Sensitive determination of phloroglucinol in human plasma by liquid chromatography-tandem mass spectrometry

Summary A sensitive and selective liquid chromatographic method coupled with tandem mass spectrometry (LC-MS-MS) was developed for the quantification of phloroglucinol in human plasma. Resorcinol was used as internal standard, with plasma samples extracted using ethyl acetate. A centrifuged upper layer was then evaporated and reconstituted with mobile phase. The reconsituted samples were injected into a C₁₈ XTerra MS column (2.1×100 mm) with 3.5 μm particle size. The analytical column lasted for at least 500 injections. The mobile phase was 15% acetonitrile (pH 3.0), with a flow rate at 100 μL min¹. The mass spectrometer was operated in positive ion mode using electrospray ionization. Using MS-MS in multiple reaction monitoring (MRM) mode, phloroglucinol was detected without severe interferences from the plasma matrix. Phloroglucinol produced a parent molecule ([M+H]⁺) atm/z 127 and a corresponding product ion atm/z 8l. Detection of phloroglucinol in human plasma was accurate and precise, with quantification on limit at 0.5 ng mL¹. The method has been successfully applied to a study of phloroglucinol in human specimens.     

Ultratrace determination of phosphorus in ultrapurified water by a slope comparison method

The analytical method for the determination of phosphorus in ultrapurified water was developed. Ultrapurified water was evaporated to concentrate phosphorus and the final sample volume for analysis was 10 ml. In 0.55 mol l⁻¹ HCl, orthophosphate forms molybdophosphate, and then the molybdophosphate forms ion associate with Malachite Green (MG), which can be collected on a tiny membrane filter (diameter: 5 mm, and effective filtering diameter: 2 mm). After the ion associate on the membrane filter is dissolved together with the membrane filter in 1 ml of methyl cellosolve (MC), the absorbance of MC solution is measured at 627 nm by a flow injection-spectrophotometric detection technique. When 10 ml of the sample solution was used for the procedures and absorbance measurement, the calibration graph is linear up to about 500 ng l⁻¹ of phosphorus and the detection limit was 8 ng l⁻¹ (S/N=3). For the determination of phosphorus in an ultrapurified water, 10-40 ml of sample solutions were transferred into poly(tetrafluoroethylene) (PTFE) beaker and evaporated to 5 ml or to dryness. To them, 0.003 mol l⁻¹ HCl was added to get 10 ml of final solution, which was used as sample. Phosphate is determined by comparing the slope of the varied sample volume after evaporation/concentration with a slope of the standard calibration graph (a slope comparison method: SCM). The SCM enables to evaluate the concentration of phosphate in ultrapurified waters more sensitively and accurately.     

Enhancement of long-term stability of pentacene thin-film transistors encapsulated with transparent SnO2

The long-term stability of pentacene thin-film transistors (TFTs) encapsulated with a transparent SnO₂ thin-film prepared by ion beam-assisted deposition (IBAD) was investigated. After encapsulation process, our organic thin-film transistors (OTFTs) showed somewhat degraded field-effect mobility of 0.5 cm²/(V s) that was initially 0.62 cm²/(V s), when a buffer layer of thermally evaporated 100 nm SnO₂ film had been deposited prior to IBAD process. However, the mobility was surprisingly sustained up to 1 month and then gradually degraded down to 0.35 cm²/(V s) which was still three times higher than that of the OTFT without any encapsulation layer after 100 days in air ambient. The encapsulated OTFTs also exhibited superior on/off current ratio of over 10⁵ to that of the unprotected devices (∼10⁴) which was reduced from ∼10⁶ before aging. Therefore, the enhanced long-term stability of our encapsulated OTFTs should be attributed to well protection of permeation of H₂O and O₂ into the devices by the IBAD SnO₂ thin-film which could be used as an effective inorganic gas barrier for transparent organic electronic devices.     

对引进离子注入机损坏部件进行国产化替换的尝试

国内引进了不少离子注入机,维修问题日渐重要。对其损坏部件,用国产配件进行替换,不乏为又快又省的维修方法。本文叙述了八年多来,我们在维修IM—200M型离子注入机的实践中,对损坏的吸极电源、氟里昂热交换器和化学机械泵等重要部件,用自制的或改制的国内配件进行替换,从而保证了设备安全运行二万五千多小时,注入八万五千多块硅及GaAs靶片,完成了集成电路研制和开发任务。     

铝栅自对准工艺

铝栅自对准电路具有集成度高和性能价格比高等优点。本文从离子注入与合金(退火)两方面着手,研究铝栅自对准工艺。成功地研制出可与国外样品互换的铝栅自对准电路。     

热水解离子色谱法测定岩石样品中的氯和硫

研究开发了一种热水解离子色谱法测定岩石样品中的氯和硫的方法技术。所研究开发的方法具有灵敏、高效、无干扰和准确的特点。实验研究和选择了热水解离子色谱测定的最佳工作条件。用测定的方法对6个国家一级岩石地球化学标准物质GSR1－6进行了分析测定，并在研究我国东部上地壳区域元素丰度实践中测定了2000件岩石样品。测定结果表明，测定值与标准物质的标准值一致。该方法的检出限分别国；氯31×10^-6。方法的精密度（RSD，％）对氯含量水平为40×10^-6，硫酸根含量水平180×10^-6时分别为6.1%和3.0%。     

Electrically driven capillary size exclusion chromatography

Summary Electrically driven size exclusion chromatography (ED-SEC) of polystyrenes in packed capillaries using dimethylformamide as solvent is demonstrated. The efficiency and retention behaviour of polystyrenes under pressure and electro drive were investigated. Under pressure drive the plate height (H) increases steadily with increasing linear velocity (u) whereas under electro drive the H-u curves largely coincide and are very flat. At higher velocities the plate heights are about 50% smaller with electro drive than with pressure drive. Calculations show that with increasing ionic strength, the flow through the particles may increase causing a clear diminishing of the elution window.     

Corrosion effects of nuclear tracks in polymers

Usually ion tracks are studies ex-situ, i.e. after removal of the ion-irradiated sample from the evacuated irradiation vessel. The exposure to ambient air leads to degradation effects which are frequently neglected and consequently have been studied rarely. They have never been explained consistently. In this work we compile and discuss them in the frame of today's general understanding of ion tracks in polymers. It appears that some pristine polymers such as polyethylene are covered by a surface layer which is badly permeable for gaseous contaminants. Ion irradiation leads to destruction of this protective layer so that oxygen and moisture from the ambient air can easily penetrate through the ion tracks, and eventually even into the surrounding pristine material. Moisture absorption along the tracks gives rise to some faint conductivity. Oxygen uptake adds new trapping centers to the existing ones along the tracks, so that on one hand an increased dopant uptake capability is recorded, and on the other hand oxygen-sensitive mobile dopants are immobilized along the ion tracks. Photooxidation processes contribute to the fading of the optical blackening of irradiated polymers.