共查询到10条相似文献,搜索用时 140 毫秒
1.
A. A. Abd El Raheem A. S. Moustafa Abdel-Aziz Amin 《Fresenius' Journal of Analytical Chemistry》1960,175(1):19-29
Summary Omega Chrome Green BLL was used as a metal indicator for the direct complexometric titration of copper, lead, thorium and for the back titration of aluminium using thorium as a back titrant. It was also used as a colorimetric reagent for the microdetermination of copper and vanadium. A large number of anions and cations do not interfere in such a determination even if they are present in 10 folds the amount of copper or vanadium. Interference due to ferric iron is simply eliminated by the addition of few crystals of ascorbic acid to reduce it to the ferrous state. 相似文献
2.
A. A. Abd El Raheem Abdel Aziz Amin A. S. Moustafa 《Fresenius' Journal of Analytical Chemistry》1960,172(5):347-356
Summary Omega Chrome Fast Blue 2G has been found to be a suitable indicator for the detection of the equivalence point of calcium, magnesium and manganese in the presence of cadmium, nickel, and aluminium, when they are masked by the addition of cyanide or triethanolamine. It is also a suitable indicator for the back titration of aluminium using calcium or magnesium as a back titrant.This dye has also been found to be a suitable reagent for the colorimetric determination of calcium, magnesium, manganese and thorium. 相似文献
3.
A new type of automatic recording titrator has been developed. The titrant is added intermittently and the titration curve is recorded stepwise, potential changes being registered in the intervals between deliveries of titrant. The increments of titrant and the intervals can be pre-set, but give the best results if controlled automatically during the titration. The end-point and the volume of titrant consumed are read from the recorded titration curve. 相似文献
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A cell has been designed for the high-precision coulometric titration, with externally generated titrant, of materials which otherwise undergo undesirable reactions at the working electrodes. With this cell potassium dichromate has been titrated, via its hydrolysis reaction, with hydroxyl ion generated at the cathode, cathodic reduction of the chromium(VI) being circumvented. In this cell 99.9% of the titrant required is generated in one chamber and transferred to another for reaction; the titration is then completed with titrant generated at a second, drip-type electrode working at much lower current. By means of commercially available Leeds and Northrup coulometric titration electrical equipment, titration of NBS 136b Potassium Dichromate gave a purity of 99.976%, standard deviation 0.005%, and of NBS 84d Potassium Acid Phthalate (done as a check) 99.991%, standard deviation 0.005%, both values being in excellent agreement with other work. 相似文献
7.
Sulphuric acid in process effluent streams from an electrorefining copper plant was analysed with a sequential injection (SI) titration system using sodium hydroxide as titrant. In the proposed SI titration system a base titrant, acid analyte and base titrant zone were injected sequentially into a distilled water carrier stream in a holding coil and swept by flow reversal through a reaction coil to the detector. The base zones contained bromothymol blue as indicator and the endpoint was monitored spectrophotometrically at 620 nm. The influence of carrier stream flow rate, acid and base zone volumes and titrant concentration on the linear range of the method was studied to obtain an optimum. A linear relationship between peak width and logarithm of the acid concentration was obtained in the range 0.006-0.178 mol l(-1) of H(2)SO(4) for a NaOH concentration of 0.002 mol l(-1). The results obtained for the SI titration of process samples were in good agreement with a standard potentiometric method with an RSD<0.75% and a sample frequency of 23 samples h(-1). 相似文献
8.
A potentiometric titration method for the direct determination of anionic polyelectrolytes using a plasticized poly(vinyl
chloride) membrane electrode is described. A cationic surfactant solution is used as titrant. The method is based on ion association
between the anionic polyelectrolyte in the sample and the cationic surfactant in the titrant. The end-point is detected as
a sharp potential change due to an increase in the concentration of the free cationic surfactant at the equivalence point.
The sharpness of the titration curve at the end-point is compared for several cationic surfactants; a solution of stearyltrimethylammonium
ion has been found to be superior.
Received: 8 October 1996 / Revised: 17 December 1996 / Accepted: 18 December 1996 相似文献
9.
A potentiometric titration method for the direct determination of anionic polyelectrolytes using a plasticized poly(vinyl
chloride) membrane electrode is described. A cationic surfactant solution is used as titrant. The method is based on ion association
between the anionic polyelectrolyte in the sample and the cationic surfactant in the titrant. The end-point is detected as
a sharp potential change due to an increase in the concentration of the free cationic surfactant at the equivalence point.
The sharpness of the titration curve at the end-point is compared for several cationic surfactants; a solution of stearyltrimethylammonium
ion has been found to be superior.
Received: 8 October 1996 / Revised: 17 December 1996 / Accepted: 18 December 1996 相似文献
10.
Isothermal titration calorimeters have been developed and in use since the 1960s and the number of applications based on empirical rules to use them steadily increases. In this paper a rigorous study of the physical interpretation of the titration heat and the thermodynamic framework underlying isothermal titration calorimetry are proposed. For infinitesimal titrations, the titration heat is independent of the cell type employed, and the interpretation of the titration heat depends on the titrant composition and on the experiment type. Moreover, for the study of the interaction between two solutes in solution, only a combination of two experiments is necessary, and the result is interpreted as the partial enthalpy of interaction at infinite dilution of the solute contained in the titrant solution. 相似文献