Brian E. McCarry

A new class of polyelectrolyte-filled microfiltration membranes with environmentally controlled porosity

Abstract A new type of membrane composed of a microfiltration substrate and a pore-filling polyelectrolyte has been produced by UV-induced grafting of 4-vinylpyridine onto polyethylene and polypropylene microfiltration membranes. By imposing the rigid structure of the polyolefinic substrate on the highly charged but extremely flexible and swellable gel of polyelectrolyte, stable membranes with very high charge density (> 3.5 mequiv/g) have been developed. The membranes show an outstanding pH valve effect and the capability of rejecting small inorganic ions in the process of reverse osmosis. The pressure-driven transport and separation with these membranes differ markedly from those of conventional reverse osmosis membranes being governed by the properties of the polyelectrolyte. Salt rejection depends strongly on the feed concentration, decreasing substantially with increase in concentration. The most characteristic features of separation with these membranes are higher rejection of polyvalent co-ions and lower rejection of polyvalent counter-ions compared to monovalent ions.

Benzyl isothiocyanate is the chief or sole anthelmintic in papaya seed extracts

Papaya (Carica papaya) seeds were extracted in an aqueous buffer or in organic solvents, fractionated by chromatography on silica and aliquots tested for anthelmintic activity by viability assays using Caenorhabditis elegans. For all preparations and fractions tested, anthelmintic activity and benzyl isothiocyanate content correlated positively. Aqueous extracts prepared from heat-treated seeds had no anthelmintic activity or benzyl isothiocyanate content although both appeared when these extracts were incubated with a myrosinase-containing fraction prepared from papaya seeds. A 10 h incubation of crude seed extracts at room temperature led to a decrease in anthelmintic activity and fractionated samples showed a lower benzyl isothiocyanate content relative to non-incubated controls. Benzyl thiocyanate, benzyl cyanide, and benzonitrile were not detected in any preparations and cyanogenic glucosides. which were present, could not account for the anthelmintic activity detected. Thus, our results are best explained if benzyl isothiocyanate is the predominant or sole anthelmintic agent in papaya seed extracts regardless of how seeds are extracted.

Porous, polyelectrolyte-filled membranes: Effect of cross-linking on flux and separation

Abstract A new type of membrane composed of a microfiltration substrate and a pore-filling polyelectrolyte has been produced by UV-induced grafting of 4-vinylpyridine (4VP) with varying amounts of divinylbenzene (DVB) onto polypropylene microfiltration membranes. Using the same irradiation conditions, it has been found that graft yield increases substantially in the presence of DVB. The increase in graft yield was shown to be accompanied by a substantial increase in the thickness of the grafted membranes and a small but significant decrease in water content. The composite membranes have very high charge densities and good mechanical properties. The membranes with various amounts of DVB were quaternized (methylated) and examined for reverse osmosis of various salts. In addition to an expected drop in flux due to the increased thickness and decreased water content, there was significantly different salt rejection for membranes with cross-linking. While, for example, there is practically no difference in rejection of NaCl by a membrane with 0.55% DVB and one having no cross-linker, the Na 2 SO 4 rejection by the cross-linked membrane is, on average, twice as high as that by the non-cross-linked one. Large differences between the cross-linked and non-cross-linked membranes were found in the ratios of pure water to NaCl permeate fluxes of the membranes at various pressures. The results are discussed in terms of the physicochemical nature of the membranes and conformational changes of the pore-grafted poly(4-vinylpyridine).

Preliminary comparisons between mutagenicity and magnetic susceptibility of respirable airborne particulate

The magnetic susceptibility of respirable urban airborne particulate and the mutagenic potency and organic content of extracts prepared from these particles are both related to mobile and stationary combustion processes. Analyses of the organic extracts prepared from these particulate samples showed the presence of certain polycyclic aromatic hydrocarbons (PAH), certain keto-PAH and thia-PAH. The enhanced magnetic signatures of air particulate material collected in an urban environment are directly related to the presence of magnetite-rich spherules which are likely to have been produced by the oxidation of pyrite to magnetite during the combustion process. A total of 62 filters collected between May 1990 and June 1991 at an air quality monitoring station in Hamilton, Ontario were examined. A plot of magnetic susceptibility of these filters and the mutagenic potencies of the organic extracts prepared from these filters in the Salmonella/microsome assay show a significant correlation. Neither magnetic susceptibility nor mutagenicity show a similar simple direct relationship to particulate loading. Plots of wind direction vs wind speed indicate that the highest mutagenicity and susceptibility levels are predominantly associated with (a) easterly derived winds, (b) low to moderate wind velocities, and (c) enhanced levels of SO2 and NO2. In contrast, low mutagenicity and susceptibility levels are intimately associated with (a) southwesterly derived winds, (b) moderate to high wind velocities, and (c) the presence of high ozone levels which accompany higher summer temperatures. These observations suggest that rapid magnetic susceptibility measurements could be used to pre-select filters for more extensive evaluations such as organic compound analyses or biological assays.

Compounds Structurally Related to Dechlorane Plus in Sediment and Biota from Lake Ontario (Canada)

The historical occurrence of Dechlorane Plus (DP) and detection of novel compounds structurally related to DP is described in a dated Lake Ontario sediment core. Our core was collected near the mouth of the Niagara River, which is known to be a major source of DP to the lake. Maximum DP concentrations (920 ng g(-1), dry weight) were observed between 1976 and 1980, the highest reported to date. Following that time, we observed a dramatic decrease in DP concentration which coincided with the enactment of United States federal and state laws to mitigate free release of chemicals into the Niagara River and installation of an industrial wastewater treatment facility. During the course of our research, four new substances structurally related to DP were also identified. These compounds were thought to arise from the Diels-Alder reactions resulting from impurities present in 1,5-cyclooctadiene, a feedstock used in production of DP. To confirm our hypothesis, Diels-Alder reactions were performed on the individual impurities. Using different stationary-phase capillary gas chromatography columns and high-resolution mass spectrometry, we were able to positively identify some of these novel compounds in the core. Interestingly, we also were able to identify a monoadduct compound, formed by addition of 1 mol of hexachlorocyclopentadiene to 2 mol of 1,3-cyclooctadiene, in lake trout. The concentration of this monoadduct was approximately 2 orders of magnitude greater than that of DP, suggesting that it is more bioaccumulative.

Analysis of high-molecular-mass polycyclic aromatic hydrocarbons in environmental samples using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

Polycyclic aromatic hydrocarbons (PAHs) with molecular masses higher than 300 u were analysed using LC-atmospheric pressure chemical ionization (APCI) MS in extracts of environmental samples from Hamilton, Canada including zebra mussels from Hamilton Harbour, air particulate and coal tar. The LC-APCI-MS profiles of three molecular mass classes of PAHs (326 u, 350 u and 374 u) were compared to identify potential sources of PAH contamination in Hamilton Harbour. The Hamilton air particulate profile was also compared with an urban air reference standard (NIST SRM 1649) from Washington, DC, USA. Profiles of all extracts were similar and suggested an environmental predominance of PAHs within the three isomeric molecular mass classes studied. However, PAHs of molecular mass 326 u and 350 u were detected in extracts of coal tar and zebra mussels from Hamilton Harbour but were not detected in Hamilton air. These results indicated that some high-molecular-mass PAHs may be characteristic of contamination by coal tar.

Formation of pore-filled ion-exchange membranes with in situ crosslinking: Poly(vinylbenzyl ammonium salt)-filled membranes

Robust, polyelectrolyte-filled, microporous membranes were prepared by the introduction and crosslinking of a preformed polymer within the pores of a poly(propylene) host membrane. Specifically, poly(vinylbenzyl chloride) (PVBCl) was reacted with piperazine or 1,4-diaminobicyclo[2.2.2]octane in an N,N-dimethylformamide (DMF) solution contained in the pores of the microporous base membrane. The remaining chloromethyl groups were reacted with an amine, such as trimethylamine, to form positively charged ammonium sites. This simple two-step procedure gave dimensionally stable, anion-exchange membranes in which the degree of crosslinking and the mass loading were determined by the concentration of PVBCl and crosslinker in the starting DMF solution. The incorporated polyelectrolyte gel was evenly distributed within the pores of the host membrane with no surface layers present. The membranes are fully characterized.

A Comparison of Ultrasonic Extraction and Soxhlet Extraction of Polycyclic Aromatic Hydrocarbons from Sediments and Air Particulate Material

Abstract The extraction of polycyclic aromatic hydrocarbons (PAH) from sediments and from an urban dust standard reference material (SRM 1649) was compared using two methods; ultrasonication and Soxhlet extraction. Sample weights ranging from 0.5 g to 5 g were extracted using ultrasonication. The yield of organic material from sediment samples using ultrasonication with two solvents was 2.53 ± 0.10% while the Soxhlet method yielded 2.41 ± 0.14% of the initial sample weight. Sequential ultrasonic extraction with two solvents was much more rapid (45 minutes) than Soxhlet extraction (two days) and resulted in equal extraction efficiency. The levels of PAH extracted by ultrasonication from the urban dust standard reference material varied by no more than 15% from the certified values.

A shotgun lipidomics approach in Sinorhizobium meliloti as a tool in functional genomics

A shotgun lipidomics approach that allowed the analysis of eight lipid classes directly from crude extracts of the soil bacterium Sinorhizobium meliloti is presented. New MS-MS transitions are reported for the analysis of monomethylphosphatidylethanolamines, dimethylphosphatidylethanolamines, and three bacterial non-phosphorus-containing lipid classes [sulfoquinovosyldiacylglycerols, ornithines, and diacylglyceryl-(N,N,N-trimethyl)-homoserines]. Unique MS-MS transitions allowed the analysis of isomeric species from various lipid classes without chromatography. Analyses required small sample amounts and minimal preparation; thus, this methodology has excellent potential to be used as a screening tool for the analysis of large numbers of samples in functional genomics studies. FA distributions within lipid classes of S. meliloti are described for the first time, and the relative positions of fatty acyl substituents (sn-1, sn-2) in phospholipids are presented. FA distributions in diacylglyceryl-(N,N,N-trimethyl)-homoserines were identical to those of phospholipids, indicating a common biosynthetic origin for these lipids. The method was applied to the analysis of mutants deficient in the PhoB regulator protein. Increased lipid cyclopropanation was observed in PhoB-deficient mutants under Pi starvation.

Chemical and biological profiles of sediments as indicators of sources of genotoxic contamination in Hamilton Harbour. Part I : Analysis of polycyclic aromatic hydrocarbons and thia-arene compounds

Bottom sediment and suspended sediment samples from Hamilton Harbour (western Lake Ontario) and from a major tributary were profiled using polycyclic aromatic hydrocarbons (PAH) and thia-arenes as source apportionment tracers. Ratios of selected PAH and ratios of monomethyl and dimethyl/ethyl dibenzothiophenes to the parent dibenzothiophenes were calculated. Thia-arene and PAH profiles of Standard Reference Material SRM 1649 (urban dust/organics), SRM 1650 (diesel), SRM 1597 (coal tar), Hamilton coal tar and a composite Hamilton air particulate sample provided source sample data. The gas chromatography-mass spectrometry (GC-MS) chromatograms of all sample extracts were dominated by homocyclic PAH but interpretation of PAH profiles with respect to source was difficult. In contrast, thia-arene analyses revealed more distinct differences in profiles of samples collected in different areas of the harbour, including the tributary. These results indicated that areas of coal tar-contaminated sediment are potential contributors to the overall contaminant burden of sediments and suspended sediments in Hamilton Harbour. These data also indicated that contaminants related to mobile combustion sources were entering the harbour via a major tributary.