Edwin J. Parks

Characterization by high performance liquid chromatography (HPLC) of the solubilization of phosphorus in iron ore by a fungus

SummaryThe value of iron ore is adversely affected by phosphorus in concentrations over 0.03% by weight. The present research concerns the use of metabolic products of aPenicillium-like fungus to leach insoluble phosphates (hydroxyapatite) from ores. Ion chromatography was used to measure metabolism of glucose into acidic fragments. The rate and products of glucose degradation depended on both the chemical composition of the growth medium (buffered or not) and incubation conditions (shaken or quiescent). The principal products were identified as oxalic acid and isomers of propylene dicarboxylic acid, mainly itaconic acid. Continued, slow metabolism of itaconic acid generates more oxalic acid. Aliphatic acids were not detected. Both iron ore phosphate and calcium phosphate were partially solubilized by either the spent broth or aqueous oxalic acid. Solubilization of ore phosphorus was greatly assisted by hydrochloric acid added to the spent broth in small increments. The data suggest biological alternatives to costly leaching procedures that use only mineral acids.

Application of a graphite furnace atomic absorption detector automatically coupled to a high-performance liquid chromatograph for speciation of metal-containing macromolecules

Abstract High-pressure liquid chromatography (HPLC) coupled with graphite furnace atomic absorption (GFAA) is capable of sensitive, nearly non-destructive, element-specific separation and detection of a wide range of molecular species containing metals or metalloids. Applications of HPLC—GFAA techniques are discussed, including size exclusion chromatography for the analysis of experimental organometallic polymers containing chemically bonded biocidal organotin moieties, and reversed bonded phase chromatography for analysis of novel organotin silicates. In conjunction with variably sensitive optical refractive index/ultra violet absorption detection, GFAA demonstrates separation of the polymers into at least two tin-containing fractions of widely different molecular weight (MW). The relative proportions of high- and low-MW fractions have important implications with respect to performance specifications for these and similar controlled release materials. Tin-specific and silicon-specific analysis of an organotin silicate demonstrates co-elution of species containing each element. Future off/on-line 29Si and 119Sn Fourier transform nuclear magnetic resonance spectroscopy will demonstrate whether each element is bonded to the same molecular species.

Characterization of organotin species using microbore and capillary liquid chromatographic techniques with an epifluorescence microscope as a novel imaging detector

The novel application of a UV epifluorescence microscope as an imaging detector for microbore and capillary high-performance liquid chromatography (HPLC) is reported. The microscope is focused on an in-line quartz flow cell incorporated down stream of a microbore HPLC column or directly on an optically clear portion of fused-silica capillary columns for analyte detection. The effect of different fluorescent ligand to analyte ratios on detection limits is also reported, as well as the effect of different image volume sizes produced by changes in microscope objective lens magnification power. Determination of relative sensitivities an detection limits for methyl- and butyltin compounds, complexed with fluorescent dyes, reveals that the organotins show decreasing sensitivity as the number of alkyl substituents on the tin atom increases, with minimum detectable amounts of 6-160 pg of analyte-ligand complex.

Characterization of organometallic copolymers and copolymerization by size-exclusion chromatography coupled with trace metal- and mass-sensitive detectors

Abstract An important class of controlled-release, biocidal triorganotin-containing copolymers (OMPs) is produced by the free radical initiated reaction of a triorganotin methacrylate (typically tributyltin methacrylate, TBTM) with methyl methacrylate. In earlier studies, we have demonstrated that size-exclusion chromatography (SEC) on μStyragel, coupled with an in-line graphite furnace atomic absorption detector (GFAA) quantifies at least two well-resolved tin-bearing molecular weight fractions observed in many different commercial OMP formulations: a polymer fraction, and, probably, unreacted TBTM. When tetrahydrofuran is used as the eluent, a third component, believed to be an ionic tin-containing compound, is adsorbed and slowly eluted. We now verify that a dilute solution of acetic acid in the tetrahydrofuran efficiently desorbs this species. If a one percent solution of acetic acid in tetrahydrofuran is introduced into the mobile phase as a discrete, injected volume several minutes after the injection of the polymer formulation, there appears in the SEC—GFAA chromatogram: the polymer peak, the monomer peak, several minutes of tailing, and, finally a spike, with little additional tailing. However, when a one percent solution of acetic acid in tetrahydrofuran is used as the eluent, the high polymer peak is substantially reduced in size owing to acid hydrolysis of polymeric esters to which the tributyltin is chemically bonded; the low-molecular-weight peak is substantially increased. Thus, delayed injection of acetic acid serves the purpose of avoiding acid hydrolysis of the polymer. In the work described, only trace amounts of acetic acid (0.5 μl to 5.0 μl) were introduced by injection into the tetrahydrofuran mobile phase, whereas prolonged exposure to dilute solutions of acetic acid in tetrahydrofuran — e.g. , introduced by a gradient method— could be expected to shorten column life. Partial decomposition of esters was found in partially reacted OMPs after one year of storage at −780°C.

Bioleaching of cobalt from smelter wastes byThiobacillus ferrooxidans

SummaryThe bioleaching of cobalt from domestic, industrial smelter wastes was studied.Thiobacillus ferrooxidans solubilized Co from sulfidic dross furnace mattes. At pulp densities of 4% (w/v) up to 600 mg of Co per liter of leaching solution was released from nickel matte, corresponding to removal of about two-thirds of the original amount of Co in the matte. Bioleaching methods may be useful as a component of a process for solubilization and recovery of Co from sulfidic smelter mattes.

Effect of pH on the emission properties of aqueous tris(2,6-dipicolinato)terbium(III) complexes

Modification des proprietes luminescentes du complexe du terbium (III) en fonction de la protonation du coordinat dicarboxylique

Characterization of organometallic polymers by size exclusion chromatography on preconditioned columns

Abstract Tin-bearing organometallic polymers (OMPs) having tributyltin substituents on pendant carboxylic acid groups are in current, extensive use as marine biocides. Fractionation of the substituted polymer by size exclusion chromatography (SEC) on plystyrene cross-linked with divinylbenzene (PS—DVB) is complicated by surface adsorption of cations even on this relatively inert packing material. This paper describes chromatography performed successfully on PS—DVB columns following pretreatment with an organometallic cation to establish a positively charged surface. Tin-specific SEC illustrates the methodology. The column packing is preconditioned with an organic solution of tributyltin-bearing cation dervied from monomer esters, to prevent cleavage of the tin-bearing moieties from the OMP. Mass-sensitive differential refractive index and element-specific graphite furnace atomic absorption spectroscopy detectors in tandem give self-consistent values for key molecular parameters (molecular weight, molecular weight dispersion, and the distribution of tin in high- and low-molecular-weight fractions). Samples prepared on a laboratory scale or on commercial scale show no substantial differences in products prepared by two substantially different reaction pathways. The modified procedure is recommended as a critical method for comparing different organometallic polymers in organic solution.

Effect of Certain Crystalline Substances on Physical Properties of Elastomers I. Stress-Strain behavior

Abstract Crystalline organic compounds containing a β-naphthyl group cause pronounced stiffening of rubber vulcanizates under certain conditions. When these materials are removed by extraction, the reinforcing effect vanishes. Reversibility of this effect indicates that the forces involved are not those associated with primary bonds. Reinforcement by at least one of these materials, PBNA, is obtained with vulcanizates made from various elastomers and vulcanizing agents, and is essentially independent of the state of cure. In some instances about five per cent of PBNA, the most effective of these, produces the same stiffness on first extension as 40 phr carbon black. Any PBNA dissolved in the rubber has no effect on stiffness. Thus, less than three per cent crystalline PBNA may produce an isotropic Youngs modulus of about 20 kg/cm2 at room temperature. At higher concentrations of PBNA, strain continues to decrease but hardness does not change proportionally. The temperature coefficient of Youngs modulus ...

Ethylene Propylene Copolymers: Crystal-Linity, Infrared, and Creep Studies

Abstract Density, infrared, and creep studies have been made of ethylene propylene copolymers containing up to about 50 mole per cent propylene and their homopolymers. The degree of crystallinity (volume fraction of polyethylene crystals), as measured by density and x-ray studies, decreases with increased propylene content. This change is also reflected in the intensity of the 13.7 μ band in the infrared spectra of the polymers. The measured amount of unsaturation (0.1–0.2 per cent) in the copolymers is too small to account for the presence of several infrared bands which are often attributed to unsaturation. An unsaturation of 0.90 per cent was obtained for a terpolymer where the third component was unsaturated. Indentation-creep studies showed the creep to be nearly proportional to the logarithm of time with a slope of 10 per cent creep per decade for 0.1–10 min. Compliance-temperature graphs were found to be quite similar to those for the styrene butadiene rubber SBR 1500.