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81.
Koichi Machida Akira Kotani Yuzuru Hayashi Hideki Hakamata 《Journal of mass spectrometry : JMS》2022,57(8):e4877
ISO 11843 part 7 (ISO 11843-7) can provide a standard deviation (SD) of area measurements of a target peak through the stochastic behaviors of instrumental noises. The purpose of this study is to demonstrate that ISO 11843-7 can be applied to assess repeatability in an isocratic liquid chromatography–tandem mass spectrometry (LC–MS/MS) system without repetitive measurements. The relative standard deviation (RSD) of the peak area of ergosterol picolinyl ester, which was used as an example, on a multiple reaction monitoring (MRM) chromatogram was determined by ISO 11843-7. The RSD by ISO 11843-7 (N = 1) was within a 95% confidence band of the RSD by repetitive measurements (N = 6). Moreover, the effects of digital smoothing, such as moving average, were also examined on the repeatability assessment in LC–MS/MS by ISO 11843-7. From the results of the comparisons of the RSDs obtained by ISO 11843-7 and the repetitive measurements, it was shown that suitable RSDs of the peak area were obtained from the smoothed MRM chromatograms by the moving average for narrow data point windows (e.g., one-sixth of the peak width). In conclusion, the utility of repeatability assessment based on ISO 11843-7 has been expanded for the validation of an LC–MS/MS system. 相似文献
82.
Hasegawa H Shinohara Y Hashimoto T Matsuda R Hayashi Y 《Journal of chromatography. A》2006,1136(2):226-230
An equation is theoretically derived which describes the relative standard deviation (RSD) of the amount ratios of analyte to its isotope-labeled variant in gas chromatography/mass spectrometry (GC/MS) using the stable isotope dilution method. The determination of methyltestosterone is taken as an example. The uncertainty equation proposed is justified by comparing the theoretical RSD values with the experimental RSD values obtained by replication over a wide range of analyte amount. The detection limit and quantitation limit are estimated from the continuous plot (precision profile) of the theoretical RSD against analyte amount. 相似文献
83.
A series of dihalodiaryl(acetylacetonato)antimony(V) compounds, (p-Y-C6H4)2SbX2Acac (X=F, Cl, Br; Y=NO2, Cl, H, CH3, CH3O), were prepared. All of these compounds are monomeric and exist in solution as a mixture of two isomers both with chelated hexacoordinate configurations. From the temperature- and solvent-dependent PMR spectra of these compounds, it is concluded that the two isomers are in equilibrium in solution. The assignments of the PMR signals to the isomers were made by considering the effects of solvent and the substituents X and Y on the spectra. 相似文献
84.
A new dimeric sesquiterpenoid with two eudesmane skeletons through a urea linkage, halichonadin A (1), as well as three new eudesmane sesquiterpenoids having a carbamate, an isonitrile, or an amino functionality, halichonadins B (2), C (3), and D (4), respectively, have been isolated from a marine sponge Halichondria sp., and the gross structures and relative stereochemistry of 1-4 were elucidated on the basis of spectral data and chemical means. 相似文献
85.
86.
Yuzuru Sanemitsu Yoskinori Nakayama Masao Shiroshita 《Journal of heterocyclic chemistry》1981,18(5):1053-1054
3,4-Dihydro-1,2,4-triazin-5-(2H)ones were prepared by the reduction of 3-methylthio-1,2,4-triazin-5-(2H)-ones with sodium borohydride in dimethylformamide. The synthesis appears to be general. 相似文献
87.
Optically and biologically active (IR,5S,7R)-(+)-exo-brevicomin was synthesized in the six-step sequence starting from diethyl (S,S)-(−)-tartrate. 相似文献
88.
Toshikazu Kurosaki Kyu Wan Lee Makoto Okawara 《Journal of polymer science. Part A, Polymer chemistry》1972,10(11):3295-3310
Polymers having stable nitroxyl free radicals, poly-4-methacryloylamino- and poly-4-methacryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyls, were synthesized from their precursor polymers by oxidizing them in a methanolic solution of hydrogen peroxide. The precursor polymers were prepared by radical polymerization of 4-methacryloyl-amino/oxy-2,2,6,6-tetramethylpiperidines in various solvents. These polymerizations in acetic acid were found to yield polymers of high molecular weight. The copolymers of the precursor monomers with styrene and methyl methacrylate were also prepared as precursor copolymers. These precursor polymers of a piperidine type were converted to the polymers having stable nitroxyl free radicals by the hydrogen peroxide method. In this report, it was assumed that the post-oxidation reaction introduced a nitroxyl group smoothly and quantitatively at room temperature. Elucidations of the stable radical formation and the electron spin behavior of the stable radical polymers were made in terms of elemental analyses, infrared, ultraviolet, and ESR spectroscopy. 相似文献
89.
Gohei Yoshida Hideo Kurosawa Rokuro Okawara 《Journal of organometallic chemistry》1977,131(2):309-315
Oxidative addition of ClCH2SCH3 to PtL4 afforded trans-PtL2(CH2SCH3)Cl (Ia, L = Ph3P;Ib, L = MePh2P). Treatment of I with NH4PF6 or Et3OBF4 in CH2C12 gave ionic species, [PtL2(CH2SCH3)]X (II, L = Ph3P, MePh2P, X = BF4, PF6), while similar treatment with MeSO3F in benzene yielded a new type of stable dimethylsulfonium methylide—platinum complex, trans-[PtL2(CH2SMe2)Cl] SO3F (IIIa, L = Ph3P; IIIb, L = MePh2P). Action of H2O2 on Ia gave [Pt(Ph3P)(μ-CH2SCH3)C1]2 (IV) and its triphenylarsine analog, [Pt(Ph3As)(μ-CH2SCH3)C1]2 (V) was prepared in one step by oxidative addition of ClCH2SCH3 to Pt(AsPh3)4. The structural difference between [Pt(Ph3P)(μ-CH2SCH3)C1]2 and Pd(Ph3P)- (CH2SCH3)C1 is discussed in terms of the difference in the ionization potential from d10 to d8 electronic state of metals. 相似文献
90.
Yuzuru Sanemitsu Yoshinori Nakayama Masao Shiroshita 《Journal of heterocyclic chemistry》1983,20(6):1671-1675
A regioselective synthesis of 2-aminotriazinones 6a-d is reported, by reaction of 3-methylthio-1,2,4-triazinones 5a-d with O-(2,4-dinitrophenyl)hydroxylamine (2) as an amino-transfer agent. A spectroscopic study and an unequivocal synthesis of 2-amino-4-methyl-6-phenyl-1,2,4-triazinedione ( 11a ) has shown the site of amination to be N2 of the 1,2,4-triazinone ring. Subsequent reaction of 2-amino-1,2,4-triazinones 6a-b with amines, followed by ring closure with aliphatic acids provided [1,2,4]triazolo[2,3-b][1,2,4]triazine-7(1H)ones 13a-e. Conversion of [1,2,4]triazolo[2,3-b][1,2,4]triazinone 13c to unsubstituted [1,2,4]triazolo[2,3-6][1,2,4]triazine (15) was attained. 相似文献