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141.
An optical CO2 sensor based on the overlay of the CO2 induced absorbance change of pH indicator dye α-naphtholphthalein in poly(isobutyl methacrylate) (polyIBM) layer with the fluorescence of tetraphenylporphyrin (TPP) in polystyrene layer is developed. The observed luminescence intensity from TPP at 655 nm increased with increasing the CO2 concentration. The ratio I100/I0 value of the sensing film consisting of α-naphtholphthalein in polyIBM and TPP in polystyrene layer, where I0 and I100 represent the detected luminescence intensities from a layer exposed to argon and CO2 saturated conditions, respectively, that the sensitivity of the sensor, is estimated to be 192. The response and recovery times of the sensing film are less than 6.0 s for switching from argon to CO2, and for switching from CO2 to argon. The signal changes are fully reversible and no hysterisis is observed during the measurements. The highly sensitive optical CO2 sensor based on fluorescence intensity changes of TPP due to the absorption change of α-naphtholphthalein in polyIBM layer with CO2 is achieved. 相似文献
142.
催化褪色光度法测定微量锰(Ⅱ)的研究 总被引:6,自引:2,他引:6
本文研究在硫酸介质中,锰(Ⅱ)催化EDTA还原重铬酸银,而使之褪色的新指示反应。确定了催化褪色反应动力学条件,锰(Ⅱ)的浓度在0-0.4μg/ml范围内,工作曲线呈良好的线性关系,检测限为0.011μg/mL,该方法用于天然水及污水中锰的测定,获得满意结果。 相似文献
143.
提出了同时测定铜基合金中铝和铁的流动注射分析法。以0.04mol/LHCl作载液,铬天青S为显色剂,通过测定628nm处铝、铁两配合物的吸光度之和及铝配合物的吸光度,实现了两组分的同时测定。在优化的实验条件下,检测限:Al和Fe分别为1.69×10-3和1.73×10-3mg/L,Al浓度在0~0.8mg/L;Fe浓度在0~1.0mg/L时服从比耳定律。进样频率为60样/h,所拟方法用于实际样品分析,获得满意结果。 相似文献
144.
采用火焰原子吸收分光光度法测定5种英平诸痹灵药酒中钴、锶、锂的含量。结果表明,该类药酒中微量元素Sr含量较高,微量元素Co、Li含量较低,该结果为讨论抗类风湿药物中微量元素与治疗类风湿疾病的关系提供了有用数据。 相似文献
145.
A selective Spectrophotometric method has been developed for the trace determination of copper after adsorption of its 1-phenyl-4,4,6-trimethyl(1H, 4H)-pyrimidine-2-thiol (PTPT) complex onto microcrystalline naphthalene. The complex is quantitatively adsorbed on naphthalene in the pH range 7.5–11.5, separated by filtration, dissolved in dimethylformamide (DMF) and determined spectrophotometrically at 400 nm. Beer's law is obeyed in the concentration range 2.5–37.5 g of copper in 10 ml of DMF. The molar absorptivity and Sandell's sensitivity are 1.30 × 1041 · mol–1 · cm–1 and 0.0048g cm–2, respectively. Ten replicate analyses of a solution containing 20.0 g of copper gave a mean absorbance of 0.410 with a relative standard deviation of 0.91 %. The interferences of various ions have been studied and the method has been validated by the determination of copper in various standard reference materials, beers, wines, human hair, goat liver and environmental samples.On leave from St. Stephen's College, Delhi 110 007, India 相似文献
146.
F. A. L. van der Horst M. H. Post J. J. M. Holthuis U. A. Th. Brinkman 《Chromatographia》1989,28(5-6):267-273
Summary Micellar phase-transfer catalysis (MPTC) offers the opportunity to derivatize carboxylic acids directly in an aqueous matrix without prior extraction of the acids into a suitable aprotic solvent. The currently developed MPTC system consists of a non-ionic surfactant, Arkopal N-130, an ion-pair agent, tetrakis-(decyl)-ammonium bromide, and a novel fluorescence reagent, 9-bromomethylacridine. The MPTC system can be applied to the derivatization of many types of carboxylic acids. The reaction rate is affected by the lipophilicity of the acid and by the presence of other functional groups. For lipophilic carboxylic acids the reaction is complete within 5 min at 60°C and pH 7.0. 相似文献
147.
Subir Ghorai 《Tetrahedron letters》2004,45(32):6191-6194
The first examples of anthracene capped chiral dendrimers derived from a 1,3,5-trisubstituted aromatic core and carbohydrate units in the interior and periphery are described. Excimer formation was evident from the fluorescence spectrum, and both fluorescence and chiroptical properties indicated that the dendrimer does not undergo aggregation in the ground state. 相似文献
148.
F. Buiarelli F. Coccioli R. Jasionowska M. Merolle A. Terracciano 《Chromatographia》2006,64(7-8):475-481
Resveratrol (3,5,4′-trihydroxystilbene) is a phytoalexin that belongs to the group of stilbenes, known to occur in grapes and consequently in grape products. Its presence in wine is an important qualitative parameter because of the several beneficial effects on human health. The aim of this work is the development of a high-performance liquid chromatographic (HPLC) method for the determination of trans resveratrol in wines, and comparisons between the results obtained by different detection techniques: UV-vis spectroscopy, fluorescence spectroscopy and mass spectrometry. Resveratrol is analysed on a C-18 column using gradient elution. The method permits direct injection of sample, revealing to be time-saving, overcoming the need of sample pre-treatment steps. Detection limits were 154.8 ng mL−1 by HPLC-UV, 118.0 ng mL−1 by HPLC-FL and 48.0 ng mL−1 by HPLC-MS. Trans resveratrol has been then quantified in a group of 52 wines derived from different Italian regions, cultivars and winemaking technologies by HPLC-UV. 相似文献
149.
本实验测定了二苄基马来酸酯甲醇溶液的荧光光谱,并发现马来酸酐对该荧光体系有猝灭作用,通过对不同马来酸酐浓度与各种浓度的二苄基马来酸酯甲醇溶液在400nm处荧光强度数据的分析,发现马来酸酐的浓度与荧光猝灭程度在一定范围内呈良好的线型关系。据此,提出了用荧光猝灭法对马来酸酐及二苄基马来酸酯的定量分析 相似文献
150.
A simple, sensitive and rapid derivative spectrophotometric method using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) has been developed for simultaneous determination of Co(II), Ni(II) and Fe(II) which have very similar chemical behavior and appear together in many real samples. The complexes of all these metal ions with 5-Br-PADAP were formed immediately at pH 7.0 ammonium acetate buffered solution and were stable for at least 24 h. Second derivative spectra were selected for evaluation, because working wavelength determination was more precise and spectral overlap was less than in the ordinary and first derivative spectra. Three wavelengths at which the complexes exhibit extremum 2D values for Co(II), Ni(II) and Fe(II) were selected as analytical wavelengths, i.e., 640, 600 and 740 nm, respectively. Calibration curves drawn with zero-to-peak values at mentioned wavelengths were linear between 80 and 2000 ng ml−1 for each metal ion. Concentrations of Co(II) and Ni(II) were calculated from the total 2D values and the sum of the linear equations for these three cations at 640 and 600 nm, after Fe(II) assay by making use of the 2D value at 740 nm. Limits of detection (LOD) for Co(II), Ni(II) and Fe(II) were 2.7, 13.9 and 3.0 ng ml−1, respectively. The method has been applied to tool steel and heater resistance wire samples successfully. 相似文献