单扫描极谱法测定注射液及血清中维生素K1

建立了维生素K1的极谱测定方法.在0.05 mol·L-1 NH4Cl-NH3(pH 8.58)缓冲溶液中,维生素K1可产生一极谱还原峰,峰电位Ep为-0.39 V ;其二阶微分峰峰电流ip″与维生素K1的浓度在1.1×10-7 ～2.2×10-5 mol·L-1范围内呈线性关系,相关系数r=0.998 6(n= 9 );方法的检出限为4.0×10-8 mol·L-1.13次平行测定2.2×10-5 mol·L-1维生素K1还原波二阶导数峰峰电流ip″的相对标准偏差(RSD)为1.83%.本法可直接用于注射液及血清中维生素K1含量的测定.     

Separation of L-DOPA and four metabolites in plasma using a porous graphitic carbon column in capillary liquid chromatography

Summary A sensitive HPLC method with marbofloxacin (MAR) as internal standard and fluorescence detection is described for the analysis of ofloxacin (OFL) enantiomers in plasma samples. Plasma samples were prepared by adding phosphate buffer (pH 7.4, 0.1m), then extracted with trichloromethane.S-OFL,R-OFL, and the internal standard were separated on a reversed-phase column with water-methanol, 85.5∶14.5, as mobile phase. The concentrations ofS-OFL andR-OFL eluting from the column (retention times 7.5 and 8.7 min, respectively) were monitored by fluorescence detection withλ _ex = 331 andλ _em = 488 nm. The detection and quantitation limits were 10 and 20 ng mL⁻¹, respectively, forS-OFL and 11 and 21 ng mL⁻¹ forR-OFL. Response was linearly related to concentration in the range 10 to 2500 ng mL⁻¹. Recovery was close to 93% for both compounds. The method was applied to determination of the enantiomers of OFL in plasma samples collected during pharmacokinetic studies.     

Methane polymerization with a hollow cathode: Influence of the cathode metal

Methane, mixed with argon, has been polymerized by means of a hollow-cathode discharge system. Two types of cathodes were studied; one was made of a solid solution of 81% tungsten and 19% platinum, while the other was of pure tungsten. Under identical operating conditions, a higher polymer yield was found in the case of the platinum cathode (90% against 70% for tungsten). The work function of the solid solution was estimated to be 6.3 eV, compared with 4.4 eV for tungsten. In terms of the data available, the thermionic current, which is the main source of energetic electrons, is about one order of magnitude lower for the solid solution cathode when compared with the tungsten cathode thermionic current. However, the polymer yield observed is higher in the former case. The concentration of the CH species in the hollow cathode was found to differ greatly for the cathodes tested and was about 5 times higher in the case of tungsten-platinum cathodes. Since no excited platinum vapor could be detected in the gas phase, the increase in CH concentration was attributed to a catalytic effect of the cathode inside surface. An evaluation of the plasma polymer deposition rate yields 70 nm·s^–1 for the platinum-tungsten type hollow cathode and 42 nm·s^–1 for the tungsten one. In both cases, the deposition rate is much higher than those obtained from the most widely used methods for plasma polymer deposition (0.10–1.0 nm·s^–1) implying methane-argon mixtures, and is comparable to the results obtained with a new type of plasma polymer deposition reactor described in the literature.     

Simultaneous quantitative measurement of a new platelet activating factor antagonist (BN 50730) and its two main metabolites in human plasma and urine by LC-MS

Summary A simple and sensitive assay has been developed for the quantitative measurement of a new platelet activating factor antagonist (BN50730), and its two main metabolites (BN50727 and BN50922), at the picomole level in human plasma and urine. The three compounds of interest and the internal standard (BN50765) were measured by combined LC-negative chemical ionization MS. A simple solid-liquid extraction procedure was used to isolate the parent drug and the two metabolites. The MS was tuned to monitor the intense ionm/z 333 generated in the ion source by a dissociative capture process. The assay was on 1 ml plasma or 0.1 ml urine and the quantitation limit was calculated as 1 ng·ml^–1. The very low relative standard deviations and mean percentages of error calculated for within-day or between-day repeatability assays demonstrate the ruggedness of the technique for routine determination in biological fluids. Some preliminary results on the pharmacokinetics of the parent drug and its two main metabolites illustrate the applicability of this method.     

Selective permeation of CO2 through poly 2-(N,N-dimethyl)aminoethyl methacrylate membrane prepared by plasma-graft polymerization technique

A membrane having an amine moiety was prepared by plasma-grafting 2-(N,N-dimethyl)aminoethyl methacrylate (DAMA) onto a microporous polyethylene substrate. Permselectivity of the membrane for CO₂ over N₂ was achieved in both dry and water swollen conditions. When the CO₂ partial pressure in the feed gas was 0.047 atm, the selectivity of CO₂ over N₂ reached 130 for the highly swollen water containing membrane. This value was found to agree with that obtained with a mobile carrier membrane (supported liquid membrane) using DAMA as the carrier. The effects of several experimental conditions such as degree of grafting, feed partial pressure and temperature on the membrane performance were studied. It was suggested that the membrane acted as a fixed carrier membrane for CO₂ facilitated transport in under the dry condition and acted as a fixed reaction site membrane in the water swollen condition. The carrier transport mechanism is discussed for dry and aqueous membranes.     

Conductivities and silver electrode polarization resistance of solid electrolyte ceramics from ZrO2-Y2O3 powder synthesized in air plasma

Ceramic specimens have been obtained from the powder of ZrO₂-7.5 mol% Y₂O₃ having a specific surface area of 30 m²/g synthesized in air plasma. The novelty of this research lies in the fact that the plasma process makes it possible to prepare so-called nanopowders with a particle size less than 100 nm, possessing specific physical, chemical and technological properties. The sintered density of the specimens was 94–96% of the theoretical value, 6.001 g/cm³. The X-ray diffraction pattern of the specimens corresponded to a face-centered cubic lattice. Impedance in the frequency range of 100 Hz–15 MHz and d.c. polarization curves in a potential range of −10 to 10 mV were measured in the temperature range 200–850 °C in heating and cooling cycles. The intragrain, the grain boundary and the total bulk conductivities, the electrode polarization resistance and their activation energies were determined. The thermal stability of the studied system was proved in three measurement series up to 600–850 °C in heating and cooling cycles. The results obtained have shown that the conductivity of ZrO₂-7.5 mol% Y₂O₃ ceramics is not solely a function of temperature, but also depends on the previous thermal state of the ceramics. Received: 16 October 1997 / Accepted: 19 January 1998     

Dry etching of InGaP and AlInP in CH4/H2/Ar

Electron cyclotron resonance (ECR) plasma etching with additional rf-biasing produces etch rates 2,500 A/min for InGaP and AlInP in CH₄/H₂/Ar. These rates are an order of magnitude or much higher than for reactive ion etching conditions (RIE) carried out in the same reactor. N₂ addition to CH₄/H₂/Ar can enhance the InGaP etch rates at low flow rates, while at higher concentrations it provides an etch-stop reaction. The InGaP and AlInP etched under ECR conditions have somewhat rougher morphologies and different stoichiometries up to 200 Å from the sur face relative to the RIE samples.     

Untersuchungen zur mikroanalytischen Bestimmung der langkettigen Fetts?uren im Blut

Zusammenfassung Für die im Plasma an Albumin gebundenen sog. freien Fettsäuren (FFS) wird ein neues gas-chromatographisches Analysenverfahren vorgestellt. Das Probenvolumen beträgt 50 l Serum oder Plasma. Die Extraktion erfolgt in 1,1 ml CHCl₃/CH₃OH (21, v/v) mit n-Heptadecansäure als innerem Standard (0,05 Val C₁₇₀/ml). Nach Eindampfen am Rotationsverdampfer werden die FFS im verschlossenen Reaktionskölbchen mit 20 l CH₃J/Essigsäureäthylester (11, v/v) über festem K₂CO₃ bei 90°C 1 h verestert. Die Varianz des Verfahrens errechnet sich bei 15 Parallelbestimmungen zu 4,85%.Vortrag anläßlich der Tagung Spurenanalyse, 2. bis 5. April 1973 in Erlangen.     

微波诱导低级醇的等离子体化学反应

微波诱导低级醇的等离子体化学反应王真，洪品杰，张承聪，戴树珊（云南大学化学系，昆明，６５００９１）关键词微波，等离子体化学，低级醇等离子体能产生大量的活性自由基、亚稳态粒子和激发态离子，它所包含的能量传递过程和反应过程不仅与反应碰撞理论有关，而且还涉...