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71.
High-performance liquid chromatography with electrochemical detection (HPLC-ED) and combined gas chromatography--mass spectrometry in the single-ion monitoring mode (GC--MS-SIM) have been used for the determination of salsolinol, dopamine, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxyphenylethanol and norepinephrine in a selection of food and beverage samples. The unique specificity of the SIM mode allows a simple one-step extraction to be used even for complex sample matrices. We have been able to demonstrate the quantitative and qualitative advantages offered by GC--MS over HPLC--ED by direct comparison of the chromatographic data obtained. We demonstrate that the specificity of SIM and the benefits offered by the incorporation of deuterated internal standards make GC--MS-SIM the method of choice for valid identification and precise quantitation of salsolinol, dopamine and dopamine metabolites in a complex sample matrix. 相似文献
72.
A. Hudson M.F. Lappert J.J. Macquitty B.K. Nicholson H. Zainal G.R. Luckhurst C. Zannoni S.W. Bratt M.C.R. Symons 《Journal of organometallic chemistry》1976,110(1):C5-C8
The reassignment to a manganese(0) quartet state by C.L. Kwan and J.K. Kochi (J. Organometal. Chem., 101 (1975) C9) of the ESR spectrum obtained during photolysis of Mn2(CO)10 in THF is shown to be in error; computer simulation of the X-band spectrum and observation of the S-band spectrum confirm our previous assignment to sextet manganese(II) and chemical and IR evidence indicate the presence of [Mn(CO)5]? as a counter ion. 相似文献
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T. A. J. Nicholson 《The Journal of the Operational Research Society》1968,19(4):445-452
An efficient method is described for obtaining near-optimal solutions to planar travelling salesman problems. Firstly, the convex boundary of points is determined and this is subsequently deformed by an iterative process until all the points have been included in the tour. Results are good on some trial problems. 相似文献
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The ionicity of oxide and β- and β″-Al2O3 crystals is identified via Lorentz–Lorenz molar refractivity. The investigation was extended to sodium gallates, the refractivity and average refractive index of which are estimated. 相似文献
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The application of high-field Fourier transform nuclear magnetic resonance (NMR) spectroscopy to the analysis of biological fluids such as urine, plasma and bile is described. Applications include areas such as clinical chemistry, experimental and clinical toxicology and drug metabolism studies. In the case of proton NMR some means of attenuating or eliminating the interference due to water protons is required and suitable strategies for achieving this are discussed. The use of 2-dimensional NMR or solid-phase extraction/chromatography to enable the identification of unknowns is discussed and the potential usefulness of 19F NMR for studying the metabolism of fluorinated xenobiotics is highlighted. 相似文献
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