Volumetric titration of iron (III)-salts with disodium EDTA, using FeII-cacotheline as indicator

Summary A volumetric method has been developed for the determination of iron (III) with disodium EDTA, using a mixture of cacotheline and iron(II) as indicator. The titration of the iron (III) salt is carried out in a buffered solution ofph 4–5 in carbon dioxide atmosphere with magnetic stirring, until a pink color appears. The pink color is due to the reduction of cacotheline by ferrous-EDTA. The reduction occurs only when all the iron (III) is complexed by EDTA. The end point is sharp and the method has been found to give results accurate to±0.3 to±0.5 percent.     

The application of tiron in photometric titrations

Tiron is a suitable titrant for the direct, selective photometric titration of bismuth(III), iron(III) and thorium(IV) in acidic solutions. Metal ions such as lead(II), nickeI(II) and copper(II) do not interfere; this is in contrast with titrations in which EDTA or a similar chelating agent is used as the titrant.     

EDTA titration of bismuth(III) in ores and concentrates with biamperometric indication

Summary A method is described for the chelatometric titration of bismuth(III) with biamperometric indication. It is applied to ores and concentrates and can also be used in presence of interfering elements (as Zr, Tl, In, Mo, Cu, Fe).

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Zusammenfassung Ein Verfahren wird beschrieben zur chelatometrischen Titration von Wismut(III) mit biamperometrischer Endpunktsanzeige. Es wird auf Erze und Konzentrate angewendet und kann auch in Gegenwart störender Elemente (wie Zr, Tl, In, Mo, Cu, Fe) benutzt werden.

     

Determination of cationic polyelectrolytes using a photometric titration with crystal violet as a color indicator

The reaction of the cationic dye, crystal violet (CV) with the anionic polyelectrolytes such as potassium poly (vinyl sulfate) (PVSK) results in a decrease of the absorbance of CV at the maximum absorption wavelength (590 nm). This change of the absorption spectra of the CV has been already applied to the determination of anionic polyelectrolytes using flow injection analysis method. In this paper, CV was applied to the indicator for the determination of cationic polyelectrolytes such as poly (diallyldimethylammonium chloride) (Cat-floc) by photometric titration, using a PVSK solution as a titrant. The end-point of the titration is detected as the break point of the titration curve. A linear relationship between the concentration of cationic polyelectrolyte and the end-point volume of the titrant exists in the concentration range from 0 to 5×10⁻⁵ eq. mol dm⁻³ for Cat-floc, glycol chitosan and methylglycol chitosan. The effects of the concentration of CV and coexisting electrolytes in the sample solution and the effect of pH of the sample solution on the degree of the change of absorbance at the end-point were also examined.     

Reaction of iron(III) with tiron in the presence of ferrozine, and determination of tiron

Tiron is oxidized by iron(III) in the presence of Ferrozine with an apparent four-electron transfer and aromatic ring opening. The apparent molar absorptivity referred to the Tiron in the reaction corresponds to approximately 1.12 x 10(5) l.mole(-1).cm(-1).     

The photometric titration of mercury with trien

A mercury(II) solution containing copper ion can be titrated photometrically at pH 4.7 with triethylenetetramine solution (trien) after the addition of iminodiacetic acid (IDA) ; IDA causes a reversal of the effective formation constants of Hg-trien and Cu-trien and permits the titration. Copper-trien which absorbs at 580 mμ serves as the indicator for the titration. Mercury can be determined in presence of many other metals with an accuracy of about 1%; the main interferences are iron-(III), nickel, bismuth and chloride ion.     

Determination of Fe(II)-Fe(III) and Fe(III)-Ni(II) by the two-component potentiometric complexometric titration

Summary The two-component complexometric potentiometric titration has been applied to the simultaneous determination of Fe(III) and Fe(II), and of Fe(III) and Ni(II) in solution. In each case the two analytes were determined by reading the end-points directly from the titration curve. The end-points are determined in a sense arbitrarily, but they are repeatable and easy to be detected precisely. However, the apparent (found) analytical results are biased. They are effectively corrected with the use of a set of two calibration equations (uncomplete second degree polynomials), which approximate the relationship between found endpoints and true concentrations of analytes in solution. The regression coefficients in the equations are determined on the basis of titration data obtained for standard solutions whose compositions correspond to a 2² factorial. Permanent address: Department of Analytical Chemistry, Jagiellonian University, Krakow     

Photometric titration of titanium(III) with iron(III)

An oxidimetric titration of titanium(III) with iron(III) with a photometric end-point is proposed. Acetylacetone was used to obtain an intensely coloured titanium(III) complex; titanium(III) was formed by prereduction with chromium(II) or vanadium(II). Amounts of titanium down to 35 μg were determined with fairly good accuracy and precision. Few common elements interfere.