RESUMO
The sulfonated analog (TPPTZ-S) of 2,4,6-tris[2'-(4'-phenylpyridyl)]-s-triazine has been synthesized and its analytical utility investigated. The characteristics of the iron(II) complex of this ligand, including optimum conditions of formation, adherence to Beer's law and relative stability are described. Procedures for the quantitative determination of trace amounts of iron with TPPTZ-S are given. The analytical applicability of the reagent is illustrated by the successful determination of iron in E. coli and various beverage and beer samples.
RESUMO
A specimen of 4-aminopyridine purified by repeated sublimation in an atmosphere of nitrogen has been titrated coulometrically in two ways: (1) directly, using the hydrazine-platinum anode, and (2) with perchloric acid, the titration being completed coulometrically and the perchloric acid being standardized coulometrically. The values for the faraday calculated from these titrations are 96,486.40 (1.53) and 96,486.78 (0.57), 1972 NBS coulombs per mole, respectively, the average being 96,486.69 (0.81) and the numbers in the parentheses the standard deviations. The maximum error obtained by combining the estimated maximum errors in the various measurements was 8.4 ppm.
RESUMO
Freezing curves of highly-purified 4-aminopyridine have been obtained with an instrument of new design employing a gold crucible, a platinum resistance thermometer, electrical heating elements on crucible and heat shield, and accessory electrical control devices such that the temperature difference between crucible and shield could be maintained constant within 0.005 degrees while the temperature of the 4-aminopyridine and crucible dropped through the freezing range. No stirring was used. Methods were devised for handling the data as the derivative of temperature with respect to time and of correcting the freezing curve for the heat capacity of the crucible and charge. Although interpretation of the freezing curves obtained on the 4-aminopyridine was confused by attack on the gold by the molten 4-aminopyridine, the initial impurity in the 4-aminopyridine was probably less than the detection limit, 0.001 mole %.
RESUMO
The anodic generation of hydrogen ion on bright platinum in 1.0M sodium perchlorate is not quantitative owing to the formation of a chemical species With oxidizing properties, presumably a peroxydiperchlorate, but 100% current efficiency can be obtained in the anodic generation of hydrogen in 0.25M sodium hydrazinium sulphate, Na(N(2)H(5))SO(4). Five hydrogen ions are formed for each four electrons passed. The efficiency of this "hydrazine-platinum anode" has been demonstrated by the high-precision coulometric titration of tris(hydroxymethyl)aminomethane.
RESUMO
A dipotassium pentacalcium dicalcein salt ("Statocalcein") is recommended for use in place of Calcein as an indicator for fluorimetric titration of calcium with EDTA. The new indicator remains stable in solution for long periods (at least 210 days).
RESUMO
A mixture of equal volumes of perchloric acid and phosphoric acid is an excellent solvent for sulphide ores preliminary to the determination of copper. The dissolution is rapid, no bumping occurs, and the visual adjustment of pH prior to the iodometric determination of copper is easier.
RESUMO
Eleven pyrido and pyridyl derivatives of phenazine (6) and quinoxaline (5) have been examined as chromogens of the ferroin type for iron(II) and copper(I). Three of the quinoxaline derivatives show promise as reagents for iron(II) but are expensive and difficult to prepare.
