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RISS 인기검색어
- 검색키워드
- 발행기관 : Plenum Press ; Springer (검색결과 3 건)
- 무료
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Kamruzzaman, Mohammad,Alam, Al-Mahmnur,Kim, Kyung Min,Lee, Sang Hak,Kim, Young Ho,Kim, Sung Hong Plenum Press ; Springer 2012 Journal of fluorescence Vol.22 No.3
<P>A simple and sensitive chemiluminescence (CL) method coupled with flow-injection technique is proposed to determine naproxen (NAP). The method is based upon the enhancement of the weak CL signal arising from the reaction of Ce(IV) and Na(2)S(2)O(4) with Eu(3+) to form the Eu(3+)-Ce(IV)-Na(2)S(2)O(4) system. The CL intensity was significantly increased by the introduction of NAP into this system in the presence of silver nanoparticles (Ag NPs). Examination of the recorded UV-vis spectra and fluorescence spectra indicated that the energy of the intermediate SO(2)*, which originated from the redox reaction of Ce(IV) and Na(2)S(2)O(4), was transferred to Eu(3+) via NAP and that the process was accelerated by Ag NPs due to their catalytic activity. Under the optimum conditions, the CL intensity was increased with increasing NAP concentration and the correlation was linear (r = 0.9992) over the NAP concentration range of 1-420 ng mL(-1). The limit of detection (LOD) was 0.11 ng mL(-1) with a relative standard deviation (RSD) of 1.15% for 5 replicate determinations of 200 ng mL(-1) NAP. The method was successfully applied to determine NAP in pharmaceutical and biological samples.</P>
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Khan, Muhammad Naeem,Shah, Jasmin,Jan, Muhammad Rasul,Lee, Sang Hak Plenum Press ; Springer 2013 Journal of fluorescence Vol.23 No.1
<P>A simple, sensitive, and accurate spectrofluorimetric method was developed for the determination of citalopram in bulk and pharmaceutical preparations. The method is based on the enhancement of the weak fluorescence signal (FL) of the Tb (III)-citalopram system in the presence of silver nanoparticles. Fluorescence intensities were measured at 555 nm after excitation at 281 nm. Prepared silver nanoparticles (AgNPs) were characterized by UV-Visible spectra and transmission electron microscopy (TEM). Various factors affecting the formation of citalopram-Tb (III)-AgNPs complexes were studied and optimized. The fluorescence intensity versus concentration plot was linear over the range 0.02-14 μg mL(-1), with an excellent correlation coefficient of 0.9978. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 7.15 10(-6) μg mL(-1) and 2.38 10(-5) μg mL(-1) respectively. The proposed method was found to have good reproducibility with a relative standard deviation of 3.66% (n = 6). The interference effects of common excipients found in pharmaceutical preparations were studied. The developed method was validated statistically by performing recoveries studies and successfully applied for the assay of citalopram in bulk powder and pharmaceutical preparations. Percent recoveries were found to range from 98.98% to 100.97% for bulk powder and from 96.57% to 101.77% for pharmaceutical preparations.</P>
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Fluorescence characteristics of isolated dye molecules within silicalite-1 channels.
Shim, Tae Kyu,Lee, Myoung Hee,Kim, Doseok,Kim, Hyun Sung,Yoon, Kyung Byung Plenum Press ; Springer 2012 JOURNAL OF FLUORESCENCE Vol.22 No.6
<P>Fluorescence characteristics of hemicyanine dye molecules isolated from neighboring molecules and strongly restricted inside nanosized pores of zeolite (silicalite-1) crystal were investigated. For samples in which the molecules were sufficiently far away from the others, the fluorescence decay lifetime of the molecules was about 2.2 ns. As the intermolecular distance was reduced, the steady-state fluorescence peak shifted toward the longer wavelength and the fluorescence efficiency decreased markedly. The fluorescence decay lifetime also decreased to 0.8 ns for a sample with the smallest intermolecular distance of 2.1 nm. These results were explained in terms of a dipole-dipole interaction between pairs of dye molecules. From the relation between the intermolecular distances and the fluorescence decay lifetimes of the molecules, the radius of energy transfer of hemicyanine donor-acceptor pair in zeolite matrix was determined to be 2.2 nm, in fair agreement with the calculated F?rster radius between dye molecules of the same species.</P>
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