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This paper describes the use of water-in-oil (W/O) microemulsion eluents to achieve unique normal phase HPLC separations.
The effects of varying the oil type, co-surfactant, surfactant, use of mixed surfactant and water concentration upon the chromatographic
performance was assessed. Other parameters such as temperature and flow rate were also investigated. An optimised set of W/O
microemulsion HPLC (MELC) operating conditions was then applied to the separation of a range of acids, bases and neutral compounds.
The more water soluble compounds were more highly retained. W/O MELC was found to be especially suitable for determination
of water insoluble compounds. The drug content in bumetanide tablets was determined by W/O MELC with good linearity and accuracy.
The solubilising ability of the W/O microemulsion reduced sample preparation (precipitation and extraction) requirements compared
to conventional HPLC. The results obtained compared well with those obtained by a validated reverse phase HPLC method. It
is recommended that W/O MELC should be considered for routine applications, especially for the analysis of water insoluble
compounds in complex sample matrices. Further research is recommended to more definitely assess the operating parameters of
W/O MELC and to determine other applications. 相似文献
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Ferro-Luzzi M Bouwhuis M Passchier E Zhou Z Alarcon R Anghinolfi M van Bommel R Botto T van den Brand JF Buchholz M Bulten HJ Choi S Comfort J Dolfini S Ent R Gaulard C Higinbotham D de Jager CW van Klaveren EP Konstantinov E Lang J de Lange DJ Miller MA Nikolenko D Nooren GJ Papadakis N Passchier I Poolman HR Popov SG Rachek I Ripani M Six E Steijger JJ Taiuti M Unal O Vodanis N de Vries H 《Physical review letters》1996,77(13):2630-2633
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V. Weldon P. Pineda-Vadillo M. Lynch R. Phelan J. F. Donegan 《Applied physics. B, Lasers and optics》2012,109(3):433-440
The characteristics of a novel Discrete Mode laser diode are described with particular reference to its capability in spectroscopic based gas sensing. In this regard, its emission linewidth, Side Mode Suppression Ratio and tuneability are of particular note. The measured narrow linewidth of 550?kHz has applications with respect to spectrally narrow absorption features found, for example, in saturated absorption lines, in hyperfine structure of some rotational manifolds and in whispering gallery mode features associated with optical microspheres. Other notable measured characteristics show mode-hop-free temperature tuning of 11 nm at a linear tuning rate of 0.1 nm/°C and a Side Mode Suppression Ratio in the range 56 to 46 dB and a long term (72?hours) wavelength stability of 1?pm per day. In essence, this novel Discrete Mode laser displays excellent potential for diode laser based sensing applications in the near infrared. 相似文献
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J. D. Carey R. C. Barklie J. F. Donegan F. Priolo G. Franz S. Coffa 《Journal of luminescence》1998,80(1-4):297-301
Electron paramagnetic resonance (EPR) measurements have been used to characterise Er complexes formed in FZ silicon by the implantation of erbium together with either oxygen or fluorine. The samples have a 2 μm thick layer containing 1019 Er/cm3 alone or in addition 3×1019 O/cm3, 1020 O/cm3 or 1020 F/cm3. Various post-implantation anneals were carried out. Several different erbium centres, which have either C1h monoclinic or trigonal symmetry, are observed and the way in which the type of centre depends on the implantation and annealing conditions is reported. 相似文献
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K. I. Rusakov A. A. Gladyshchuk Yu. P. Rakovich J. F. Donegan S. A. Filonovich M. J. M. Gomes D. V. Talapin A. L. Rogach A. Eychmüller 《Optics and Spectroscopy》2003,94(6):859-863
Efficient photoluminescence (PL) up-conversion in CdSe/ZnS quantum dots prepared by an organometallic approach is reported. It is demonstrated that the efficiency of photon energy up-conversion and the magnitude of the spectral shift can be controlled by (i) the thickness of the ZnS layers, (ii) the temperature dependence of the excited-state absorption coefficient, and (iii) the dependence on the excitation intensity. From the analysis of the experimental data, it is proposed that intrinsic gap states are involved as intermediate states in the PL up-conversion, rather than nonlinear two-photon absorption or Auger processes. 相似文献
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Clauwaert KM Van Bocxlaer JF Major HJ Claereboudt JA Lambert WE Van den Eeckhout EM Van Peteghem CH De Leenheer AP 《Rapid communications in mass spectrometry : RCM》1999,13(14):1540-1545
This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd. 相似文献