Donald H. Wilkins

The separation and determination of nickel, chromium, cobalt, iron, titanium, tungsten, molybdenum, niobium and tantalum in a high temperature alloy by anion-exchange

Abstract An anion-exchange method of separating the constituents in high temperature alloys has been devised. Nine elements including titanium, tungsten, molybdenum, niobium and tantalum are determined in an alloy on a single sample weight. Any combination of the elements mentioned above may be determined in steels and high temperature alloys with a simple ion-exchange scheme suitable for routine analysis.

The determination of aluminum, nickel, cobalt, copper, and iron in alnico

Abstract A method has been developed for the determination of the major constituents of Alnico based on an anion exchange separation of the chloride complexes and the subsequent determination of aluminum, nickel, copper, cobalt and iron with EDTA. The method is more convenient than conventional classical methods.

Calcein blue—a new metalfluorechromic indicator for chelatometric titrations

Abstract A new metal fluorechromic indicator is described for the chelatometric titration of metal ions. Calcein Blue (a condensation product of 4-methylumbelliferone, formaldehyde, and iminodiacetic acid) may be used for the chelatometric determination of metal ions which form highly coloured complexes with chelatometric reagents. A procedure based on reaction rates is given for the determination of nickel and chromium in mixtures without prior separations. Calcein Blue serves as an indicator for the direct titration of the alkaline earth elements as the result of the formation of an indicator-reversal complex.

Ethanol-water-hydrochloric acid eluents in anion-exchange separations

Abstract A ternary system of ethanol-water hydrochloric acid has been investigated for the anion-exchange separation of elements which have low adsorption coefficients in aqueous hydrochloric acid solutions. A ternary system is used to express the data from batch distribution coefficients in order to facilitate the prediction of column separation. The anion-exchange separation of manganese from nickel and calcium and the separation of yttrium and scandium has been accomplished.

The determination of oxygen in titanium: Vacuum fusion with a platinum bath

Abstract Oxygen can be determined in titanium accurately by vacuum fusion with a platinum bath. The platinum bath is preferred to an iron bath or dry bath since more samples can be analysed in a bath without interference from gettering and solidification of the bath. The blank from adding iron or tin with the sample is eliminated.

The coulometric determination of sulfur in silicon-iron

Abstract A coulometric method for the determination of sulfur in metallurgical products has been developed which meets the needs of production control of low sultur contents. The method is rapid and more precise than the conventional combustion technique.

The chelometric determination of aluminum, nickel and manganese without prior separation

Summary Hydroxyethylethylenediaminetriacetic acid is used as a selective reagent for the chelometric determination of Al and Ni in the presence of Mn. Mn is subsequently determined in the same solution by means of a direct EDTA titration. The reagent for the first titrations serves as a masking agent during the manganese determination. Methyl Calcein or Methyl Calcein Blue serves as a metalfluorechromic indicator for the determinations.

The determination of titanium with edta

Abstract The determination, of titanium EDTA by means of a back-titration with standard copper has been investigated. The phenomenon of an irreversible color change has been eliminated by the addition of hydrogen peroxide prior to the addition of EDTA and adjustment of pH. It is theorized that peroxide displaces the hydroxyl (or oxygen) ion in the hydroxy-EDTA- titanium complex and thus inhibits precipitation.

Further comments on metalfluorechromic indicators

Abstract The mechanism previously proposed for the behaviour of metalfluorechromic indicators is further discussed, and criticisms of Korbl and Svoboda are answered.

The chelometric determination of chromium, cobalt(iii) and copper with a metalfluorechromic indicator

Abstract Calcein has been applied as a metalfluorechromic indicator for the back titration of relatively large amounts of cobalt(III), chromium(III) and copper(II). The fluorescent end-point is not impaired by the presence of the highly colored EDTA complexes with these ions. Calcein is suitable as an indicator which is not sensitive to oxidation in alkaline solutions.