1998 Spotlight on Graduate and
Undergraduate Research at ESF
ANOPHAGEFFERENS. Jeff Alexander, Darlene Szmyr and Gregory L. Boyer.
THE EFFECT OF IRON ON THE GROWTH OF THE BROWN TIDE ORGANISM, AUREOCOCCUS ANOPHAGEFFERENS. Jeff Alexander, Darlene Szmyr and Gregory L. Boyer.
CERIUM AMMONIUM NITRATE INDUCED CHIRAL OXYGENATION. Scott Corbin and Dr. Robert T. LaLonde.
RADIOACTIVE ISOTOPE DETECTION BY PHOSPHOIMAGERY. Mark Driscoll, Andrea E. Tobin and Neil P. J. Price.
UNIQUE STEROLS FROM GYMNODINIUM BREVIS BIOMARKERS FOR A RED TIDE ALGA? Juan Faraldos and Jose L. Giner.
ELECTROCHEMICAL OXIDATION SYSTEM FOR THE ANALYSIS OF PARALYTIC SHELLFISH (PSP) TOXINS IN NATURAL SHELLFISH SAMPLES. Gregory D. Goddard, K. Haya, and Gregory L. Boyer.
CHEMICAL ACTINOMETERS FOR UV LIGHT FLUX MEASUREMENTS: INTERCALIBRATION AND 1997 ANTARCTIC SPRINGTIME RESULTS. Joseph J. Jankowski, David J. Kieber, Kenneth Mopper, and Patrick J. Neale.
PARTICLES ON LEAVES. Venera Jouraeva, Dr. David Johnson, and Robert Hanna.
APPLICATION OF MERCURY CHELATORS TO DEVELOPMENT OF A PASSIVE SAMPLER FOR MERCURY IN WATER. Josef W. Kaser and John P. Hassett.
WATER SWELLABLE COPOLYMERS WITH LINEAR-DENDRITIC ARCHITECTURE. Kevin R. Lambrych and Dr. Ivan Gitsov.
LASER SPECTROSCOPY OF ALKOXY RADICALS AS A TOOL FOR ATMOSPHERIC CHEMISTRY. Michael D. Lilien, Liat G. Shemesh, and Theodore S. Dibble.
CONSTRUCTION AND COMPONENTS OF FUEL CELL. Han Liu, Cortney K. Mittelsteadt, Suoding Li, Youxin Yuan, Prof. Israel Cabasso.
MIREX AS A TRACER FOR MODELING LAKE DYNAMICS. Kelly A. Lowe and John P. Hassett.
ACTION SPECTRA FOR PHOTOCHEMICAL PRODUCTION OF HYDROGEN PEROXIDE IN NATURAL WATERS. Gary W. Miller, David J. Kieber, and Kenneth Mopper.
SYNTHESIS OF 9E,11Z-HEXADECADIENAL: SEX ATTRACTANT PHEROMONE OF THE PECAN NUT CASEBEARER, ACROBASIS NUXVORELLA NEUNZIG. Linda C. Passaro and Francis X. Webster.
INDIVIDUAL PARTICLE ANALYSIS FOR DEVELOPING LIGHT SCATTERING MODEL. Feng Peng and Dr. David L. Johnson.
FINDING SOURCES OF ORGANIC CONTAMINATION USING PISCES (PASSIVE IN SITU CONCENTRATION EXTRACTION SAMPLER). Jocelyn Polito, Donald Hughes and John Hassett.
DE-ACYLATION OF RHIZOBIUM NOD FACTORS BY FATTY ACYL AMIDASE II (FAA II). Peggy J. Sutherland, Andrea E. Tobin, Charles L. Rutherford, and Neil P.J. Price.
BIOSYNTHESIS OF 2-O-METHYLATED CAPSULAR POLYSACCHARIDE AND NODULATION FACTORS IN RHIZOBIUM FREDII USDA257: A COMMON METABOLIC PATHWAY. Andrea E. Tobin and Neil P.J. Price.
PREPARATION OF ANTIBODIES AGAINST FERRICROCIN. Tzu-Pin Wang, Jeff Alexander and Gregory L. Boyer.
ISOMERIZATION OF CYTOCHALASIN D TO CYTOCHALASIN C: A PROSPECTIVE ANTICANCER AGENT. Karie Wellington, Suzanne Hatfield, Tom Fondy and Neil Price.
THE INTERACTION BETWEEN SIDEROPHORES AND HEAVY METALS. Guozhang Zuo and Gregory L. Boyer.
IDENTIFICATION OF REACTIVE SPECIES RESPONSIBLE FOR PHOTODEGRADATION OF QUADRICYCLAN. Emily Zebrowski, Michelle Beretvas and John Hassett.
Jeff Alexander, Darlene Szmyr and Gregory L. Boyer, State University of New York, College of Environmental Science and Forestry, Syracuse, NY 13210.
Blooms of the Pelagophyte Aureococcus anophagefferens are responsible for the brown tides that occur in the Peconic estuary on Long Island. The occurrence of these blooms does not appear to be correlated with the level of macronutrients (N,P) present in the water column, and for this reason trace metals (Fe) have been implicated in controlling bloom formation. To investigate the effects of iron on the growth of this organism, A. anophagefferens (CCMP1708) was grown in trace metal defined artificial seawater. Two different conditions of iron availability were utilized; (1) iron was complexed with twice its concentration using EDTA, and (2) cultures were grown in trace metal buffered cultures using 100 (M excess EDTA. Growth was measured by in vivo fluorescence or visual cell counts. Both approaches gave the same result in that A. anophagefferens from the Peconic Estuary shows a very low iron requirement, the minimal iron quota below 10 nM. Low iron cultures showed little decrease in growth rate or growth yield. This is in agreement with the hypothesis of an oceanic origin for this species. The in vivo fluorescence per cell changes little with iron supply. Further experiments are in progress examining the effects of different chelators on the growth of Aureococcus, and if metabolic markers such as the ferredoxin /flavodoxin ratio or the ratio of variable to maximal fluorescence (Fv/Fm) can be used as an indicator of iron limitation in this species. This work was supported by New York Sea Grant and the Suffolk County Department of Health.
Blooms of the Pelagophyte Aureococcus anophagefferens are responsible for the brown tides that occur in the Peconic estuary on Long Island. The occurrence of these blooms does not appear to be correlated with the level of macronutrients (N,P) present in the water column, and for this reason trace metals (Fe) have been implicated in controlling bloom formation. To investigate the effects of iron on the growth of this organism, A. anophagefferens (CCMP1708) was grown in trace metal defined artificial seawater. Two different conditions of iron availability were utilized; (1) iron was complexed with twice its concentration using EDTA, and (2) cultures were grown in trace metal buffered cultures using 100 m M excess EDTA. Growth was measured by in vivo fluorescence or visual cell counts. Both approaches gave the same result in that A. anophagefferens from the Peconic Estuary shows a very low iron requirement, the minimal iron quota below 10 nM. Low iron cultures showed little decrease in growth rate or growth yield. This is in agreement with the hypothesis of an oceanic origin for this species. The in vivo fluorescence per cell changes little with iron supply. Further experiments are in progress examining the effects of different chelators on the growth of Aureococcus, and if metabolic markers such as the ferredoxin /flavodoxin ratio or the ratio of variable to maximal fluorescence (Fv/Fm) can be used as an indicator of iron limitation in this species. This work was supported by New York Sea Grant and the Suffolk County Department of Health.
In recent years, the importance of chiral compounds in the synthesis of pharmaceuticals has been realized. The focus of the research in our laboratory has been the development of a synthesis to induce optical activity in substituted benzhydrols by oxygenation of appropriately substituted diphenylmethanes with cerium ammonium nitrate (CAN). It is known that oxygenation of benzylic carbon of diphenylmethane in the presence of CAN and a carboxylic acid will give an ester at the benzylic carbon. Accordingly, if a chiral carboxylic acid is used a new chiral center at the benzylic carbon may be induced.
Radioisotopic tracing is an important technique in chemistry and biology that has traditionally relied on autoradiographic detection using X-ray film. In phosphoimagery, radioisotopic samples are exposed to a storage phosphor screens. The screens are subsequently "read" using a rapid, pulsed laser scanner, and the data is digitized for display and analysis. There are several advantages over the traditional use of X-ray film:- 1) The screens can be "read" in a normally lit room, and are then erased for reuse. Substantial time is saved compared to photographic development of X-ray film, without the need for a darkroom. Furthermore, phosphoimagery side-steps the problems of disposal of waste photographic chemicals and used film. 2) Phosphoimagers have 10-100 times greater sensitivity to radioisotopes than film, allowing substantially shorter exposure times (20-100 x faster than film) and the use of considerably less radioisotopic materials. This additional sensitivity often allows totally novel experiments to be performed that would otherwise require over long exposure times. Data can be analyzed in days rather than weeks or months. 3) Phosphoimagery allows detection of both strong and weak signals with a single exposure and has a 5 order of magnitude dynamic range (10-100 times that of film) with excellent linearity. Exposure of agarose and acrylamide gels, TLC plates, glass slides, microtiter plates, and blots are therefore feasible over a wide range of energies. These advantages are highlighted in this presentation.
Gymnodinium brevis is a marine dinoflagellate that causes
red tides. This organism is responsible for massive killings of fish, as well as human
poisoning, due to its production of potent neurotoxins, the brevetoxins.
1. Giner, J.L., "Biosynthesis of marine sterol side chains", Chem.Revs. 1993, 93, 1735-1752.
Paralytic shellfish poisoning occurs when shellfish feed on toxic dinoflagellates. A potent neurotoxin, saxitoxin accumulates in the shellfish and is passed up through the foodchain. We are studying two approaches to the detection of paralytic shellfish poison (PSP) toxins by HPLC. One protocol uses a post-column chemical reaction (PCRS) to oxidize the saxitoxin ring system to form a fluorescent chromophore1. The oxidation of the ring system is a critical component in the detection of saxitoxin and congeners. Serious disadvantages accompany the PCRS method, such as the precipitation of salts that can damage HPLC pumps and the need for careful control of flow rates. The oxidation of the saxitoxin ring system can also be achieved by electrochemical techniques (ECOS)1,2. These initial studies were conducted with standards and clean algal extracts. In this poster, we report on the comparison of the two methods of analysis for PSP toxins in shellfish. Analysis of saxitoxin and neosaxitoxin by ECOS techniques gave results that were comparable to the PCRS-HPLC method. The analyses of gonyuatoxins (GTX1-4) prove to be more difficult due to racemization of the different epimers. While shellfish extracts are a much more difficult sample matrix to work with, the simplicity of the ECOS approach makes it the preferred method for testing samples in the field.
The determination of ultraviolet (UV) light fluxes is
critical to the quantification of in situ photochemical and photobiological
processes in seawater. We developed a dual chemical actinometry system for the
determination of integrated scalar irradiances in seawater. The integrated scalar
irradiance below 330 nm is determined from the photolysis of nitrate. The photolysis of
nitrite is used to quantify the integrated scalar irradiance from 320 to 380 nm. The
nitrate and nitrite actinometers are based on the photoproduction of the hydroxyl radical
that is scavenged by benzoic acid to form salicylic acid. The salicylic acid is quantified
by high performance liquid chromatography with fluorescence detection.
Fine particles (less than 2.5 mm) are of a special concern from an environmental point of view. These particles are
enriched in carcinogenic substances. Due to their small size, they are not trapped in the
upper respiratory system and directly deposited in lungs, where their residence time is
months or years. Vegetative surfaces are known to be good collectors of small atmospheric
Passive samplers for hydrophobic organic compounds that operate by diffusion of hydrophobes from water through a polymer membrane and into a receiving solvent have been successfully developed and employed in our lab. Organic solvent-soluble chelators offer a route to a selective passive sampler for metal ions in water such as mercury. In this project two organic chelators, dithazone and dimercaptotoluene, have been examined to determine the feasibility of the uptake of mercury through a polymer membrane, polyethylene or cellulose, into an organic solvent from an aqueous mercury solution. The organic chelators were made up in isooctane and placed in a lab PISCES that was subsequently immerged in an aqueous 0.5mM mercuric nitrate solution. Samples were taken at 4 hours, 24 hours, and 6 days. The samples were back extracted using a 0.25N H2SO4, 0.5M KBr solution which was then analyzed by ICP-ES. Mercury was complexed and transported through the membrane into the organic solvent. This shows the considerable potential for future development of a passive mercury sampler.
Amphiphilic copolymers that are capable of swelling to form physical gel networks in aqueous media have potentially important applications in the environmental clean up field. The ability for the linear-dendritic copolymer [G4]-PEG11,000-[G4] to encapsulate environmentally dangerous polyaromatic hydrocarbons, PAHs, is analyzed in this study. N-methyl-4-(1-pyrene) vinyl pyridinium iodide is used as a model for PAH derivatives. Linear-dendritic architectures offer unique advantages over traditional linear copolymer architectures in that they have increased interstitial voids for the encapsulation of polyaromatic molecules placed in the intramolecular and intermolecular spaces formed by the dendritic fragment. In preliminary UV-Vis studies it was found that [G4]-PEG11,000-[G4] was able to completely encapsulate and bind N-methyl-4-(1-pyrene) vinyl pyridinium iodide in a aqueous environment within 24 hours. These are encouraging results for the employment of novel linear-dendritic copolymers in the removal or recycling of polyaromatic pollutants from internal, coastal, and groundwater resources. There are also several potential industrial applications such as utilization as phase-transfer agents and micro-reactors. Currently, kinetics studies on encapsulation and release of N-methyl-4-(1-pyrene) vinyl pyridinium iodide from [G4]-PEG11,000-[G4] are being conducted.
Alkoxy radicals are of key importance in atmospheric
chemistry. The chemistry of alkoxy radicals profoundly influences low altitude ozone
production both globally and in polluted environments. While the chemistry of small alkoxy
radicals has been well studied, the larger species have yet to be investigated directly.
A fuel cell is a device that converts the chemical energy
of the feed gases directly to electricity (see figure below). They represent a unique
alternative energy source with no emissions and efficiencies that are not bound by the
Carnot cycle. The components of the fuel cell are: A carbon-based anode with a thin layer
of surface catalyst for fuel gas oxidation (H2 in the current example); a
similar cathode for oxygen reduction; and a polymer electrolyte membrane for H+ transport.
Many pollutants, such as PCBs and dioxins, share similar
physical properties. For this class of compounds, sedimentation is the major removal
pathway of the pollutant in a lake. The rate of sedimentation is lake-specific, and varies
temporally and spatially, influenced mainly by plankton dynamics. Current models utilize
sediment cores to calculate annual average sedimentation rates, which leads to poor
precision in the model.
Hydrogen peroxide (H2O2) is ubiquitous in sunlit natural waters and is one of the major products formed from the photolysis of dissolved organic matter (DOM). Models have been developed to estimate photochemical production rates of H2O2 in natural waters. These models require, in part, wavelength dependent apparent quantum yield data for H2O2 production. Most H2O2 apparent quantum yield measurements to date have been made in fresh waters, while comparatively few measurements have been made in marine waters. Therefore, we determined apparent quantum yields for several coastal seawater samples as well as for samples from Antarctica. We observed that apparent quantum yields were remarkably similar among diverse aquatic environments suggesting the presence of similar precursors. We are now developing an algorithm to estimate wavelength dependent apparent quantum yields for H2O2 production given spectral measurements of DOM absorption.
The pecan nut casebearer, Acrobasis nuxvorella Neunzig, is one of the most significant pests to the pecan nut industry in the southwestern United States and Mexico. Extensive research has been aimed at finding more environmentally sound ways to manage and control the pecan nut casebearer. An alternative synthesis of 9E,11Z-hexadecadienal, the major sex attractant of the pecan nut casebearer has been carried out. Starting with 1-heptyn-3-ol, 9E,11Z-hexadecadienal was obtained in seven steps and characterized using NMR. Key transformations include an orthoester Claisen rearrangement, rearrangement of the product to a 2E,4Z-diene ester using basic Al2O3, and Cu(I)I coupling of 1-(tetrahydropyran-2-yloxy)-7-heptylmagnesium bromide to a diene acetate.
Turbidity, a measurement of water clarity, is accounted
for primarily by the absorption and scattering of lights by the suspended particles in
most freshwater systems1. It is our interest to partition the turbidity as a
function of size distribution of particles and of their chemical compositions.
1 Effler, S. W.; Wodka, M. C.; and Field, S. D. J. Env. Eng. Div., ASCE, 1984, 110, 1134-1145.
2 Jiao Jianfu, Ph.D. dissertation, 1991, Department of Chemistry, SUNY-College of Environmental Science and Forestry.
3 Skaneateles Lake Hydrodynamic/Turbidity Evaluation Report, 1995.
PISCES is a sampler for hydrophobic organic compounds (HOC) in natural bodies of water. It consists of a reservoir of solvent contained in a metal sampling device, with a window of polymer membrane separating the solvent from the water. HOCs diffuse across the membrane and accumulate in the solvent, mimicking the diffusion of HOCs across gill membrane of fish and bioconcentration within the tissues. PISCES are left in the field for about a month and resulting data obtained is time integrated. PISCES sampling rate have been calibrated in the laboratory for a variety of HOCs including naphthalene, chlorinated benzenes and polychlorinated biphenyls (PCB). The effects of temperature, degree of turbulence and different membranes have been investigated. PISCES has been used to monitor organic compounds in Onondaga Lake, NY, the Oswego River and elsewhere previously. We propose to extend the applicability of PISCES by investigating the uptake of a variety of polycyclic aromatic hydrocarbons (PAH). We plan to demonstrate the use of PISCES in the lower Hudson River and New York Harbor areas.
Dictyostelium discoideum (Amoebidae) secretes cell lysing enzymes; esterases, amidases and glycosylases, many of which degrade soil bacteria to provide a source of nutrients. Two of these enzymes, fatty acyl amidase I (FAA I) and fatty acyl amidase II (FAA II) act sequentially on the N-linked long chain acyl groups of lipid A, the lipid anchor of gram negative bacterial lipopolysaccharide (LPS). FAA I selectively hydrolyzes the 3-hydroxymyristroyl group N-linked to the proximal glucosamine residue of de-O-acylated lipid A. Substrate specificity for FAA II is less selective, but does require prior de-N-acylation of the proximal sugar, i.e. the bis-N-acylated lipid A is not a substrate. We have synthesized a 14C-labeled substrate analog for FAA II, and used this in a novel assay to monitor its purification. Inhibitory studies indicate that FAA II is not a serine protease but may have a catalytic mechanism similar to metalloprotein de-N-acetylases such as LpxC. Interestingly, Rhizobial Nod factor signal oligosaccharides that substrate recognition by FAA II. In vitro evidence indicate that R. fredii Nod factors are induce root nodules on leguminous plants have many of the structural requirements for selectively de-N-acylated by purified FAA II suggesting that the enzyme may reduce the N2-fixing efficiency of Rhizobium-legume symbioses. In contrast, N-methylated Nod factors from transgenic R. fredii carrying the rhizobial nodS gene were resistant to FAA II, suggesting a mechanism by which Nod factors may be protected from enzymatic de-N-acylation. Since FAA II and Nod factors are both secreted, and Nod factors that lack the N-acyl group are unable to induce nodules, dictyostelial FAA II may decrease the efficiency of symbiotic nitrogen fixation in the environment by reducing the available biologically active nodule inducer signal.
Rhizobium fredii USDA257 is a nitrogen-fixing bacteria that nodulates soybean. Nodulation is initiated upon secretion of Nod factor signal compounds synthesized by the microsymbiont. Rhizobial nodulation genes (noe, nod and nol), localized on the symbiotic plasmid, are important for determining host-specificity and biosynthesis of the nodulation factors. Nod genes noeI and nodS, for example, both encode for methyltransferase proteins. However, NoeI methylates a sugar residue at the 2-position, while NodS N-methylates the nonreducing terminal glucosamine residue on the Nod factor structure. Since the wild type strain does not carry an active nodS gene, the Rhizobium sp. NGR-234 nodS gene was cloned into 257pJFA31. Thus extending Rhizobium fredii's nodulation host range to include Leucaena. Rhizobium fredii USDA257 and 257pJFA31(NodS+) produce 2-O-methylfucose and fucose containing Nod factors and two capsular polysaccharides (CPS) consisting of mannose-Kdo repeating units and 2-O-methylmannose-Kdo repeating units. Upon induction of the nod genes with 5x10-4M apigenin, the Nod factors of both strains became labeled with [methyl-14C]methionine in the 2-O-methylfucose position. The 257pJFA31 strain also became labeled in the N-methyl position on the nonreducing glucosamine residue. The capsular polysaccharide, determined by the Kdo assay, became labeled with [methyl-14C]methionine in the 2-O-methylmannose portion of the disaccharide. After hydrolysis of the labeled disaccharide, the 2-O-methylmannose was isolated and characterized by GC/MS. Autoradiography-TLC, HPLC and LC/MS were utilized in confirming the presence of 2-O-methylfucose and 2-O-methylmannose in Nod factors and capsular polysaccharide. The evidence suggests that there may be a common precursor that is labeled with [methyl-14C]methionine and then feeds into both the inducible Nod factor biosynthetic pathway and CPS pathway.
Wilcoxina produces the siderophore ferricrocin (FCR) in iron-limited culture. To study the occurrence of FCR in forest soils and in mycorrhizia-plant associates, we are preparing antibodies against FCR. Ferricrocin was first reacted with succinic anhydride to give the FCR-hemisuccinate. This compound was purified by HPLC and gel chromatography, and characterized by NMR and mass spectroscopy. FCR-hemisuccinate was activated by 1-ethyl-3-(3-dimethyaminopropyl)carbodiimide-HCl and reacted with bovine serum albumin (BSA) or keyhole limpet hemocyanin (KLH), to yield BSA-succinate-FCR or KLH-succinate-FCR conjugate, respectively. These conjugates were characterized by SDS-PAGE, Csaky assay, and Bradford protein assay. KLH-succinate-FCR has hapten to protein ratio (mole/g) of 4.08 ¥ 10-4; and BSA-succinate-FCR has hapten to protein ratio (mole/g) of 2.37 ¥ 10-4. The KLH-succinate-FCR has sent for antibody generation. This antibody will be screened against the BSA-succinate-FCR conjugate, and used to develop an ELISA assay to determine siderophore concentration in roots and natural soils.
Cytochalasins are biologically active mold metabolites. The name "cytochalasin" refers to its diverse effects in cultured cells, which arises because cytochalasins disrupt the actin microfilament cytoskeleton and inhibit cytokinesis, the cytoplasmic dividing of a cell. The growth inhibiting capabilities of cytochalasins make them prospective anti-cancer chemotherapeutic agents, but this is limited by their inherent toxicity. In vivo testing in mice indicates that the different cytochalasin congeners vary in toxicity. Our goal was to convert cytochalasin D into cytochalasin C with an isomerization reaction under a hydrogen atmosphere. Cytochalasin C has been found to be ten times less toxic in mice than cytochalasin D but with essentially the same biological effectiveness against cells in culture. These two compounds differ only by the placement of a double bond. The isomerization reaction results in the changing of a methylene group in cytochalasin D to a methyl group in cytochalasin C. After filtration of the charcoal catalyst, cytochalasin C is isolated from any remaining cytochalasin D in the reaction product. On TLC plates the Rf value for cytochalasin D is higher than that of cytochalasin C. Therefore, they can be separated on C-18 reverse-phase thin layer chromatography plates in MeOH:H20 (75:25 v/v), and detected by fluorescence quenching. After isolation of cytochalasin C by preparative thin layer chromatography, the product has been tested for purity by proton NMR spectroscopy. The final purified product is being used for in vivo toxicity testing in Zebra Danio fish.
Siderophores are small peptides that are important in the chelation and uptake of ferric iron. These peptides may also bind other metals and provide a mechanism for the uptake for toxic heavy metals into the cell. We have purified the siderophore ferricrocin (FCR) from iron-limited cultures of Aspergillus sp. and characterized its structure by chromatographic and spectroscopic techniques. Ferricrocin forms strong complexes with aluminum and copper in addition to iron. Formation of the aluminum-FCR complex inhibited the formation of the ferri-ferricrocin complex as measured by HPLC using radioactive iron for detection. In contrast, prior addition of copper to form the copper-FCR complex stimulated the formation of the ferri-ferricrocin complex. The importance of this results for the uptake of heavy metals by fungi will be discussed.
Quadricyclane has been suggested as an alternative jet fuel by the air force. Prior to its use, research into the environmental fate of this compound has been undertaken. Studies have shown that quadricyclane does not undergo direct photolysis that is the action of sunlight alone does not cause degradation of the compound. However, in the presence of dissolved natural organic matter (humic acids), photodegradation can take place. Reactive intermediates formed by irradiation of the humic acids appear to react with quadricyclane. Experiments on the effects of pH, O2 concentration, ionic strength, humic acid concentration, hydroxyl radicals (OH.) and hydrated electrons indicate that the intermediates are superoxide (O2-) and hydroperoxy (HOO.) radicals. Ongoing work includes identification of the products of photolysis, the determination of wavelength dependence of the photodegradation of quadricyclane in different waters and field tests. The purpose of this is the eventual deployment of quadricyclane in natural bodies of water in order to probe the superoxide concentrations. It is likely that other chemicals present as contaminants in bodies of water will also react with superoxide and hence a simple measurement technique would be very useful.
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Last modified July 19, 1999