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991.
A sensitive and specific method was developed for the determination of sophoridine (SRI), sophocarpine (SC) and matrine (MT) in rabbit plasma by HPLC-MS. After an administration of Kuhuang by injection, blood samples were collected and extracted with methanol. The extract solutions were analysed by HPLC-MS method. The separation was performed on a ZORBAX Extend-C18 column using methanol/water/diethylamine (50:50:0.07, v/v/v) as mobile phase. The quinolizidine alkaloids were detected by using mass spectrometry in the SIM mode. There was a good linear relationship between peak area and concentration of analytes over the concentration range of 13.2–995.0 ng mL–1 for SRI, 7.0–530.0 ng mL–1 for SC and 8.8–655.0 ng mL–1 for MT, respectively. The absolute recovery of this method was more than 57% for SRI, 87% for SC and 91% for MT. The accuracy of assay was more than 90%. The limits of detection (LODs) were 6.8 ng mL–1 for SRI, 3.5 ng mL–1 for SC and 4.2 ng mL–1 for MT, respectively. The limits of quantitation (LOQs) were 13.2 ng mL–1 for SRI, 7.0 ng mL–1 for SC and 8.8 ng mL–1 for MT, respectively. The intra-day and inter-day coefficients of variation (RSDs) were less than 10.1, 6.3 and 5.8% for SRI, SC and MT, respectively. The developed method was applied to determine the concentration–time profiles of SRI, SC and MT in rabbit plasma after injection of Kuhuang. 相似文献
992.
Xu X Zhao Z Song P Zhou G Xu J Deng P Bourdet G Chanteloup JC Zou JP Fulop A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(11-12):2444-2447
Infrared (1.2-1.6 microm) luminescence in a ytterbium aluminium garnet (YbAG) crystal, doped with Cr (0.05at.%) ions, was investigated under CW laser diode pumping (lambda=940 nm). The Cr4+ emission band was observed with its peak at 1.34 microm and measured to be about 1.3 times with respect to Yb3+ IR luminescence (lambda=1.03 microm). We demonstrate that for the excitation wavelength of 940 nm Yb3+ ions act as sensitizers of the 3B2(3T2)-3B1(3A2) emission of Cr4+ ions. This crystal is promising as a high-efficient system for tunable laser (1.2-1.6 microm) output. 相似文献
993.
The complex, bis[N‐6‐aminopyridyl‐N‐(1S)‐(+)‐10‐camphorsulfonylamino]palladium, Pd[(S)‐APCS]2, 1 , was prepared by reaction of 2‐[(1S)‐(+)‐10‐camphorsulfonamino]‐6‐aminopyridine with PdCl2 in THF. Complex 1 has been characterized by spectroscopic methods and its structure has been determined by X‐ray crystallography. Crystal data: space group C2, a= 16.082 (2), b = 17.104 (2), c = 13.051 (2)Å, β = 99.95 (1)°, V = 3535.9 (8) Å3, Z = 2 with final residuals R1 = 0.0491 and wR2 = 0.0944. Two independent molecules, (S,S)‐Pd[(S)‐APCS]2, 1a , and (R,R)‐Pd[(S)‐APCS]2, 1b , were found in each asymmetric unit, which exchange to each other via a series of nitrogen inversion and C‐C bond rotation. The inversion energy (ΔGc1≠) and the energy barrier (δGc2≠) were 11.5 ± 0.1 Kcal mol?1 at 246 K and 9.8 ± 0.1 Kcal mol?1 at 199 K, respectively, calculated by dynamic NMR data. 相似文献
994.
A series of near infrared (NIR) absorbing dinuclear ruthenium dicarbonylhydrazine complexes (DCH-Ru),[{Ru(bpy)_2)_2μ-DCH]~(n ) (where bpy = 2,2'-bipyridinc and n = 2, 3 or 4), were prepared. The DCH-Ru complexes areelectrochromic in the NIR region with a high absorption coefficient at 1550-1600 nm typically over 10000 M~(-1)cm~(-1). DCH-Ru complex polymers with good NIR electrochromic properties were also obtained and processed to make a device foroptical attenuation at a wavelength of 1550 nm. The potential of these DCH-Ru polymers for use in a variable opticalattenuator has been demonstrated with an attenuating power at the 1550-nm telecommunication wavelength over 7.0 dB permicron of polymer film thickness. Other classes of NIR active materials are the pentacenediquinones and the correspondingpoly(ether pentacenediquinone)s. These polymers can be electrochemically reduced to the corresponding semiquinone(radical anion) having NIR absorption within a telecom window (e. g., 1310 nm). 相似文献
995.
This study presents a novel, simple and rapid procedure for isomer differentiation by combining gas chromatography (GC), a selective self-ion/molecule reaction (SSIMR) and tandem mass spectrometry (MS/MS) in an ion trap mass spectrometer (ITMS). SSIMR product ions were produced from four isomers. For aniline, SSIMR induces the formation of the molecular ion, [M+H](+), [M+CH](+), adduct ions of fragments ([M+F](+), where F represents fragment ions) and [2M-H](+). 2 and 3-Picoline produce [M+H](+), [2M-H](+) and [M+F](+), while 5-hexynenitrile produces [M+H](+), [M+F](+) and [2M+H](+) ions. The proposed method provides a relatively easy, rapid and efficient means of isomer differentiation via a SSIMR in the ITMS. Typically, isomer differentiation can be achieved within several minutes. The superiority of the SSIMR technique for isomer differentiation over electronic ionization (EI) is also demonstrated. 相似文献
996.
A method for the qualitative and quantitative analysis of volatile organic compounds (VOCs) in the air of class-100 clean rooms at semiconductor fabrication facilities was developed. Air samples from two semiconductor factories were collected each hour on multisorbent tubes (including Carbopack B, Carbopack C, and Carbosieve SIII) with a 24-h automatic active sampling system and analyzed using adsorption/thermal desorption coupled with gas chromatography-mass spectrometry. Experimental parameters, including thermal desorption temperature, desorption time, and cryofocusing temperature, were optimized. The average recoveries and the method detection limits for the target compounds were in the range 94-101% and 0.31-0.89 ppb, respectively, under the conditions of a 1 L sampling volume and 80% relative humidity. VOCs such as acetone, isopropyl alcohol, 2-heptanone, and toluene, which are commonly used in the semiconductor and electronics industries, were detected and accurately quantified with the established method. Temporal variations of the analyte concentrations observed were attributed to the improper use of organic solvents during operation. 相似文献
997.
The Staudinger reaction of fluoroalkylazides were studied. A series of N-fluoroalkylimines were synthesized via aza-Wittig reaction of N-fluoroalkyliminophosphoranes. The N,N′-difluoroalkylated carbodiimide was also synthesized via the reaction of N-fluoroalkyliminophosphoranes with carbon dioxide or carbon disulfide. 相似文献
998.
In order to determine the elemental concentrations of three new soil standard reference materials SRMs 2709, 2710 and 2711 from the National Institute of Standards and Technology (NIST), a comparative study of different medium-lived neutron activation analysis methods was carefully performed. Three irradiation conditions (1-hour thermal, 1-hour epithermal and 5-minute epithermal) and two counting modes (normal and Compton suppression) have been evaluated for following ten elements: As, Au, Cd, Ga, K, La, Mo, Sb, Sm, and W. The results show that the method of 5-minute epithermal and a 1-day decay is the optimum way to analyze Ga, while the addition of the Compton suppression is very beneficial for the determination of K. Using the Compton suppression system in conjunction with the 1-hour epithermal and a 1-week decay, is ideal to determine Au, Cd, Mo and W, while routine 1-hour thermal and a 1-week decay, is adequate to determine As, Sb, Sm and La in concentrations found in soil. 相似文献
999.
C. Allen Chang Tamar E. Woodhouse Qihui Wu Ceshing Sheu Katherine McManus 《中国化学会会志》1988,35(4):253-260
Substitution-inert metal complexes, [Co(edda)(H2O)2]+, (Co(edda)(en)]+, [Co(edda)(dmen)]+, [Co(en)2-(gly)]2+, [Co(en)2(acac)]2+, and [Co(trien)(gly)]2+ in their nitrate salt solutions are used as eluents in nonsuppressed cation chromatography (where edda = ethylenediamine-N,N′-diacetic acid, en = ethylenediamine, dmen = N,N′-dime-thylethylenediamine, gly = glycine, acac = acetylacetone, and trien = triethylenetetraamine). It is found that all the mono- and di-valent charged complexes can be used to separate alkali and alkaline earth metal cations, respectively. The separations for monovalent cations are sometimes comparable to those using ultrapure HNO3 solutions. However, the divalent Ca2+ and Sr2+ ions cannot be resolved using the metal complex eluents. On the other hand, a selected, direct non-suppressed IC separation of zinc(II) and cadmium(II) ions is demonstrated for the first time using a substitution-inert metal complex eluent and a conductivity detector. Comparisons of these eluents with those reported previously, i. e. HNO3 and ethylenediammonium salt solution are made and explanations are proposed to account for the different selectivities observed where possible. The future development of this technique is also briefly discussed. 相似文献
1000.
Tiantian Liu Xiaojie Chen Juan Zhao Weichun Wei Zhu Mao William Wu Shibo Jiao Yang Liu Zhiyong Yang Zhenguo Chi 《Chemical science》2021,12(14):5171
Pure organic emitters with full utilization of triplet excitons are in high demand for organic light-emitting diodes (OLEDs). Herein, through modulation of electron donors and introduction of phenyl rings as π spacers, we present three pure organic fluorophores (BCz, BTCz and BPTCz) with the hybridized local and charge-transfer (HLCT) excited state feature for OLED fabrication. Importantly, the introduction of π spacers in BPTCz not only enhances locally excited character with a fast radiative decay but also promotes intermolecular interactions to suppress non-radiative decays, contributing to a high solid-state fluorescence efficiency over 90%. Significantly, BPTCz not only endows its doped OLEDs with an external quantum efficiency (EQE) up to 19.5%, but also its non-doped OLED with a high EQE of 17.8%, and these outstanding efficiencies are the state-of-the-art performances of HLCT-based OLEDs.Three purely organic fluorophores with a hybridized local and charge-transfer excited state feature are presented and enabled organic light-emitting diodes with record high external quantum efficiencies close to 20%. 相似文献