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Geology topics

C. E. White

Publications and source records attributed to C. E. White.

6 recordsLinked to original sources
USGS2002

Quercetin as colorimetric reagent for determination of zirconium

Methods described in the literature for the determination of zirconium are generally designed for relatively large amounts of this element. A good procedure using colorimetric reagent for the determination of trace amounts is desirable. Quercetin has been found to yield a sensitive color reaction with zirconium suitable for the determination of from 0.1 to 50 of zirconium dioxide. The procedure developed involves the separation of zirconium from interfering elements by precipitation with p-dimethylaminoazophenylarsonic acid prior to its estimation with quercetin. The quercetin reaction is carried out in 0.5N hydrochloric acid solution. Under the operating conditions it is indicated that quercetin forms a 2 to 1 complex with zirconium; however, a 2 to 1 and a 1 to 1 complex can coexist under special conditions. Approximate values for the equilibrium constants of the complexes are K 1 = 0.33 x 10 -5 and K 2 = 1.3 x 10 -9 . Seven Bureau of Standards samples of glass sands and refractories were analyzed with excellent results. The method described should find considerable application in the analysis of minerals and other materials for macro as well as micro amounts of zirconium.

Analytical Chemistry↗
USGS2002

Fluorometric study of the magnesium—Bissalicylidene-ethylenediamine aystem

Magnesium ions combine with bissalicylidene-ethylenediamine in slightly alkaline N,N′-dimethylformamide to form a highly fluorescent complex which serves for the determination of trace amounts of magnesium. The yellow complex fluoresces blue when irradiated with ultraviolet light. The chelate shows maximum fluorescence excitation at 355 mμ and has a fluorescence emission maximum at 439 mμ. A complex having a metal to ligand ratio of 1 to 1 is formed. The method is sensitive to 7 × 10 −6 μmole of magnesium per ml. The analysis of Bureau of Standards samples with the reagent showed excellent correlation between the fluorometric and spectrophotometric procedures

Analytical Chemistry↗
USGS2002

Spectrophotometric study of the magnesium-bissalicylidene-ethylenediamine system

Magnesium reacts with bissali-cylene-ethylenediamine in N,N′-dimethylformamide to yield a yellow complex. A spectrophotometric study was made on the reaction as used for the determination of trace amounts of magnesium. Maximum absorbance was obtained at 355 mμ when the solution contained 0.25 ml. of 0.5M isobutylamine per 25-ml. volume. A complex having a metal to ligand ratio of 1 to 1 is formed. The absorbance obeys Beer's law, and 3.8 × 10 -4 γ of magnesium per ml. can be detected if a 5-cm. light path is used. A value of 13,450 liter mole -1 cm. -1 was obtained for the molar absorptivity. The procedure of analysis is simple and results show a standard deviation of less than 1%

Analytical Chemistry↗
USGS1951

Determination of lithium in rocks: Fluorometric method

The gravimetric method in general use for the determination of lithium is tedious, and the final weighed product often contains other alkali metals. A fluorometric method was developed to shorten the time required for the analysis and to assure that the final determination is for lithium alone. This procedure is based on the complex formed between lithium and 8-hydroxyquinoline. The fluorescence is developed in a slightly alkaline solution of 95% alcohol and measurement is made on a photoelectric fluorometer. Separation from the ore is carried out by the wet method or by the distillation procedure. Sodium and potassium are removed by alcohol and ether, but complete separation is not necessary. Comparison of analyzed samples shows excellent agreement with spectrographic and gravimetric methods. The fluorometric method is more rapid than the gravimetric and produces more conclusive results. Another useful application is in the preparation of standard lithium solutions from reagent quality salts when a known standard is available. In this case no separations are necessary.

Analytical Chemistry↗
USGS1951

Fluorometric determination of zirconium in minerals

The increasing use of zirconium in alloys and in the ceramics industry has created renewed interest in methods for its determination. It is a common constituent of many minerals, but is usually present in very small amounts. Published methods tend to be tedious, time-consuming, and uncertain as to accuracy. A new fluorometric procedure, which overcomes these objections to a large extent, is based on the blue fluorescence given by zirconium and flavonol in sulfuric acid solution. Hafnium is the only element that interferes. The sample is fused with borax glass and sodium carbonate and extracted with water. The residue is dissolved in sulfuric acid, made alkaline with sodium hydroxide to separate aluminum, and filtered. The precipitate is dissolved in sulfuric acid and electrolysed in a Melaven cell to remove iron. Flavonol is then added and the fluorescence intensity is measured with a photo-fluorometer. Analysis of seven standard mineral samples shows excellent results. The method is especially useful for minerals containing less than 0.25% zirconium oxide.

Analytical Chemistry↗