@article {2092, title = {Mechanistic Studies on N-Acetylmuramic Acid 6-Phosphate Hydrolase (MurQ): An Etherase Involved in Peptidoglycan Recycling}, journal = {Biochemistry}, volume = {47}, number = {44}, year = {2008}, note = {ISI Document Delivery No.: 366TUTimes Cited: 4Cited Reference Count: 37Hadi, Timin Dahl, Ulrike Mayer, Christoph Tanner, Martin E.}, month = {Nov}, pages = {11547-11558}, type = {Article}, abstract = {Peptidoglycan recycling is a process in which bacteria import cell wall degradation products and incorporate them back into either peptidoglycan biosynthesis or basic metabolic pathways. The enzyme MurQ is an N-acetylmuramic acid 6-phosphate (MurNAc 6-phosphate) hydrolase (or etherase) that hydrolyzes the lactyl side chain from MurNAc 6-phosphate and generates GlcNAc 6-phosphate. This study supports a mechanism involving the syn elimination of lactate to give an alpha,beta-unsaturated aldehyde with (E)-stereochemistry, followed by the syn addition of water to give product. The observation of both a kinetic isotope effect slowing the reaction of [2-H-2]MurNAc 6-phosphate and the incorporation of solvent-derived deuterium into C2 of the product indicates that the C2-H bond is cleaved during catalysis. The observation that the solvent-derived 180 isotope is incorporated into the C3 position of the product, but not the C1 position, provides evidence of the cleavage of the C3-O bond and argues against imine formation. The finding that 3-chloro-3-deoxy-GlcNAc 6-phosphate serves as an alternate substrate is also consistent with an elimination-addition mechanism. Upon extended incubations of MurQ with GlcNAc 6-phosphate, the alpha,beta-unsaturated aldehydic intermediate accumulates in solution, and H-1 NMR analysis indicates it exists as the ring-closed form of the (E)-alkene. A structural model is developed for the Escherichia coli MurQ and is compared to that of the structural homologue glucosamine-6-phosphate synthase. Putative active site acid/base residues are probed by mutagenesis, and Glu83 and Glu114 are found to be crucial for catalysis. The Glu83Ala mutant is essentially inactive as an etherase yet is capable of exchanging the C2 proton of substrate with solvent-derived deuterium. This suggests that Glu83 may function as the acidic residue that protonates the departing lactate.}, keywords = {CATALYSIS, CELL-WALL, COLI GLUCOSAMINE-6-PHOSPHATE SYNTHASE, DERIVATIVES, ELIMINATION, ENOYL-COA HYDRATASE, ENVIRONMENT, ESCHERICHIA-COLI, INHIBITION, PHOSPHATE}, isbn = {0006-2960}, url = {://000260507100019}, author = {Hadi, T. and Dahl, U. and Mayer, C. and Tanner, M. E.} } @article {2220, title = {Nonlinear optical properties of Schiff-Base-containing conductive polymer films electro-deposited in microgravity}, journal = {Advanced Materials}, volume = {20}, number = {12}, year = {2008}, note = {ISI Document Delivery No.: 320XMTimes Cited: 5Cited Reference Count: 41Pietrangelo, Agostino Sih, Bryan C. Boden, Britta N. Wang, Zhenwei Li, Qifeng Chou, Keng C. MacLachlan, Mark J. Wolf, Michael O.}, month = {Jun}, pages = {2280-+}, type = {Article}, abstract = {Organic-inorganic hybrid films prepared from copper(II)-containing Schiff base complexes bearing long alkoxy chains grown under microgravity conditions show enhanced third-order NLO susceptibilities relative to films grown at 1 g.}, keywords = {2ND-ORDER, BOND-LENGTH ALTERNATION, CHAIN, CONJUGATED, COPPER(II), ENVIRONMENT, GENERATION, GRAVITY, HYBRID, PHTHALOCYANINE THIN-FILMS, POLYMERS}, isbn = {0935-9648}, url = {://000257268500006}, author = {Pietrangelo, A. and Sih, B. C. and Boden, B. N. and Wang, Z. W. and Li, Q. F. and Chou, K. C. and MacLachlan, M. J. and Wolf,Michael O.} } @article {918, title = {Arsenic speciation in human urine: are we all the same?}, journal = {Toxicology and Applied Pharmacology}, volume = {198}, number = {3}, year = {2004}, note = {ISI Document Delivery No.: 844GRTimes Cited: 26Cited Reference Count: 34}, month = {Aug}, pages = {297-306}, type = {Review}, abstract = {we studied the arsenic speciation in human urine samples by using high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). We investigated the arsenic speciation in the urine collected from nine volunteers during a 3-day period after a meal of blue mussels, Mytilus edulis. We also studied the effect of cooking on the arsenic speciation. Arsenobetaine and dimethylarsinic acid (DMAA) were the major arsenic metabolites found in the urine samples. Significant amounts of unknown metabolites were also detected. The excretion patterns of arsenic from individuals were generally similar except for two subjects. One of whom excreted high amounts of arsenobetaine even though no arsenic-rich food was eaten for 3 days before the experiment. The results reveal that we need a better understanding of the metabolism of arsenic compounds by human. (C) 2004 Elsevier Inc. All rights reserved.}, keywords = {arsenic, arsenobetaine, arsenosugar, ENVIRONMENT, HPLC, ICP-MS, IDENTIFICATION, INGESTION, LIQUID-CHROMATOGRAPHY, MASS-SPECTROMETRY, METABOLITES, METHYLATED ARSENICALS, mussel, PRODUCTS, TRIVALENT, urine}, isbn = {0041-008X}, url = {://000223146600007}, author = {Lai, V. W. M. and Sun, Y. M. and Ting, E. and Cullen, W. R. and Reimer, K. J.} } @article {877, title = {Arsenic uptake by the Douglas-fir (Pseudotsuga menziesie)}, journal = {Applied Organometallic Chemistry}, volume = {18}, number = {12}, year = {2004}, note = {ISI Document Delivery No.: 880PLTimes Cited: 2Cited Reference Count: 26International Conference on Environmental and Biological Aspects of Main Group OrganometallicsDEC 03-05, 2003Pau, FRANCE}, month = {Dec}, pages = {626-630}, type = {Proceedings Paper}, abstract = {The Douglas fir (Pseudotsuga menziesie) growing in an arsenic-rich gold-bearing region contains elevated arsenic concentrations in new-growth stems (374ppm dry weight (dw)) and needles (257ppm dw). Speciation of methanol-water extracts by using high-performance liquid chromatography- inductively coupled plasma mass spectrometry show that arsenite is the major species in needles but arsenate is more dominant in stems. Only traces of methylarsenicals are present. Arsenic concentrations in other tree species growing in the region are generally much lower; dimethylarsinate was extracted from a spruce cone. Copyright (C) 2004 John Wiley Sons, Ltd.}, keywords = {accumulation, arsenic, CANADA, CONTAMINATED SOILS, Douglas fir, ENVIRONMENT, fern, gold mine, HPLC-ICP-MS, HYPERACCUMULATOR, PHYTOCHELATINS, PLANTS, SPECIATION}, isbn = {0268-2605}, url = {://000225801600005}, author = {Haug, C. M. and Reimer, K. J. and Cullen, W. R.} } @article {677, title = {The analysis of volatile trace compounds in landfill gases, compost heaps and forest air}, journal = {Applied Organometallic Chemistry}, volume = {17}, number = {3}, year = {2003}, note = {ISI Document Delivery No.: 651ZYTimes Cited: 7Cited Reference Count: 28}, month = {Mar}, pages = {154-160}, type = {Article}, abstract = {Landfill gas, cryotrapped on a loop fashioned from a length of a capillary gas chromatography (GC) column, was examined for volatile organometallic compounds (VOMCs) and for volatile organic compounds (VOCs) by using GC-mass spectrometry (MS). A large number of organic components were present and many were identified, but the only VOMCs present in high enough concentrations to be detected were trimethylstibine and tetramethyltin. The use of inductively coupled plasma (ICP)-MS as an element-specific detector allowed the identification of a number of other organometallic species in the landfill gas, including trimethylarsine and trimethylbismuth, and, for the first time, butyltrimethyltin and dibutyldimethyltin. The presence of molybdenum hexacarbonyl was confirmed. Gas from a large-scale compost heap and from compost incubated in the laboratory contained iodomethane but no common VOMCs (GC-ICP-MS). Only VOCs were present in forest air (GC-MS). Copyright (C) 2003 John Wiley Sons, Ltd.}, keywords = {(VOCs), BISMUTH, CHROMATOGRAPHY, EMISSIONS, ENVIRONMENT, GC-ICP-MS, GC-MS, METAL-COMPOUNDS, ORGANIC-COMPOUNDS, organotin speciation, phosphine, SITE, volatile organic compounds, volatile organometallic compounds (VONICs), WASTE}, isbn = {0268-2605}, url = {://000181355200002}, author = {Maillefer, S. and Lehr, C. R. and Cullen, W. R.} } @article {738, title = {Direct determination of polycyclic aromatic hydrocarbons in solid matrices using laser desorption/laser photoionization ion trap mass spectrometry}, journal = {Journal of the American Society for Mass Spectrometry}, volume = {14}, number = {6}, year = {2003}, note = {ISI Document Delivery No.: 684BJTimes Cited: 8Cited Reference Count: 48}, month = {Jun}, pages = {562-570}, type = {Article}, abstract = {The development and characterization of a new instrument for solid sampling which couples IR laser desorption followed by UV laser photo-ionization and analysis using an ion trap mass spectrometer has been investigated. For calibration, a new type of solid sample preparation involving activated charcoal as the solid substrate was used. This solid sample provided a steady signal for several thousand laser shots, which allowed optimization of the experimental procedure. It was found that both the IR and UV intensity and the delay between them play an important role in both the magnitude and type of signals observed. A method of gas phase accumulation with multiple laser shots was examined. Finally, this technique was demonstrated to be effective in providing direct qualitative information. for N.I.S.T. SRM 1944 river sediment sample with no sample pre-treatment. (J Am Soc Mass Spectrom 2003,14,562-570) (C) 2003 American Society for Mass Spectrometry.}, keywords = {CONTAMINATED SOILS, ENVIRONMENT, FLUORESCENCE, GAS-CHROMATOGRAPHY, IONIZATION DETECTION, MULTIPHOTON IONIZATION, ORGANIC-SURFACE ANALYSIS, SIMULATION, SPECTROSCOPY, THERMAL-DESORPTION}, isbn = {1044-0305}, url = {://000183185300002}, author = {Specht, A. A. and Blades, M. W.} } @article {361, title = {Determination of arsenic species in a freshwater crustacean Procambarus clarkii}, journal = {Applied Organometallic Chemistry}, volume = {16}, number = {3}, year = {2002}, note = {ISI Document Delivery No.: 521YCTimes Cited: 14Cited Reference Count: 37}, month = {Mar}, pages = {123-132}, type = {Article}, abstract = {The arsenic species present in samples of the crayfish Procambarus clarkii caught in the area affected by the toxic mine-tailing spill at Aznalcollar (Seville, Southern Spain) were analyzed. The total arsenic contents ranged between 1.2 and 8.5 mug g(-1) dry mass (DM). With regard to the different species of arsenic, the highest concentrations were for inorganic arsenic (0.34-5.4 mug g(-1) DM), whereas arsenobetaine, unlike the situation found in marine fish products, was not the major arsenic species (0.16 +/- 0.09 mug g(-1) DM). Smaller concentrations were found of arsenosugars la (0.18 +/- 0.11 mug g(-1) DM), 1b (0.077 +/- 0.049 mug g(-1) DM), 1c (0.080 +/- 0.089 mug g(-1) DM), and 1d (0.14 +/- 0.13 mug g(-1) DM). The presence of two unknown arsenic species was revealed (U1: 0.058 +/- 0.058 mug g(-1) DM; U2: 0.12 +/- 0.12 mug g(-1) DM). No significant differences were seen with respect to the total arsenic contents between the sexes. However, significant differences in the total arsenic contents were revealed between the area affected by the spill and the area not affected, the contents being greater in the affected area. Copyright (C) 2002 John Wiley Sons, Ltd.}, keywords = {arsenic, arsenic species, arsenobetaine, arsenosugars, ATOMIC-ABSORPTION SPECTROMETRY, CADMIUM, crayfish, crustacean, ENVIRONMENT, FISH, freshwater, LEAD, MASS-SPECTROMETRY, PERFORMANCE LIQUID-CHROMATOGRAPHY, SEAFOOD PRODUCTS, WATER MARSH}, isbn = {0268-2605}, url = {://000173868100002}, author = {Devesa, V. and Suner, M. A. and Lai, V. W. M. and Granchinho, S. C. R. and Martinez, J. M. and Velez, D. and Cullen, W. R. and Montoro, R.} } @article {362, title = {Distribution of arsenic species in the freshwater crustacean Procambarus clarkii}, journal = {Applied Organometallic Chemistry}, volume = {16}, number = {12}, year = {2002}, note = {ISI Document Delivery No.: 622PGTimes Cited: 2Cited Reference Count: 25}, month = {Dec}, pages = {692-700}, type = {Article}, abstract = {The concentrations of total arsenic and arsenic species in the complete organism of the crayfish Procambarus clarkii and its various parts (hepatopancreas, tail, and remaining parts) were analyzed in order to discover the distribution of arsenic and its species. With this information it will be possible to establish where the chemical forms of this metalloid tend to accumulate and what risks may derive from the contents and species present in the edible parts of this crustacean. The total arsenic content in the complete organism and in the various parts analyzed ranged from 2.5 to 12 mug g(-1) dry mass (DM), with inorganic arsenic representing 18 to 34\% of total arsenic. The arsenical composition varied according to the part of the crayfish considered. The hepatopancreas had the highest levels of total arsenic (9.2-12 mug g(-1) DM) and inorganic arsenic (2.7-3.2 mug g(-1) DM). The tail (edible part) had the lowest levels of both total arsenic (2.5-2.6 mug g(-1) DM) and inorganic arsenic (0.46-0.64 mug g(-1) DM). The predominant organoarsenical species were the dimethylarsinoylribosides: glycerol riboside in the hepatopancreas, sulfate riboside in the tail, and sulfonate and phosphate ribosides in the remaining parts. Copyright (C) 2002 John Wiley Sons, Ltd.}, keywords = {arsenic, arsenic species, arsenosugars, ATOMIC-ABSORPTION SPECTROMETRY, BIOACCUMULATION, crayfish, DIGESTION, ENVIRONMENT, FISH, freshwater, heptopancreas, MASS-SPECTROMETRY, PERFORMANCE LIQUID-CHROMATOGRAPHY, PRODUCTS, SEAFOOD, SPECIATION, tail muscle}, isbn = {0268-2605}, url = {://000179655000002}, author = {Devesa, V. and Suner, M. A. and Lai, V. W. M. and Granchinho, S. C. R. and Velez, D. and Cullen, W. R. and Martinez, J. M. and Montoro, R.} } @article {5085, title = {Biomethylation and bioaccumulation of arsenic(V) by marine alga Fucus gardneri}, journal = {Applied Organometallic Chemistry}, volume = {15}, number = {6}, year = {2001}, note = {ISI Document Delivery No.: 435TUTimes Cited: 14Cited Reference Count: 23}, month = {Jun}, pages = {553-560}, type = {Article}, abstract = {The brown alga, Fucus gardneri, was collected from Vancouver Island, B,C,, Canada. Fucus samples were acclimated in seawater and then exposed to arsenic(V) in artificial seawater, all under axenic conditions. The arsenic species in the Fucus samples were extracted into 1:1 methanol-H2O and identified by using ion-pairing high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS), Anion-exchange HPLC-ICP-MS was used to identify the arsenic species in the growth medium. It was found that similar to 73\% of the original arsenosugars in the F, gardneri samples were lost during the acclimation period. Arsenite [As(III)] and dimethylarsenate [DMA] concentration increased in the Fucus samples after exposure to arsenate [As(V)], A small increase in the concentration of an arsenosugar was seen during this period, accompanied by a further decrease in the concentration of two other arsenosugars. The experiments provided very little evidence for the hypothesis that arsenosugars are produced by the macroalgae. Copyright (C) 2001 John Wiley \& Sons, Ltd.}, keywords = {(ICP-MS), accumulation, ALGAE, arsenic, arsenite [As(III)], arsenosugar, biotransformation, chromatography (HPLC), dimethylarsenate [DMA], ENVIRONMENT, Fucus gardneri, high-performance liquid, IDENTIFICATION, inductively coupled plasma mass spectrometry}, isbn = {0268-2605}, url = {://000168897900015}, author = {Granchinho, S. C. R. and Polishchuk, E. and Cullen, W. R. and Reimer, K. J.} } @article {4879, title = {The adsorption of microcystin-LR by natural clay particles}, journal = {Toxicon}, volume = {38}, number = {2}, year = {2000}, note = {ISI Document Delivery No.: 257VLTimes Cited: 40Cited Reference Count: 35}, month = {Feb}, pages = {303-308}, type = {Article}, abstract = {The microcystin cyanobacterial hepatotoxins represent an increasingly severe global health hazard. Sines microcystins are found world wide in drinking water reservoirs concern about the impact on human health has prompted investigations into remedial water treatment methods. This preliminary study investigates the scavenging from water of microcystin-LR by fine-grained particles known to have a high concentration of the clay minerals kaolinite and montmorillonite. The results show that more than 81\% of microcystin-LR can be removed from water by clay material. Thus, microcystin-LR is indeed scavenged from water bodies by fine-grained particles and that this property may offer an effective method of stripping these toxins from drinking water supplies. (C) 1999 Elsevier Science Ltd. All rights reserved.}, keywords = {BLOOM, cyanobacteria, DECOMPOSITION, DIARRHETIC SHELLFISH TOXINS, ENVIRONMENT, IDENTIFICATION, OKADAIC ACID, OSCILLATORIA-AGARDHII, PROTEIN PHOSPHATASE INHIBITORS, TUMOR PROMOTION}, isbn = {0041-0101}, url = {://000083803000016}, author = {Morris, R. J. and Williams, D. E. and Luu, H. A. and Holmes, C. F. B. and Andersen, R. J. and Calvert, S. E.} } @article {4573, title = {The Norrish type II reaction in the crystalline state: Toward a better understanding of the geometric requirements for gamma-hydrogen atom abstraction}, journal = {Tetrahedron}, volume = {55}, number = {4}, year = {1999}, note = {ISI Document Delivery No.: 159BRTimes Cited: 69Cited Reference Count: 58}, month = {Jan}, pages = {885-907}, type = {Article}, abstract = {By correlating the success or failure of the Norrish type II reaction for a series of compounds in the crystalline state with geometric data derived from X-ray crystallography (the so-called Crystal Structure-Solid State Reactivity Method), the distance and angular requirements for photochemical gamma-hydrogen atom abstraction have been established. These studies indicate that abstractions are preferred when the C=O ... H-gamma, distance is close to the sum of the van der Waals radii of hydrogen and oxygen (2.72 Angstrom), and that the gamma-hydrogen atom can deviate by as much as 50-60 degrees from the plane containing the oxygen n-orbital responsible for abstraction. Because molecular conformations and interatomic distances and angles can be calculated readily by using empirical force field methods, such data permit predictions to be made concerning the outcome of hypothetical Norrish type II processes. (C) 1999 Elsevier Science Ltd. All rights reserved.}, keywords = {ABSOLUTE ASYMMETRIC-SYNTHESIS, CONFORMATIONAL CONTROL, ENVIRONMENT, KETONES, METHODOLOGY, MOLECULES, PHOTOCHEMISTRY, PHOTOCYCLIZATION, SOLID-STATE, SPECTRA}, isbn = {0040-4020}, url = {://000078152400001}, author = {Ihmels, H. and Scheffer, J. R.} } @article {4552, title = {The separation of dimethylarsinic acid, methylarsonous acid, methylarsonic acid, arsenate and dimethylarsinous acid on the Hamilton PRP-X100 anion-exchange column}, journal = {Applied Organometallic Chemistry}, volume = {13}, number = {11}, year = {1999}, note = {ISI Document Delivery No.: 255DLTimes Cited: 24Cited Reference Count: 29}, month = {Nov}, pages = {837-843}, type = {Article}, abstract = {In order to separate the potential arsenite metabolites methylarsonous acid and dimethylarsinous acid from arsenite, arsenate, methylarsonic acid and dimethylarsinic acid, the pH-dependent retention behaviour of all six arsenic compounds was studied on a Hamilton PRP-X100 anion-exchange column with 30 mM phosphate buffers (pH 5, 6, 7, 8 and 9) containing 20\% (v/v) methanol as mobile phase and employing an inductively coupled plasma atomic emission spectrometer (ICP-AES) as the arsenic-specific detector. Baseline separation of dimethylarsinic acid, methylarsonous acid, methylarsonic acid, arsenate and dimethylarsinous acid was achieved with a 30 mmol dm(-3) phosphate buffer (pH 5)-methanol mixture (80:20, v/v) in 25 min. Arsenite is not baseline-separated from dimethylarsinic acid under these conditions, Copyright (C) 1999 John Wiley \& Sons, Ltd.}, keywords = {ARSENATE, ARSENITE, BEHAVIOR, DIMETHYLARSINIC ACID, dimethylarsinous acid, ENVIRONMENT, ENZYMATIC METHYLATION, GLUTATHIONE, HPLC-ICP-AES, LAKE-BIWA, METABOLISM, METHYLARSENICALS, methylarsonic acid, methylarsonous acid, SPECIATION, SPECTROMETRY}, isbn = {0268-2605}, url = {://000083654200005}, author = {Gailer, J. and Madden, S. and Cullen, W. R. and Denton, M. B.} } @article {4287, title = {Metal(loid)organic compounds in geothermal gases and waters}, journal = {Organic Geochemistry}, volume = {29}, number = {5-7}, year = {1998}, note = {ISI Document Delivery No.: 156HQTimes Cited: 48Cited Reference Count: 5918th International Meeting on Organic GeochemistrySEP 22-26, 1997MAASTRICHT, NETHERLANDSEuropean Assoc Organ Geochemists}, pages = {1765-1778}, type = {Proceedings Paper}, abstract = {Volatile metal(loid)organic species of geogenic and anthropogenic origin are analyzed by low temperature gas chromatography coupled on-line with plasma mass spectrometry (LTGC/ICP MS) with detection limits in the higher pg-range (per m(3) gas). In respect to the determination of aqueous samples, this instrumental technique is combined with sample derivatization by the hydride generation technique. Volatile species of As, Sb, Sr and I could be detected in gases over hot springs in British Columbia (Canada). Methylated species of Hg, Ge, As, Sb and Te were also determined in concentrations in the ng/kg- to low mu g/kg-range in geothermal waters from Ruapehu, Waimangu, Waiotapu and Tokaanu (North Island, New Zealand); up to 1\% of the total dissolved metal(loid)s are found in methylated forms. Volatile metal(loid)organic species of geogenic origin are compared with those emanating from anthropogenic sources (waste and sewage gases, river and harbor sediments). Possible formation mechanisms for these compounds are discussed. (C) 1998 Elsevier Science Ltd. Ail rights reserved.}, keywords = {ANTIMONY, ATOMIC-ABSORPTION SPECTROMETRY, British Columbia, ENVIRONMENT, geothermal, hot springs, mercury, metal(loid)organic compounds, methylmercury, NATURAL-WATERS, New Zealand, NEW-ZEALAND, SEDIMENTS, sewage gases, VOLATILE METAL, volatile species, WASTE DEPOSITS, WASTE GASES, WATERS}, isbn = {0146-6380}, url = {://000077995900056}, author = {Hirner, A. V. and Feldmann, J. and Krupp, E. and Grumping, R. and Goguel, R. and Cullen, W. R.} } @article {3000, title = {BIOACCUMULATION AND EXCRETION OF ARSENIC COMPOUNDS BY A MARINE UNICELLULAR ALGA, POLYPHYSA-PENICULUS}, journal = {Applied Organometallic Chemistry}, volume = {8}, number = {4}, year = {1994}, note = {ISI Document Delivery No.: PD643Times Cited: 27Cited Reference Count: 43}, month = {Jul}, pages = {313-324}, type = {Article}, abstract = {Polyphysa peniculus was grown in artificial sea-water in the presence of arsenate, arsenite, monomethylarsonate and dimethylarsinic acid. The separation and identification of some of the arsenic species produced in the cells as well as in the growth medium were achieved by using hydride generation-gas chromatography-atomic absorption spectrometry methodology. Arsenite and dimethylarsinate were detected following incubation with arsenate. When the alga was treated with arsenite, dimethylarsinate was the major metabolite in the cells and in the growth medium; trace amounts of monomethylarsonate were also detected in the cells. With monomethylarsonate as a substrate, the metabolite is dimethylarsinate. Polyphysa peniculus did not metabolize dimethylarsinic acid when it was used as a substrate. Significant amounts of more complex arsenic species, such as arsenosugars, were not observed in the cells or medium on the evidence of flow injection-microwave digestion-hydride generation-atomic absorption spectrometry methodology. Transfer of the exposed cells to fresh medium caused release of most cell-associated arsenicals to the surrounding environment.}, keywords = {ARSENIC BIOACCUMULATION, ARSENIC METYLATION, arsenic species, ARSENIC UPTAKE, COMPOUNDS, CONTAINING RIBOFURANOSIDES, ENVIRONMENT, IDENTIFICATION, KELP ECKLONIA-RADIATA, METABOLISM, METHYLATION, NON-REDUCIBLE ARSENICALS, ORGANOARSENIC, PHYTOPLANKTON, POLYPHYSA-PENICULUS, RIVER BEAULIEU, SPECIATION}, isbn = {0268-2605}, url = {://A1994PD64300004}, author = {Cullen, W. R. and Harrison, L. G. and Li, H. and Hewitt, G.} } @article {3004, title = {DEGRADATION OF PHENANTHRENE AND PYRENE BY MICROORGANISMS ISOLATED FROM MARINE SEDIMENT AND SEAWATER}, journal = {Science of the Total Environment}, volume = {156}, number = {1}, year = {1994}, note = {ISI Document Delivery No.: PJ991Times Cited: 18Cited Reference Count: 40}, month = {Nov}, pages = {27-37}, type = {Article}, abstract = {Microorganisms which are able to degrade phenanthrene and pyrene were isolated from both seawater and sediment samples collected from a polycyclic aromatic hydrocarbon (PAH) polluted environment, Kitimat Arm, British Columbia, Canada. Four strains from a seawater culture were isolated and examined. No additional PAH induction was necessary in the enrichment process, indicating that these PAH degrading microorganisms are previously exposed to PAHs in the environment under study. Microorganisms enriched with phenanthrene as the sole carbon and energy source also degraded pyrene readily. A metabolite, pyrene cis-4,5-dihydrodiol was observed from pyrene degradation, and this metabolite was further degraded after pyrene was utilized by the microorganisms.}, keywords = {BIODEGRADATION, bioremediation, CONTAMINATED, DEGRADATION, ENVIRONMENT, ESTUARINE SEDIMENTS, MICROORGANISMS, MINERALIZATION, NAPHTHALENE, PAH, PHENANTHRENE, POLYCYCLIC AROMATIC HYDROCARBON, POLYCYCLIC AROMATIC-HYDROCARBONS, PYRENE, SEAWATER, SEDIMENT, SOIL}, isbn = {0048-9697}, url = {://A1994PJ99100004}, author = {Cullen, W. R. and Li, X. F. and Reimer, K. J.} } @article {3094, title = {EFFECT OF CYSTEINE ON THE SPECIATION OF ARSENIC BY USING HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROMETRY}, journal = {Analytica Chimica Acta}, volume = {285}, number = {3}, year = {1994}, note = {ISI Document Delivery No.: MV474Times Cited: 61Cited Reference Count: 41}, month = {Jan}, pages = {277-285}, type = {Article}, abstract = {The use of hydride generation techniques for arsenic species is pH dependent. Identical responses can not be obtained from arsenite, arsenate, monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) when the same acid concentration is used. Thus some methods commonly used for the direct determination of total arsenic under compromised conditions are subject to error. This error is eliminated by the addition of 2\% cysteine to samples prior to hydride generation. In the presence of cysteine the optimum condition for the determination of these arsenic species is in the same range, and a single arsenic species can be used for calibration. This finding is applied to the determination of arsenic in human urine by using flow injection, hydride generation, and atomic absorption spectrometry methodology. The effect of cysteine and thioglycerol is reported in detail, and it is proposed that arsenate, MMAA and DMAA all in the As(V) state, are reduced to the As(III) state as organo-sulfur-arsenic(III) compounds through the reaction between the arsenic species and the thiol. These products, organosulfur derivatives of arsenic(III), easily react with tetrahydroborate(III) under similar conditions to afford the arsines without interference from cysteine. Non-thiol-containing amino acids such as methionine, glycine and histidine do not react with arsenic species in this way, and therefore they do not affect the pH dependence of the generation of arsenic hydride species.}, keywords = {AMOUNTS, ANTIMONY, ARSENIC SPECIATION, ATOMIC ABSORPTION SPECTROMETRY, CHROMATOGRAPHY, CYSTEINE, EMISSION-SPECTROMETRY, ENVIRONMENT, FLOW INJECTION, HUMAN URINE, HYDRIDE GENERATION, INTERFERENCE REDUCTION, L-CYSTINE, NATURAL-WATERS, selenium, SPECTROSCOPY, TIN, TRACE}, isbn = {0003-2670}, url = {://A1994MV47400004}, author = {Le, X. C. and Cullen, W. R. and Reimer, K. J.} } @article {3003, title = {THE METHYLATION OF ARSENATE BY A MARINE ALGA POLYPHYSA-PENICULUS IN THE PRESENCE OF L-METHIONINE-METHYL-D(3)}, journal = {Chemosphere}, volume = {28}, number = {5}, year = {1994}, note = {ISI Document Delivery No.: NC959Times Cited: 13Cited Reference Count: 39}, month = {Mar}, pages = {1009-1019}, type = {Article}, abstract = {Polyphysa peniculus growing in artificial seawater methylates arsenate to produce a dimethylarsenic derivative, probably dimethylarsinate. When L-methionine-methyl-d3 is added to the culture the CD3 label is incorporated intact in the dimethylarsenic compound to a considerable extent, indicating that S-adenosylmethionine, or some related sulphonium compound, is involved in the biological methylation. Conclusive evidence of the CD3 incorporation was provided by using a specially developed hydride generation-gas chromatography-mass spectrometry methodology.}, keywords = {ALGAE, arsenic, COMPOUNDS, CONTAINING RIBOFURANOSIDES, ENVIRONMENT, GENERATION GAS CHROMATOGRAPHY MASS SPECTROMETRY (HG-GC-MS), hydride, IDENTIFICATION, KELP ECKLONIA-RADIATA, L-METHIONINE-METHYL-D(3), METHYLARSENIC COMPOUNDS, METHYLATION, NATURAL-WATERS, ORGANOARSENIC, REDUCTION, SPECIATION, SPECTROMETRY}, isbn = {0045-6535}, url = {://A1994NC95900016}, author = {Cullen, W. R. and Li, H. and Pergantis, S. A. and Eigendorf, G. K. and Harrison, L. G.} } @article {2769, title = {THE BIOTRANSFORMATION OF MONOMETHYLARSONATE AND DIMETHYLARSINATE INTO ARSENOBETAINE IN SEAWATER AND MUSSELS}, journal = {Applied Organometallic Chemistry}, volume = {7}, number = {5}, year = {1993}, note = {ISI Document Delivery No.: LV681Times Cited: 19Cited Reference Count: 12}, month = {Sep}, pages = {319-327}, type = {Article}, abstract = {Water-soluble H-3-labeled arsenic compounds were phenol-extracted from mussels (Mytilus edulis) and seawater after exposure to [H-3]monomethylarsonate (MMAA) and [H-3]dimethylarsinate (DMAA). Varying amounts of [H-3] arsenobetaine were found in mussels and seawater, depending upon the experimental conditions. The results indicate that arsenobetaine is principally biosynthesized by microscopic organisms in the seawater and that it is bioaccumulated by mussels. Total arsenic concentrations in mussel flesh, byssal threads and shells were also determined, showing concentration increases in all three compartments.}, keywords = {ARSENIC COMPOUNDS, arsenobetaine, DIMETHYLARSINATE, ENVIRONMENT, MONOMETHYLARSONATE, MUSSELS, SEAWATER}, isbn = {0268-2605}, url = {://A1993LV68100004}, author = {Cullen, W. R. and Nelson, J. C.} } @article {7295, title = {DECOMPOSITION OF ORGANOARSENIC COMPOUNDS BY USING A MICROWAVE-OVEN AND SUBSEQUENT DETERMINATION BY FLOW-INJECTION HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROMETRY}, journal = {Applied Organometallic Chemistry}, volume = {6}, number = {2}, year = {1992}, note = {ISI Document Delivery No.: HQ168Times Cited: 61Cited Reference Count: 33INTERNATIONAL CONF ON ENVIRONMENTAL AND BIOLOGICAL ASPECTS OF MAIN-GROUP ORGANOMETALS ( ICEBAMO )SEP 15-19, 1991PADUA, ITALYUNIV PADUA, ITALIAN CHEM SOC}, month = {Apr}, pages = {161-171}, type = {Proceedings Paper}, abstract = {Environmentally important organoarsenicals such as arsenobetaine, arsenocholine and tetramethylarsonium ion do not form volatile hydrides under the commonly used analytical conditions on treatment with borohydride and it has been difficult to determine their concentrations without further derivatization. This paper describes a rapid method which completely decomposes and oxidizes these arsenicals to arsenate by using potassium persulphate and sodium hydroxide with the aid of microwave energy. The quantitative decomposition of these species permits their determination at low nanogram levels, by hydride generation atomic absorption spectrometry (HG AA). A new hydride generator which has high efficiency and minimum dead volume and therefore is suitable for flow injection analysis (FIA) is also described. A system combining flow injection analysis, on-line microwave oven digestion, and hydride generation followed by atomic absorption measurement, is developed. This system is capable of performing analysis at a sample throughput of 100-120 per hour. Calibration curves were linear from 10 to 200 ng cm-3 of arsenic and the detection limit was 5 ng cm-3 for a 100-mu-l injection or 0.5 ng of arsenic. All ten organoarsenic compounds studied gave arsenate as the decomposition product, which was confirmed by using molybdenum blue photometric measurement.}, keywords = {ABSORPTION SPECTROMETRY, arsenic, arsenobetaine, atomic, DECOMPOSITION, DETERMINATION, DISSOLUTION, ENVIRONMENT, FLOW INJECTION ANALYSIS, HYDRIDE GENERATION, IDENTIFICATION, LIQUID-CHROMATOGRAPHY, MICROWAVE OVEN DIGESTION, MUSCLE REFERENCE MATERIAL, QUANTITATION, TRACE-ELEMENTS, WATER}, isbn = {0268-2605}, url = {://A1992HQ16800008}, author = {Le, X. C. and Cullen, W. R. and Reimer, K. J.} }