John A. Dean

Determination of Phosphorus and Sulfur in Fuel Rich Air–Hydrogen Flames

Excitation conditions for the green HPO bands, the uv PO bands, and the violet S(2) bands were explored. A cylindrical glass shield placed around the tip of a Beckman (sprayer) burner provided a simple arrangement to isolate a fuel rich environment of a reversed air-hydrogen flame. Samples were converted to aerosol in a separate nebulization chamber. The HPO band at 5262 A gave a detection limit of 6 microg/ml; the S(2) band, 5 microg/ml. Owing to low flame noise, both detection limits could be improved with interference filters in place of the Beckman small quartz monochromator. The PO bands are emitted best from fuel rich oxygen-acetylene flames with the normal Beckman sprayer burner. The significant aspect of this study lies in the introduction of liquid samples and circumvention of lengthy, and often uncertain, decomposition steps when handling many types of organic and biochemical compounds containing phosphorus and sulfur.

Pulsed anodic stripping voltammetry of zinc, cadmium and lead with a mercury-coated wax-impregnated graphite electrode

Abstract The use of a thin mercury-film wax-impregnated graphite electrode for the simultaneous determination of cadmium, lead and zinc in an acetate buffer by differential pulse anodic stripping voltammetry is described. Optimal instrumental parameters for maximum resolution and sensitivity for simultaneous analysis of these three elements in natural waters are discussed. The interference of copper with the determination of zinc is investigated in detail. An optimal mercury film thickness for this electrode is suggested.

Extraction and gas chromatographic determination of methyl-, ethyl-, and methoxyethylmercury(II) halides☆

The separation, identification, and determination of methyl-, ethyl-, and methoxyethylmercury(II) halides in biological materials were studied. The procedure developed involved a 24-h leach with 1 M sodium iodide, equilibration of the aqueous phase for 2 min with an equal volume of benzene, and then injection of an aliquot of the benzene phase onto a gas Chromatographic column consisting of 5% cyclohexanedimethanol succinate held on Anakrom ABS. Excellent baseline separation of the Chromatographic peaks was obtained. The extraction steps were monitored with RHgX compounds tagged with 203Hg. Partition coefficients are reported for methyl- and ethylmercury(II) chlorides, bromides, and iodides; several overall formation constants of the anionic complexes RHgCln1-n (n=2, 3) were determined. Results are reported for the recovery of methyl- and ethylmercury(II) halides from inoculated rye seed, humic and inorganic sediment, and fish grown in an aquarium.

Gas chromatographic determination of aqueous halides

Abstract Bromide, iodide, and chloride are extracted from aqueous solutions into toluene-alcohol solutions of tetraheptyl-ammonium carbonate. The tetraheptylammonium halides undergo thermal degradation to 1-haloheptanes and triheptylamine. On-column preparation of the haloheptanes is achieved above 150°C. The halocarbons produce gas chromatographic peaks which are used for quantitative analysis of bromide, chloride, and iodide at low ppm levels.

Rapid determination of chromium in natural waters by chemiluminescence with a centrifugal fast analyzer

Abstract The centrifugal fast analyzer was adapted for luminescence measurements by designing an improved transfer disk which mixes solutions more efficiently and by reprogramming the dedicated computer for rapid data acquisition. The modified analyzer system was applied to the chemiluminescent determination of chromium( III) and, after reduction, chromium(VI), by catalysis of the luminol-peroxide reaction in basic medium. From 50 to 600 p.p.b. of chromium in water samples were determined with a relative standard deviation of 1–2%. Sensitivity can be increased if necessary. The method is very rapid—as many as 11 samples can be analyzed in 2.5 s—and only a small sample, 0.3 ml, is required. Since this. method is selective for uncomplexed chromium(III) ions, comparison of results with analyses for total chromium and chromium(VI) by other methods provides information concerning the chromium species present in a sample and the presence or absence of complexing agents.

Applications of the GeMSAEC Centrifugal Photometric Analyzer in Environmental Analysis the Determination Of Phosphate

Abstract The ORNL GeMSAEC Photometric Analyzer is described briefly. The use of a small computer with this instrument, for data acquisition and handling and for automatic printout of the analytical results, is also described. The determination of orthophosphate by the molybdenum-blue procedure has been utilized in a statistical evaluation of the GeMSAEC system, and the results are presented. This study illustrates the considerations that are important in designing procedures for the GeMSAEC type of analyzer, and the advantages that accrue.

Spectrophotometric methods for the determination of osmium-II: Extraction and determination of osmium in situ with 1.5-diphenylcarbohydrazide

Abstract A method has been developed for the spectrophotometric determination of microgram quantities of osmium in uranyl sulphate solutions. The osmium is oxidised to osmium tetroxide, then extracted with chloroform. The extracts are added to an ethanolic solution of 1:5-diphenylcarbohydrazide. A blue-violet coloured reaction product is formed which exhibits maximum absorbancy at 560 mμ. After a period of 2 hr for colour development the molar absorbancy index is about 31,000. Beers law is adhered to over a range of 30 to 100 μg of osmium with a coefficient of variation of about 4%. A study was made of the effects of foreign substances and only chloride and octovalent ruthenium were found to interfere. Both of these interfering ions can be eliminated.

Mass Spectrometric Investigation of Surface Ionization. VI. Desorption of Th+, Np+, and Pu+ from Tungsten Surfaces

The mean residence times of Th+, Np+, and Pu+ on polycrystalline tungsten surfaces have been determined as functions of temperature using the modulated beam technique. The desorption parameters, determined from the relationship 1 / τ = ω0exp(− Ei / kT), are Ionω0(sec−1)Ei(eV)Th+(1.7 ± 1.5) × 10147.83 ± 0.25Np+(6.8 ± 3.8) × 10136.32 ± 0.12Pu+(1.6 ± 0.9) × 10124.99 ± 0.15.

Determination of Traces of Certain Rare Earths in Uranium Compounds by Ion Exchange and Spectrography

An ion exchange separation followed by a spectrographic determination has been developed for certain of the rare earths present in uranium compounds. This method permits the determination of dysprosium, erbium, europium, gadolinium, neodymium, samarium, and ytterbium at concentrations as low as 0.01 to 1 ppm. Hydrofluoric acid solutions of uranium containing the rare earth elements, with yttrium as an internal standard, were passed through a cation exchanger. The negatively charged uranium fluoride complex passed through the column while the rare earths were retained. After the residual uranium was completely removed by eluting with 2.5 M hydrofluoric acid, the resin bed was ignited, and the resulting ash analyzed spectrographically for the individual rare earth elements. Other cations which separate with the rare earths were easily separated, when necessary, by standard, wet chemical, group separations The standard deviation for the method was about 10%.

The nature of the complexes of 2.2'-dihydroxyazo compounds

Abstract The metal complexes of Pontachrome Violet SW, a di-ortho-dihydroxyazo type dye, were studied in an attempt to deduce a reason for the unusual polarographic behavior such as gave rise to the Willard-Dean method for aluminum. Cis-trans isomers, anionic species and azo coordination to the central cation are ruled out. The most likely cause scems to be the rigidity of the complex with the result that the reduction of the complex occurs by a different mechanism then the reduction of the free dye.