多环芳烃的分析方法。叶片中的多环芳烃经二氯甲烷-正己烷(体积比1∶1)索氏提取,提取液采用硅胶柱和凝胶柱两步净化(手填硅胶柱和GPC柱)后,进行GC-MS测定,根据保留时间和特征离子进行定性,内标法定量。方法检出限为0.025 1~5.80 ng/g,加标回收率为82.2%~130%,相对标准偏差不大于11%。该方法能有效去除植物叶片中的色素与油脂,适用于植物叶片中多组分多环芳烃的痕量分析,为测定植物组织内多环芳烃的含量提供了技术支撑。     

Water-soluble poly(n-vinylamides)as a basis for the synthesis of polymeric carriers of biologically active compounds

The method for preparation of copolymers of N-vinylpyrrolidone (VP) and N-vinylamine (VA) with high yield were developed; the method involves radical copolymerization of VP with N-vinylformamide(VFA) followed by the removal of formyl protecting group in the presence of inorganic acids. The optimal conditions for synthesis of copolymers with predefined compositions and molecular masses were determined. The influence of temperature, concentrations of reactants, and the nature of an acid on the rate of formyl group removal was estimated. Spectral and chromatographic methods of analytical control of the contents of residual monomers and formic acid (which forms during acidic hydrolysis of the copolymer) were developed.     

Dual‐column capillary microextraction (CME) combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV‐ICP‐MS) for the speciation of arsenic in human hair extracts

In this work, dual‐column capillary microextraction (CME) system consisting of N‐(2‐aminoethyl)‐3‐aminopropyltrimethoxysilane (AAPTS)‐silica coated capillary (C1) and 3‐mercaptopropyl trimethoxysilane (MPTS)‐silica coated capillary (C2) was developed for sequential separation/preconcentration of arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)] in the extracts of human hair followed by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV‐ICP‐MS) detection with iridium as permanent modifier. Various experimental parameters affecting the dual‐column microextraction of different As species had been investigated in detail. It was found that at pH 9, As(V) and MMA could be quantitatively retained by C1 and only As(III) could be quantitatively retained by C2. With the aid of valve switching, As(V)/MMA(V) retained on C1 and As(III) retained on C2 could be sequentially desorbed by 10 µl of 0.01 mol l^?1 HNO₃ [for As(V)], 0.1 mol l^?1 HNO₃ [for MMA(V)] and 0.2 mol l^?1 HNO₃‐3% thiourea (m/v) [for As(III)], respectively, the eluents were immediately introduced into the Ir‐coated graphite tubes for further ETV‐ICP‐MS detection. With two‐step ETV pyrolysis program, Cl^? in the sample matrix could be in situ removed, and the total As in the human hair extracts or digested solution could be interference‐free, determined by ETV‐ICP‐MS. DMA(V) in the human hair extracts was obtained by subtraction of total As in the human hair extracts from other three As species. Under the optimized conditions, the detection limits (3 σ) of the method were 3.9 pg ml^?1 for As(III), 2.7 pg ml^?1 for As(V), 2.6 pg ml^?1 for MMA(V) and 124 pg ml^?1 for total As with the relative standard deviations less than 7.0% (C = 0.1 ng ml^?1, n = 7), and the enrichment factor was 286, 262 and 260 for As(III), As(V) and MMA(V), respectively. The developed method was successfully applied for the speciation of arsenic in the extracts of human hair. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of arsenic species in seafood samples from the Aegean Sea by liquid chromatography-(photo-oxidation)-hydride generation-atomic fluorescence spectrometry

In this study arsenic compounds were determined in mussels (Mytulis galloprovincialis), anchovies (Engraulis encrasicholus), sea-breams (Sparus aurata), sea bass (Dicentrarchus labrax) and sardines (Sardina pilchardus) collected from Aegean Sea using liquid chromatography-photo-oxidation-hydride generation-atomic fluorescence spectrometry [LC-(PO)-HG-AFS] system. Twelve arsenicals were separated and determined on the basis of their difference in two properties: (i) the pK_a values and (ii) hydride generation capacity. The separation was carried out both with an anion- and a cation-exchange column, with and without photo-oxidation. In all the samples arsenobetaine, AB was detected as the major compound (concentrations ranging between 2.7 and 23.1 μg g⁻¹ dry weight), with trace amounts of arsenite, As(III), dimethylarsinic acid, DMA and arsenocholine, AC, also present. Arsenosugars were detected only in the mussel samples (in concentrations of 0.9-3.6 μg g⁻¹ dry weight), along with the presence of an unknown compound, which, based on its retention time on the anion-exchange column Hamilton PRP-X100 and a recent communication [E. Schmeisser, R. Raml, K.A. Francesconi, D. Kuehnelt, A. Lindberg, Cs. Soeroes, W. Goessler, Chem. Commun. 16 (2004) 1824], is supposed to be a thio-arsenic analogue.     

Separation and sensitive determination of arsenic species (As/As) using the yeast-immobilized column and hydride generation in ICP–AES

Inorganic arsenic was separated using the yeast-immobilized column. Saccharomyces cerevisiae was covalently bonded unto the controlled pore glass, which showed selective preconcentration of As⁵⁺ over As³⁺. The effluent was directly connected to hydride generation (HG) to increase sensitivity. The optimum pH condition for the retainment of arsenic at the column was 7. As⁵⁺ and As³⁺ were completely separated in a few minutes with the flow rate of 1.5 ml min⁻¹. Three molars of nitric acid was adequate both for the elution of As⁵⁺ and hydride generation. The accuracy of the technique was tested with NIST SRMs. Quantitative analysis of arsenic species for herbicide, pesticide, and cigarette were performed, and the results showed good agreements with the suggested values. Yeast-immobilized column-HG-ICP showed a promising future for the arsenic speciation study.     

The F NMR spectrum of bis-trifluoromethylmercury Hg(CF3)2 in the nematic phase: DAISY — a novel program system for the analysis and simulation of NMR spectra

The ¹⁹F NMR spectrum of bis-trifluoromethylmercury in the nematic phase has been analysed using the DAISY program system. The scalar and the dipolar coupling constants have been obtained.     

Quantification and determination of enantiomeric ratios of chiral PCB 95, PCB 132, and PCB 149 in shark liver samples (C. coelolepis) from the Atlantic Ocean

Chiral 2,2′,3,5′,6-pentachlorobiphenyl (PCB 95), 2,2′,3,3′,4,6′-hexachlorobiphnyl (PCB 132) and 2,2′,3,4′,5′,6-hexachlorobiphenyl (PCB 149) were quantified in Atlantic Ocean shark liver samples (C. coelolepis) by gas chromatography-mass spectrometry (GC-MS) and their enantiomeric ratios were studied by multidimensional gas chromatography (MDGC) with an achiral-chiral column combination and detected by ECD and MS/SIM. The concentration range of the chiral PCBs was from 2 to 6 ng/g (fresh weight), which represents 2–6 % of the total PCB mean concentration. The investigations revealed a small enantiomeric bias of PCB 132 in most of the samples studied (ER = 0.75–0.89, ee = 6–14%), while PCB 95 and PCB 149 were present in racemic or almost racemic form.     

The use of optical emission spectrometry with microwave induced plasma (MIP) discharges in a surfatron combined to different types of hydride generation for the determination of arsenic

The stability and analytical figures of merit of argon microwave induced plasma (MIP) discharges in a surfatron as sources for optical emission spectrometry (OES) are described. These MIPs have been used for the determination of arsenic after hydride generation. They could cope with the excess of hydrogen developed during the hydride generation step and thus not necessitated an isolation of the hydrides before releasing them into the MIP. Two methods for the generation of the volatile AsH₃ were applied. First a micro method was used with solid NaBH₄ on which 10 1 of the acidified sample solution is transferred. Its capabilities were compared to those of continuous hydride generation using a 5% (w/w) NaBH₄-solution and continuous liquid removal in a flow cell. Both methods were optimized for an argon MIP operated at a power of 120–160 W and gas flows of 20 l/h Ar. In the case of solid NaBH₄ the detection limit for As has been found to be 1.0 g/ml (10 ng) and with the flow cell hydride generation 50 ng/ml. The calibration curves are linear over three orders of magnitude. Interferences caused by Sb, Fe, Sn and NaCl were investigated. No interferences occurred for Sb up to an interferent concentration of 250 g/ml. The presence of Fe causes a significant depression of the As signal whereas an increase of the As signal was observed in the case of Sn. High NaCl concentrations did not influence the As signals when using continuous hydride generation, but had a great influence when using solid NaBH₄.     

The photodynamics of the [Ru(bpy)<Subscript>3</Subscript>]<Superscript>2+</Superscript> ion dopant in a solvent exposed silica sol–gel thin film

The [Ru(bpy)₃]²⁺ ion was encapsulated in a silica based sol–gel thin film, and the luminescence decay time constant of the photo-excited ³MLCT (metal-ligand-charge-transfer) was examined when this thin film was immersed in water, methanol, ethanol, 2-propanol, and glycerol. The luminescence decays of the films in the methanol, 2-propanol, and glycerol were better explained by a KWW model, while the luminescence decay of film immersed in water and ethanol were both well explained by a single exponential decay. Intriguingly, the dynamics of the dopants immersed in water, ethanol as well as in sol–gel bulk deviated from a single exponential fit and began to better explained by the the KWW model as temperature increased. The energy gap, ΔE(sol–gel film) and ΔE(solution), between the lowest ³MLCT state and atom localized ³ dd state for dopants under the presence of all solvents tested in this study were extracted from the temperature dependence study of the luminescence decay time constant. Generally, the ΔE(sol–gel film) values of ethanol and water were reduced from ΔE(solution), and ΔE(sol–gel film) value in all solvents matched the value of ΔE for sol–gel bulk. The effect on the dynamics in solvent over three weeks was investigated, and the films immersed in water presented the most remarkable monotonic increase in relaxation rates finally approaching the asymptotic value observed in the water solution. This phenomenon was considered to correspond to a trapping environment change due to a hydrophilic interaction through sequential intrusion of water or ethanol solvent into sol–gel pores.     

Strongly segregated cubic microdomain morphology consistent with the double gyroid phase in high molecular weight diblock copolymers of polystyrene and poly(dimethylsiloxane)

We report the observation of a cubic phase consistent with the double gyroid structure in strongly segregated diblock copolymers of PS‐b‐PDMS over a volume fraction (φ_PDMS) range of ～0.39 to 0.45. The samples have respective molecular weights of 127 kg/mol and 73 kg/mol and degree of segregation Nχ equal to 187 and 106, respectively, at annealing temperature of 130 °C. It is important to highlight that two out of the total four samples investigated, exhibited hexagonally close packed cylindrical domains of PDMS and alternating lamellae at φ_PDMS = 0.39 and 0.45, respectively, indicating the possible narrow range of the DG morphology for the specific diblock copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2419–2427, 2009     

Conventional radical polymerization and iodine‐transfer polymerization of 4′‐nonafluorobutyl styrene: Surface and thermal characterizations of the resulting poly(fluorostyrene)s

4′‐Nonafluorobutylstyrene (3) was synthesized and polymerized by conventional and controlled radical polymerization (iodine transfer polymerization (ITP)). Such an aromatic fluoromonomer was prepared from Ullmann coupling between 1‐iodoperfluorobutane and 4‐bromoacetophenone followed by a reduction and a dehydration in 50% overall yield. Two radical polymerizations of (3) were initiated by AIBN either under conventional or controlled conditions, with 1‐iodoperfluorohexane in 84% monomer conversion and in 50% yield. ITP of (3) featured a fast monomer conversion and a linear evolution of the ln([M]₀/[M]) versus time. The kinetics of radical homopolymerization of (3) enabled one to assess its square of the propagation rate to the termination rate (k_p²/k_t) in ITP conditions (36.2·10^?2 l·mol^?2·sec^?2 at 80 °C) from the Tobolsky's kinetic law. Polydispersity index (?) of the fluoropolymer achieved by conventional polymerization was 1.30 while it worthed 1.15 when synthesized by ITP. Thermal stabilities of these oligomers were satisfactory (10% weight loss under air occurred from 305 °C) whereas the melting point was 47 °C. Contact angles and surface energies assessed from spin‐coated poly(3) films obtained by conventional (hysteresis = 18°, surface energy 18 mN.m^?1) and ITP (hysteresis = 47°, surface energy 15 mN.m^?1) evidenced ? values' influence onto surface properties of the synthesized polymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3202–3212     

Reaction of Os3(μ-Cl)2(CO)10 with Ph2PCH2PPh2. The formation of a novel 12-membered macrocycle containing C, P, Cl, and Os atoms in the ring

The reaction of Os₃(μ-Cl)₂(CO)₁₀ (1) with Ph₂PCH₂PPh₂ (dppm) in a toluene solution at 65°C results in novel osmium complexes [Os₃(μ-Cl)₂(CO)₉]₂(dppm) (2) and [Os₃(μ-Cl)₂(CO)₈]₂(dppm)₂ (3). Compounds 2 and 3 were characterized by¹H and³¹P NMR, and IR spectroscopy and their structures were established by X-ray analysis. In both compounds, dppm is a bridging ligand between the two cluster units. Molecule3 can be considered as an unusual 12-membered macrocycle containing C, P, Cl, and Os atoms in the ring. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1844–1851, September, 1998.