David C. Locke

Pore structure and surface chemistry of adsorbents obtained by pyrolysis of sewage sludge-derived fertilizer

Abstract Terrene®, a fertilizer product derived from New York City municipal sewage sludge, was pyrolyzed at various temperatures between 400 and 950°C. The pore structure and surface chemistry of the adsorbent materials obtained were characterized using nitrogen adsorption, thermal analysis, potentiometric titration and FTIR. The adsorbents contain a high percentage of inorganic matter (up to 70%) and only up to 30% carbon. The results show that microporosity is developed within the carbon deposit and at the organic/inorganic interface with increasing temperature of heat treatment. An increase in the pyrolysis temperature also results in significant changes in the surface chemistry towards the development of basic nitrogen centers. In particular there was an increase in the pH values of adsorbents’ surfaces from 7 to 11.

Synthetic Fibers as Indicators of Municipal Sewage Sludge, Sludge Products, and Sewage Treatment Plant Effluents

Because of concerns regarding health, safety, and aesthetics, a test that identifies the presence of sewage sludge or its products (biosolids) in commercial materials such as soil conditioners and composts would be useful. This test could also trace the effluent plume from a sewage treatment plant. We have discovered that synthetic fibers serve as such an indicator. Synthetic fibers are abundant in sludge, sludge products, and sewage treatment plant effluents. The fibers evidently are introduced from clothes-washing machines and survive the sewage treatment process. Synthetic fibers were identified using polarized light microscopy, which provided a simple, rapid method for determining the presence or absence of municipal sewage sludge or its products. False positives or false negatives have not occurred with any of the materials examined so far. We also monitored synthetic fibers in surface sediments of Huntington Harbor, Long Island, NY, a harbor receiving the effluent from a trickling filter sewage treatment plant. Fibers generally decrease in size and abundance with distance from the source. In Oyster Bay Harbor, Long Island, an advanced sewage treatment plant is operated with a final microfiltration step. Synthetic fibers are less abundant in the sediments of this harbor.

Enantiomeric separation of the novel growth hormone secretagogue MK-0677 by capillary zone electrophoresis

Abstract MK-0677 {(R)-2-amino-N-[2-(1,2-dihydro-1-(methylsulfonyl) [3H-indole-3,4′-piperidin]-1′yl]-2-oxo-1-[(phenylmethoxy)methyl]ethyl-2-methylpropanamide-monomethane sulfonate} is a novel orally-active growth hormone secretagogue. The R- and S-enantiomers were separated by capillary zone electrophoresis (CZE) using β-cyclodextrin (β-CD) as the chiral selector in a phosphate buffer containing l -tartaric acid and ethanol. Resolution of the enantiomers requires optimizing the buffer constituent concentrations, apparent pH (pHapp) and temperature, T. The presence of an ion-pairing reagent such as tartaric acid is essential to achieve separation. The log of the separation factor, ln α, increases linearly with 1/T over the range from 10°C to 45°C. It is shown that the equilibrium 1:1 CD–enantiomer complex model of Wren and Rowe is a limiting case of the multiple equilibria model of Rawjee and Vigh. An analytical method for MK-0677 based on the CZE separation of it from its S-enantiomeric impurity was validated in terms of limit of detection, limit of quantitation, UV detector linearity, precision, accuracy and ruggedness. The best working conditions include a background electrolyte containing 40 mM l -tartaric acid, 24 mM NaH2PO4, 30 mM β-CD and 25% (v/v) ethanol at pHapp 4.2; a UV detector at 200 nm; and a 52 cm effective length×76 μm I.D. fused-silica capillary operated at 25°C.

Nonionic surfactants for improving resolution of the priority pollutant phenols by micelle-modified capillary electrophoresis

Abstract Nonionic surfactants used as buffer additives in capillary electrophoresis improve the separation of the eleven US EPA priority pollutant phenols. A borate/phosphate buffer (pH 9.8) containing 05–2% (w/v) Tween 40 or Brij 35 surfactant gives better separation of the phenols than the same buffer with no surfactant, especially for the solution pairs 2,4-dichlorophenol/2-methyl-4,6-dinitrophenol; 2-chlorophenol/2,4-dinitrophenol; and 4-nitrophenol/2-nitrophenol. Pentachlorophenol behaves anomalously with increasing concentration of surfactant in the 0 to 0.5% range. Its net mobility is sharply reduced, and peak shape changes from the typically narrow and symmetrical CE peak to a broad, electrophoretically tailing band at a surfactant concentration near the critical micelle concentration (CMC), and then reverts to normal shape at concentrations above the CMC. Compared with CE with buffer only, the small concentrations of surfactant required to produce significant changes in selectivity have little effect on the magnitude of the electroosmotic flow or the runtime. Nonionic surfactants neither increase conductivity nor contribute to Joule heating.

Separation of ergot alkaloids by micellar electrokinetic capillary chromatography using cationic Gemini surfactants

Abstract A micellar electrokinetic capillary chromatographic method using novel cationic dimeric (Gemini) surfactants has been developed for the separation, in less than 8 min, of 17 dihydroergotoxines, aci-alkaloids and oxidation products. Both 1,3-bis(dodecyl-N,N-dimethyl ammonium)-2-propanol (20 mM) and 1,3-bis(tetradecyl-N,N-dimethyl ammonium)-2-propanol (40 mM) surfactants in 50 mM phosphate buffer, pH 3.0, at 20°C produced separations that could not be achieved using single chain tetradecyl- or hexadecyl-trimethyl ammonium micelles. The retention factors (k′) increased linearly with surfactant concentration in accordance with theory. Similarly, the net mobilities generally decreased nonlinearly with surfactant concentration. The smallest alkaloids, i.e. the 6-methylergoline-8-carboxylic acids, and the more polar aci-alkaloids with a Z-type conformation, have the smallest k′ values. For the larger alkaloids, the k′ values with the Gemini surfactants were smaller than with the single chain species, possibly because the more rigid dimeric molecules hinder the partitioning of the alkaloids into the micelle as well as the greater hydrophilicity of the hydroxylated micelles. Increasing buffer pH mainly affects the more strongly acidic and basic alkaloids, causing a marked increase and decrease in net mobilities, respectively. k′ values generally increased with phosphate buffer concentration because of the decreasing solubility of the hydrophobic alkaloids with increasing ionic strength.

Antibiotic properties of porcupine quills.

Porcupine quills possess antibiotic properties. The antibiotic activity is associated with free fatty acids (but not neutral lipids) coating the quills. Extracts of quill fatty acids strongly inhibited the growth of six grampositive bacterial strains. No growth inhibition was observed against four gram-negative strains. Free fatty acids made up 18.6% of total quill lipids in samples collected in the summer, and 5.5% of total lipid in samples collected in the winter. The fatty acids were separated and identified (as the methyl esters) by gas-liquid chromatography and mass spectroscopy. Major components of a complex mixture included 14-methylpentadecanoic, 9-hexadecenoic, hexadecanoic, and 9-octadecenoic acids. It is suggested that porcupines benefit from the quill fatty acids: evidence from healed fractures of major skeletal components (35.1% incidence in 37 skeletons examined) suggests that porcupines fall relatively frequently from trees. Quill antibiotics may limit self-injury suffered in such falls.

Warning Odor of the North American Porcupine(Erethizon dorsatum)

Volatile compounds in the lipid coating of the lower-back quills of the North American porcupine,Erethizon dorsatum, were collected using headspace trapping on Tenax and analyzed by gas chromatography–mass spectrometry (GC-MS), GC with organoleptic detection, and GC with a chiral stationary phase. Over 50 components were isolated, primarily oxygenated aliphatics, lactones, and isoprenoids. The most abundant constituent was tetradecyl acetate, which does not contribute significantly to the odor of the quill lipids. GC with a wide-bore capillary column and a human nose as detector was used to determine the retention time of the peak with the characteristic porcupine odor. Comparison of this organoleptic chromatogram with those obtained with a flame ionization detector and GC-MS showed the compound to be a δ-decalactone. The racemic mixture of this optically active substance does not possess the unique odor. Resolution of the enantiomers of δ-decalactone by GC with a chiral cyclodextrin phase shows that the isomer possessing the characteristic porcupine odor is the(R)-δ-decalactone. We suggest the biological function of this compound is to serve as a warning odor, which, in conjunction with an initial quill strike, produces a conditioned aversion in potential predators.

Separation of the eleven priority pollutant phenols by capillary zone electrophoresis

Capillary zone electrophoresis (CZE) provides highly efficient separation of the eleven US EPA priority pollutant phenols. All of these phenols are completely resolved in fewer than 15 min in a 100 cm x 75 microns I.D. uncoated fused-silica capillary at 22.5 kV using a pH 9.8 phosphate-borate buffer. Buffer pH is the most critical parameter controlling resolution and separation time. A simple theoretical treatment greatly simplifies the pH optimization procedure. The effects on the separation of buffer concentration, applied voltage, and sample quantity injected were studied. Good calibration data were obtained for phenol concentrations up to 50 mg/l. Limits of detection for all phenols were less than 1 ppm.

A Universal Photoionization Dgpector for Liquid Chromatography

Abstract A new liquid chromatography detector has been developed with sensitivity to most organic compounds in the 10 – 100 picogram region, but insensitive to common eluents. Photons from a vacuum UV lamp ionize solutes in the vaporized LC column effluent, without ionizing the mobile phase. Initial studies of its performance and applications indicate considerable promise as a sensitive, universal detector.

Environmental chemical impact of recycled plastic timbers used in the Tiffany Street Pier, South Bronx, New York

An assessment was made of the chemical environmental impact of a new pier constructed of recycled postconsumer waste plastic in the East River, New York City. The waste plastic consists principally of polyethylene and polyethylene terephthalate. Plastic pilings are immune to the marine boring organisms that are destroying conventional wood structures. A variety of organic compounds and metal ions are leached from the plastic surface but in small quantities to produce river water concentrations far lower than those of compounds found to be already present. Many of the leached compounds seem to be characteristic of product residues in the plastic containers. In comparison, significant amounts of As, Cr, Cu, Mn and Se were leached from pressure-treated lumber, another material used in pier construction. In addition to its aesthetic and functional qualities, recycled plastic timber has the significant environmental advantage that it will not add appreciably to the pollutant load of the East River.