M.Román Ceba

A new method for determining the composition and stability constant of complexes of the form ambn

Abstract A new method is reported for determining the composition of complexes of the form A m B n ; it can be used to differentiate mono- and polynuclear complexes. The method is based on that of Holme and Langmyhr. Good results were obtained for several complexes.

A new graphic method for differentiating mononuclear and polynuclear complexes and for determining their stability constants.

A new graphical method is proposed for differentiating mononuclear and polynuclear complexes as well as for determining the stability constant of any complex A(m)B(n). The method is based on the effect of dilution on the degree of dissociation of the complex. The resultant mathematical equation provides a simple graphical calculation which leads to the determination of the stability constant and also the molar absorptivity of the complex.

A new spectrophotometric method for differentiating mononuclear and polynuclear complexes and for determining their extraction constants

A new spectrophotometric method is proposed for differentiating mononuclear and polynuclear complexes as well as for determining the extraction constant K*(e) of any complex A(m)B(n). The method is based on the effect of dilution on the degree of dissociation of the complex. The precision of log K*(e) is +/- 0.03 when the degree of extraction of the metal is between 20 and 60%. The highest values of log K*(e) determinable by this method are 7, 19, 12 and 18 for 1:1, 2:2, 2:1 and 3:1 complexes, respectively.

Spectrophotometric determination of sulphide in water by re-extraction and ligand exchange using chloroform solutions of copper quinolin-8-olate

A method based on the decoloration produced in organic solutions of coloured complexes when they are shaken with aqueous solutions of anions is proposed for the spectrophotometric determination of sulphide using dilute chloroform solutions of copper quinolin-8-olate. The effects of several variables on the decoloration (pH, shaking time, volume ratio, etc.) were established. The method is very sensitive (the apparent molar absorptivity at 410 nm is 2.35 × 104 l mol–1 cm–1) and can be used for determining sulphide in the presence of other sulphur anions. Trace amounts of sulphide in water were determined spectrophotometrically and the results obtained were compared with those obtained using the methylene blue method.

Analytical properties of pyridine-2-aldehyde guanylhydrazone

The modified synthesis and analytical properties of pyridine-2-aldehyde guanylhydrazone are described for the first time. The solubility, spectral char.

Analytical properties of 1,3-cyclohexanedione bisthiosemicarbazone monohydrochloride

The synthesis and analytical properties of 1,3-cyclohexanedione bisthiosemicarbazone monohydrochloride are described for the first time. The solubility, spectral characteristics, pK values and reactions with 40 cations and 13 anions are reported.

Some observations on the use of 1,4-dihydroxyanthraquinone as a fluorometric reagent for traces of lithium

Abstract A new fluorometric method for the determination of lithium based on the formation of a fluorescent species with 1,4-dihydroxyanthraquinone (Quinizarine), in acetone-water (90-10%) medium and 10−3M in NaOH is described. The fluorescent species has two excitation maxima at 560 and 596 nm and one emission maxima at 620 nm. It is stable at least 7 hr and the calibration graph is linear over the range 50–700 ppb Li. The method has a relative error over the average of measurements of 1.62%.

Spectrophotometric determination of trace amounts of iron(III) by extraction of the mixed-ligand iron—fluoride—purpurin complex

The characteristics of the mixed-ligand iron(III)-fluoride-purpurin complex, including optimum conditions of formation and extraction into methyl isobutyl ketone are described. A procedure for determination of trace amounts of iron in fluoride medium (0.5M) with purpurin (1,2,4,-trihydroxy-anthraquinone) in methyl isobutyl ketone is given. The method is suitable for determining iron in the presence of large amounts of aluminium, cyanide, phosphate and nickel.

L, 8-Dihydroxyanthraquin0Ne-Li(I) Reaction. Spectrofluorometric Determination Of Li(I) In An Ethanolic And Acetonic Media

Abstract A spectrofluorometric study of the reaction 1, 8-Didydroxv anthraquinone-Li(I) was made in ethanol and acetone media. A new method for the spectrofluorometric determination of Li(I) is proposed, with a range between 100 and 700 ppb of Li(I) in ethanolic medium and between 50 and 450 ppb in acetone medium. The methods show errors of 2.00 and 2.90 % respectively.

Cyclohexane-1,3-dione bisthiosemicarbazone monohydrochloride as a spectrophotometric reagent for the rapid determination of chlorate in perchloric acid medium

Cyclohexane-1,3-dione bisthiosemicarbazone monohydrochloride produces coloured solutions with chlorate ions in perchloric acid medium, in the presence of chloride ions. The yellow colour obtained (molar absorptivity 1.7 × 104 l mol–1 cm–1 at a wavelength of 402 nm) has been used for the spectrophotometric determination of trace amounts of chlorate. The reaction is of considerable interest, as at present few useful colour reactions are known for the chlorate ion. An important advantage of using this reagent is the stability of the yellow coloured solution obtained.