Development and Validation of an Accurate LC Method for the Quantitative Determination of Voriconazole in a New Emulsion Formulation

A simple, sensitive and accurate liquid chromatographic method with UV detection was developed and validated to determine voriconazole in a new emulsion formulation. Chromatographic separation was achieved on a Diamonsil C₁₈ column (250 × 4.6 mm I.D., 5 μm) using a mobile phase consisting of acetonitrile-water-acetic acid (40:60:0.25, v/v/v) at a flow rate of 1.0 mL min^?1. The UV detection wavelength was set at 256 nm. The linear calibration curves were obtained in the concentration range of 1.00–100 μg mL^?1 with the limit of quantification of 1.00 μg mL^?1. The within- and between-run precisions in terms of percentage relative standard deviation were lower than 7.4 and 7.1%, respectively. The accuracy in terms of percentage relative error ranged from ?1.5 to 1.4%. This validated method was successfully applied to the determination of the content of voriconazole in a new emulsion formulation.     

Quantitative Determination of Microcystins in Rat Plasma by LC–ESI Tandem MS

A rapid and sensitive method was developed and validated for the determination of MCYST (microcystin)-RR, -LR, and [Dha⁷] MCYST-LR in rat plasma by liquid chromatography-tandem mass spectrometry. The analytes were extracted from rat plasma by protein precipitation, followed by solid-phase extraction. Liquid chromatography with electrospray ionization mass spectrometry, operating in selected reaction monitoring (SRM) mode, was used to quantify MCYST-RR, -LR, and [Dha⁷] MCYST-LR in rat plasma. The recoveries for each analyte in rat plasma ranged from 70.8 to 88.7%. The calibration curve was linear within the range from 0.005 to 1.25 μg mL^?1. The limit of detection were 1.4, 1.0, 0.6 ng mL^?1 for MCYST-RR, -LR, and [Dha⁷] MCYST-LR. The overall precision was determined on three different days. The values for within- and between-day precision in rat plasma were within 15%. This method was applied to the identification and quantification of microcystins in rat plasma with acute exposure of microcystins via intravenous injection.     

A Method for Quantifying Azoxystrobin Residues in Grapes and Soil Using GC with Electron Capture Detection

A relatively simple method for the determination of azoxystrobin residues in grapes and soil using gas chromatography equipped with electron capture detector (GC-ECD) is described. Samples were extracted with acetone, and further partitioned with dichloromethane and petroleum ether. The extracts were then cleaned up in a glass clean-up column filled with active charcoal and silica gel, and eluted with dichloromethane/ethyl acetate (70:30, v/v). The eluate was collected and concentrated for GC-ECD analysis. The results showed good linearity (r ² = 0.9998) over the concentration range of 6.25–400 ng mL^?1. The limits of detection (LOD) and quantification (LOQ) of azoxystrobin were 3 and 10 ng mL^?1. Recovery from soil and grape samples was in the range of 83.52–107.36 and 82.21–107.31%, with corresponding relative standard deviations (RSD) of 5.21–9.11 and 4.53–5.90% for the three fortified levels. Inter- and intra-day RSDs were in the range of 0.87–6.76 and 2.01–5.46%. The accuracy and sensitivity of the GC-ECD method was independently confirmed by LC and GC-MS. It was demonstrated that the proposed method was simple and efficient, and particularly suitable for detecting azoxystrobin residues in grapes and soil.     

Comparison of Anion-Exchange and Hydrophobic Interactions between Two New Silica-Based Long-Chain Alkylimidazolium Stationary Phases for LC

Two new silica-based long-chain alkylimidazolium stationary phases were prepared and characterized for their use in high-performance liquid chromatography. The stationary phases were both prepared by the reaction of chloropropyl silica with long-chain alkylimidazoles and were used to separate common inorganic anions. Hydrophobic interactions were also studied by the comparison of differential retention of various organic compounds. The alkyl chain length did not show an impact on the anion-exchange process but affected the hydrophobic interaction of the stationary phases.     

Two New Spirostanol Saponins from Reineckia carnea

Two new spirostanol saponins, (1β,3β,5β,25S)‐spirostan‐1,3‐diol 1‐(β‐D ‐xylopyranoside) ( 1 ) and (1β,3β,5β,25S)‐spirostan‐1,3‐diol 1‐[α‐L ‐rhamnopyranosyl‐(1→2)‐β‐D ‐fucopyranoside] ( 2 ), along with two known compounds, (1β,3β,5β,25S)‐spirostan‐1,3‐diol 1‐[α‐L ‐rhamnopyranosyl‐(1→2)‐β‐D ‐xylopyranoside] ( 3 ) and (1β,3β,4β,5β,25S)‐spirostan‐1,3,4,5‐tetrol 5‐(β‐D ‐glucopyranoside) ( 4 ) were isolated from the whole plant of Reineckia carnea. The structures of the new steroids were determined by detailed analysis of their 1D‐ and 2D‐NMR spectra and chemical methods, and by comparison with spectral data of known compounds. Compounds 3 and 4 were isolated from the genus Reineckia for the first time.     

Nature of catalytic activities of CoO nanocrystals in thermal decomposition of ammonium perchlorate

This work addresses the chemical nature of the catalytic activity of X-ray "pure" CoO nanocrystals. All samples were prepared by a solvothermal reaction route. X-ray diffraction indicates the formation of CoO in a cubic rock-salt structure, while infrared spectra and magnetic measurements demonstrate the coexistence of CoO and Co 3O 4. Therefore, X-ray "pure" CoO nanocrystals are a unique composite structure with a CoO core surrounded by an extremely thin Co 3O 4 surface layer, which is likely a consequence of the surface passivation of CoO nanocrystals from the air oxidation at room temperature. The CoO core shows a particle size of 22 or 280 nm, depending on the types of the precursors used. This composite nanostructure was initiated as a catalytic additive to promote the thermal decomposition of ammonium perchlorate (AP). Our preliminary investigations indicate that the maximum decomposition temperature of AP is significantly reduced in the presence of CoO/Co 3O 4 composite nanocrystals and that the maximum decomposition peak shifts toward lower temperatures as the loading amount of the composite nanocrystals increases. These findings are different from the literature reports when using many nanoscale oxide additives. Finally, the decomposition heat for the low-temperature decomposition stages of AP was calculated and correlated to the chemical nature of the CoO/Co 3O 4 composite nanostructures.     

闽西晚中生代基性脉岩稀土元素地球化学特征

利用稀土元素特征对闽西基性脉岩的成岩方式和岩浆演化机制进行探讨. 闽西基性岩脉的稀土元素参数与常量元素的协变关系表明岩浆在上升侵入过程中可能没有发生地壳混染作用,在成岩过程中结晶分异作用可能不明显;多种稀土元素协变关系表明闽西基性脉岩的成岩机制可能为上地幔部分熔融作用,基性脉岩的地幔源区可能曾经遭受过俯冲流体交代富集作用,这种交代可能与古太平洋板块俯冲密切相关,软流圈地幔上涌导致地壳拉张作用的发育.     

悬浮液进样原子吸收光谱法测定核桃粉中钙和镁

采用悬浮液进样技术,原子吸收光谱法测定核桃粉中钙和镁的含量.将核桃粉悬浮于琼脂胶体中制成悬浮液,直接喷入空气-乙炔火焰,用标准加入法测定,并将测定结果与灰化法测定结果进行了比较,经 t 检验,在显著性水平α=0.05 时两种方法无显著性差异,相对标准偏差小于4.5%,检出限分别为 0.11 mg·L-1和 0.045 mg·L-1.     

The effect of MWS polarisation on the morphology and electro-optical behaviour of normal-mode polymer-stabilised cholesteric textures

We investigate the process and the resulting properties of the curing electric-field-induced segregation of reactive monomers (containing polar groups) in a host liquid crystal. The obtained dielectric spectrum of these cholesteric liquid crystals (CLCs) reveals polarisation at low frequencies. This is a strong indication that charge carriers accumulate at the interface between the sample and the electrodes in these compounds and consistent with Maxwell–Wagner–Sillars (MWS) polarisation. A polymer film forms on the substrate with its thickness determined by the MWS polarisation strength. The SEM images show that the polymer network becomes less dense when MWS polarisation increases. The results are a higher operating voltage and faster response time.     

AO-resistant properties of polyimide fibers containing phosphorous groups in main chains

A series of polyimide fibers containing phosphorus element derived from (3-aminophenyl) methyl phosphine oxide (DAMPO) diamine was exposed to an artificial atomic oxygen environment which simulated the space environment in low earth orbit (LEO). The mass loss, surface morphology, chemical composition, and mechanical properties of the fibers before and after atomic oxygen (AO) exposure were compared in detail with a blank sample. Results showed that the phosphor-containing fibers demonstrated lower mass change and less tensile strength reduction. SEM results showed that the fibers with phosphorous element had relatively dense surface after AO exposure. Meanwhile, XPS results indicated that a passivated phosphate layer, which could protect the following under-layer from attacking by AO, was formed on the surface of the fibers. These results indicated that the incorporation of diamine (DAMPO) into the main chains could protect the fibers for avoiding further erosion from AO exposure. Hence, the phosphor-containing PI fibers exhibits potential application in space fields.