共查询到20条相似文献,搜索用时 15 毫秒
1.
Qin WW Gong GQ Song YM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2000,56(5):1021-1025
Magdala Red (MR) binding to protein causes a decrease in the fluorescence intensity of MR at 556 nm. Based on this, a new quantitative determination method for proteins is developed. The linear range of this assay is 0.1-4.0 microg ml(-1) of Bovine Serum albumin (BSA). The measurements can be made easily on a common fluorimeter. The reaction between MR and proteins is completed in 1 min, and the fluorescence intensity is stable for at least 2 h. There is little or no interference from amino acids and most metal ions. The proposed method has been applied to the determination of protein in milk powder and soybean milk powder and the results are in agreement with the results by the other methods. 相似文献
2.
A simple, sensitive, selective, fast and inexpensive assay for the determination of diquat is proposed. The method is based on the reduction of the herbicide to a strongly fluorescent monocation radical with sodium dithionite. The initial rate of this reaction is directly proportional to the diquat concentration. The stopped-flow mixing technique was used because the kinetic data can be obtained in only 7 s, meaning that the method can be automated. The calibration graph is linear over the range 5-500 ng ml-1 and the precision (RSD) is close to 1.2%. The applicability of the method was demonstrated by determining the herbicide in different kinds of samples. 相似文献
3.
L. Pe?a A. Gomez-Hens D. Pérez-Bendito 《Fresenius' Journal of Analytical Chemistry》1990,338(7):821-823
Summary A simple, fast method for the determination of carbamazepine in serum is reported for the first time. It is based on the fluorescent reaction of this drug with cerium(IV) in an acid medium. A stopped-flow mixing module coupled to a conventional spectrofluorimeter is used for this purpose. The linear range of the proposed method is 0.04–140 g ml–1 of carbamazepine and the detection limit is 0.01 g ml–1. The within- and between-assay precision data and selectivity results show the method to be adequate for the determination of carbamazepine in serum by including a preliminary extraction step with dichloromethane. Analytical recoveries from different serum samples are reported. 相似文献
4.
A simple, rapid and automatic fluorimetric method for the determination of total ascorbic acid is described. The method makes use of the stopped-flow mixing technique in order to achieve the rapid oxidation of ascorbic acid by dissolved oxygen to dehydroascorbic acid, which then reacts with o-phenylenediamine to form a fluorescent quinoxaline. The initial rate and fluorescence signal of this system are directly proportional to the ascorbic acid concentration. The calibration graph was linear over the range 0.1-30 microg ml(-1) (kinetic method) and 0.25-34 microg ml(-1) (equilibrium method). The precision (% RSD) was close to 0.5%. The method has been used for the determination of ascorbic acid in pharmaceutical formulations, fruit juices, soft drinks and blood serum. 相似文献
5.
The fluorescence of the water-soluble anionic conjugated polymer, poly[lithium 5-methoxy-2-(4-sulfobutoxy)-1,4-phenylenevinylene] (MBL-PPV), is quenched in dilute aqueous solution by cytochrome c, a small, naturally occurring electron-transfer protein. The large value obtained for the Stern-Volmer constant (K(sv) = 3.2 x 10(8) at pH 7.4, and approximately 10(9) in acidic solutions) is attributed to a combination of two factors: (1) facile ET between the luminescent semiconducting polymer and the protein and (2) the Columb attraction between the oppositely charged polyelectrolytes. This system shows significant potential for biosensor applications. 相似文献
6.
在环境监测中微量F~-的分析受到很大的重视.过去采用了分光光度法、离子选择电极法和荧光光度法,前两种方法选择性好,但灵敏度略低;荧光光度法灵敏度较高,可直接测定简单样品中的微量氟.在测定氟的荧光方法中,均是采用荧光熄灭法.此法的特点是灵敏度高,但操作繁琐,很少用于实际样品分析.我们研究了氟的几个新体系,从中筛选出灵敏度高、操作简便的锆-8-羟基喹啉-5-磺酸体系.在水溶液中测定,1μg F~-使体系荧光强度下降68%,与文献报道的体系相比是较高的.本法灵敏度为0.002μgF~-/mL,是测定氟的最灵敏方法之一. 相似文献
7.
8.
Danian Xu D. C. Neckers 《Journal of photochemistry and photobiology. A, Chemistry》1987,40(2-3):361-370
Absorption, emission and excitation spectral data support the thesis that rose bengal forms H-type aggregates in water and polar, protic solvents. 相似文献
9.
It is found that antibiotic ceftriaxone reacts with polyethyleneimine in aqueous solutions, probably, with the formation of a noncovalent molecular complex (complex I). The product of hydrolysis of complex I, when heated in an aqueous solution (product II), quenches the fluorescence of CdSe/CdS/ZnS coreshell- shell quantum dots, probably, because of the formation of free thiol groups. A possibility of ceftriaxone determination in aqueous solutions is demonstrated. The performance characteristics of the procedure using a spectrofluorimeter and a photocamera combined with a UV light-emitting diode are close to each other (cmin = 1 × 10–6 M, RSD = 10%). Na+, Ca2+, glucose, urea, uric acid, erythromycin, ciprofloxacin, and doxycycline produce no analytical signals under the conditions of ceftriaxone determination. 相似文献
10.
Lei Yun 《Analytica chimica acta》2003,485(1):63-72
A novel kinetic chemiluminescent method using the stopped-flow mixing technique has been investigated for the rapid and sensitive determination of citrate and pyruvate. The method is based on a tris(2,2′-bipyridiyl)ruthenium(III) (Ru(bpy)33+) chemiluminescence (CL) reaction. Ru(bpy)33+ was generated in the mixing chamber by oxidising tris(2,2′-bipyridyl)ruthenium(II) with cerium(IV). After selecting the best operating parameters, calibration graphs were obtained over the concentration ranges 0.38-38 μg ml−1 and 8.7-1300 ng ml−1 for citrate and pyruvate, respectively. The limits of detection were 0.1 μg ml−1 for citrate and 0.3 ng ml−1 for pyruvate. Based on the differential rate of the chemiluminescent reaction corresponding to citrate and pyruvate, a very simple kinetic procedure was developed for the simultaneous determination of both compounds. Mixtures of citrate and pyruvate in ratios between 15:1 and 1.5:1 were satisfactorily resolved. The proposed method was successfully applied to the determination of citrate in pharmaceutical formulations, pyruvate in animal blood serum and both compounds in human urine. 相似文献
11.
12.
13.
四氧杂四烯衍生物荧光熄灭法测定微量草酸 总被引:3,自引:0,他引:3
基于草酸对荧光试剂 2 ,2 ,7,7,1 2 ,1 2 ,1 7,1 7 八甲基 2 1 ,2 2 ,2 3,2 4 四氧杂四烯镁 (MgTOE)的荧光熄灭 ,建立了测定微量草酸的荧光分析方法。在pH4.0NaAc HAc缓冲体系中 ,测定的最大激发波长和发射波长分别为 2 4 5nm和2 98nm ,测定草酸浓度的线性范围为 6.1× 1 0 - 6mol/L~ 8.2× 1 0 - 4 mol/L ,检出限为 8 2× 1 0 - 7mol/L。该法已用于人体尿液及菠菜中草酸的含量分析 相似文献
14.
A simple, sensitive and selective method for the determination of bromide in seawater by using a flow injection/stopped-flow detection technique was examined. The detection system was developed for a new kinetic-spectrophotometric determination of bromide in the presence of chloride matrix without any extraction and/or separation. The detection was based on the kinetic effect of bromide on the oxidation of methylene blue (MB) with hydrogen peroxide in a strongly acidic solution. Large amounts of chloride could enhance the sensitivity of the method as an activator. The decolorisation of the blue color of MB was used for the spectrophotometric determination of bromide at 746 nm. A stopped-flow approach was used to improve the sensitivity of the measurement and provide good linearity of the calibration over the range of 0-3.2 μg ml−1 of bromide. The relative standard deviation was 0.74% for the determination of 2.4 μg ml−1 bromide (n = 5). The detection limit (3σ) was 0.1 μg ml−1 with a sampling frequency of 12 h−1. The influence of potential interfering ions was studied. The proposed method was applied to the determination of bromide in seawater samples and provided satisfactory results. 相似文献
15.
A successful method for the detection of electron transfer proteins such as cytochrome c, hemoglobin and myoglobin has been developed based on the fluorescence quenching of semiconductor nanocrystals. High sensitivity and a good linear relationship are obtained. 相似文献
16.
Modified Stern-Volmer equation is obeyed by bovine serum albumin (BSA)-iodide system showing selective quenching of tryptophanyl
fluorescence of BSA. The fraction of accessible protein fluorescence is 0.56 and the effective Stern-Volmer constant is 290
M-1 at pH 7.4 in 0.005 M phosphate buffer at 25°C. Collisional quenching is operative both in the BSA -I−1 system and the model system, tryptophan-I−1. It is supported by the observed relationship between the ratio of quenching rate constants (k
q
) and diffusion coefficients and alsok
q
with bulk viscosity. 相似文献
17.
18.
19.
O. A. Tyutyunnik G. M. Varshal I. Ya. Koshcheeva I. A. Roshchina G. V. Myasoedova N. I. Shcherbinina N. G. Milovzorov T. V. Shumskaya 《Journal of Analytical Chemistry》2000,55(4):350-353
Sorption of osmium(IV, VI) on complexing sorbents POLYORGS XXIV, POLYORGS 32 M, and POLYORGS 32 V and on the PVA-PGMA-PEPA
sorbent from alkaline and hydrochloric acid solutions is studied. It is demonstrated that equilibrium in systems under study
is attained within 40 min for the POLYORGS XXIV sorbent and within 2.5 h for the POLYORGS 32 V sorbent and that the sorbents
exhibit a sufficiently high sorptive capacity with respect to osmium: from 3.4 to 8 mg of Os(VI) in alkaline solutions and
2.2 mg of Os(IV) in acidic solutions. Optimal conditions of analysis of a concentrate on an EDX-771 energy-dispersive X-ray
fluorescence spectrometer are revealed and, on this basis, a sorption-X-ray fluorescence method that provides the determination
of osmium in a wide concentration range with the detection limit down to 10-6% is developed. 相似文献
20.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1994,50(6):1179-1193
A new spectroscopic procedure for the measurement of glucose concentrations is described which is based on substrate induced quenching (SIQ) of an indicator fluorescence. The method exploits a novel photo reaction between thionine and NADH, the latter being generated due to the reduction of NAD+ in an enzymic reaction between glucose dehydrogenase (GDH) and glucose. The observed SIQ data was analysed using an empirical relation. A quenching constant of 1.8×103 (±100) M−1 is obtained for the substrate induced quenching of thionine by glucose. The reported method, which was investigated over the range 0–1000 μM, offers a glucose detection limit of 2.2 μM. Various applications of the proposed scheme are discussed, including its use to construct a fibre optic biosensor for glucose. 相似文献