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51.
52.
Maria F. Ebel H. Ebel K. Hirokawa 《Spectrochimica Acta Part B: Atomic Spectroscopy》1982,37(6):461-471
A comparison between X-ray fluorescence analysis (XRFA) and X-ray photoelectron spectroscopy (XPS) indicates the applicability of these two methods as relative and absolute techniques. For XPS the absolute field of application should be preferred. An improvement of the Hirokawa-Ebel method (an absolute XPS analysis) is presented in this paper. It is shown that the knowledge of the inelastic mean free paths of the photoelectrons (IMFP) is no longer required, but the energy dependence of the IMFPs can be used as a basis. This guarantees simplicity and much more universal applicability. 相似文献
53.
Summary The determination of nitrogen in steels was investigated by low voltage condensed spark discharge and far ultraviolet vacuum spectroscopy. The excitation conditions were 1,000V, 193, 63 F and 50H in helium atmosphere of 700 mm Hg. Nitrogen contents from 20 ppm to 100 ppm in steel could be determined with the line pair of N I 1,745 Å/Fe I 1,876 Å or N I 1,742 Å/Fe I 1,876 Å.
Zusammenfassung Zur Bestimmung von Stickstoff (20–100 ppm) in Stählen wurde eine UV-vakuumspektrometrische Methode mit Niederspannungs-Funkenentladung benutzt. Die Entladungsbedingungen waren: 1000 V, 193 , 63 F und 50 H, unter Heliumatmosphäre von 700 mm Hg; verwendet wurden die Linienpaare N I 1,745 Å/Fe I 1,876 Å oder N I 1,742 Å/ Fe I 1,876 Å.相似文献
54.
Operational modes for transient isotachophoretic preconcentration capillary zone electrophoresis (tr-ITP-CZE) were studied by using 5 microM and 0.5 microM rare earth mixtures as analytes in comparison with field-enhanced sample stacking. After examination of several operational modes for tr-ITP, it was found that tr-ITP effectively occured even if both the leading electrolyte and the terminating electrolyte were injected after the sample plug. This was explained as the result of a field-enhanced stacking for both sample components and the leading and terminating ions. The observed theoretical plate numbers were 4-20 times higher than those obtained by normal stacking; and the estimated low limit of detectable concentration of rare-earth elements (REE) was ca. 0.1 microM which was 2.5 times lower compared to normal stacking. For the 0.5 microM sample, a concentration factor of 20 000 could be achieved after only tr-ITP. 相似文献
55.
T Hirokawa K Nishimoto Y Jie K Ito F Nishiyama N Ikuta S Hayakawa 《Journal of chromatography. A》2001,919(2):417-426
Mobilities of 16 anions of rare-earth-EDTA 1:1 chelate (RE-EDTAs) were isotachophoretically measured by using two leading electrolytes (pH 3.6 and 6.0) in order to assess their separation behavior. The leading electrolyte was 20 mM hydrochloric acid. The pH of the solution was adjusted to 3.6 by adding beta-alanine and to 6.0 by adding histidine. The obtained mobilities were very close to each other in the range 20.1x10(-5)-21.9x10(-5) cm2 V(-1) s(-1) with the minimum mobilities for Pr-EDTA and Nd-EDTA for pH 3.6 and 6.0, respectively, and pH dependence was hardly observed. On the basis of the above knowledge. minor rare-earth elements in a standard iron ore sample were determined as RE-EDTAs by bidirectional isotachophoresis-particle-induced X-ray emission (PIXE), where the Fe(II) matrix digested by alkali fusion was separated as Fe(II)Phen3(2+) (phen = 1,10-phenanthroline). Since 5% of the total iron was still detected as Fe(III)EDTA- and might disturb PIXE analysis of RE-EDTA-, itaconic acid was used as the spacer for Fe(III)EDTA- and RE-EDTA-. The fractions of RE-EDTA- were successfully analyzed off-line by a multielemental analytical method, PIXE [analytical result (3.62% (w/w) as RE2O3]; the nominal value was 3.37% (w/w) as RExOy. 相似文献
56.
The first enantioselective total synthesis of rumphellaone A, a cytotoxic 4,5-seco-caryophyllane isolated from the gorgonian coral Rumphella antipathies, has been achieved from a known olefinic alcohol by a 16-step sequence involving Stork's epoxy nitrile cyclization as the key step to concomitantly install a cyclobutane ring and three contiguous stereogenic centers contained in the molecule. 相似文献
57.
58.
Xiaoxue Ye Satomi Mori Mihoro Yamada Junji Inoue Zhongqi Xu Takeshi Hirokawa 《Electrophoresis》2013,34(4):583-589
Aiming to high sensitivity DNA analysis by CGE, electrokinetic supercharging (EKS) approach was adopted in this article. EKS is known as an online preconcentration technique that combines electrokinetic sample injection (EKI) with transient ITP (tITP). Herein, two factors of buffer viscosity and electrode configuration were studied to further improve EKS performance. An ultralow‐viscosity Tris‐Boric acid‐EDTA (TBE) buffer solution, consisted of 2% low‐molecular‐weight hydroxypropyl methyl cellulose (HPMC) and 6% mannitol and with pH 8.0 adjusted by boric acid, was applied. The boric acid would make a complex with mannitol and generates borate polyanion, which acts as the leading ion for tITP process. The new electrode configuration, a Pt ring around capillary, was modified on Agilent CE system to lead large amount sample introduction during EKS. The standard DNA sample of φX174/HaeIII digest was used to evaluate the qualitative and quantitative abilities of the proposed strategy. The 170 000‐fold highly diluted sample at concentration of 3.0 ng/mL was enriched by EKS and detected by normal UV detection method. The obtained LOD of the weakest peak of 72 bp fragment was around 7.7 pg/mL, apparently improved more than 10 000‐fold in comparison with conventional CGE with UV detection. 相似文献
59.
60.
A Glancing-Incidence and Take-off X-Ray Fluorescence (GIT-XRF) apparatus with which both incident angle of primary X-ray and take-off angle of fluorescent X-rays can be controlled has been newly developed for characterizing surfaces and interfaces. Using this apparatus, Ni/Mn multilayer samples were evaluated obtaining Take-off-Angle-Dependent X-Ray Fluorescence (TAD-XRF) curves at arbitrary incident angles of primary X-ray. In particular, we could obtain information on the near surface by measuring TAD-XRF curves at the incident angle less than the critical angle of total reflection for primary X-rays. 相似文献