Harmonia axyridis (Coleoptera: Coccinellidae) (HA) was introduced into the United States from Jap... more Harmonia axyridis (Coleoptera: Coccinellidae) (HA) was introduced into the United States from Japan, the Republic of Korea, and the former USSR during the late 1970s and early 1980s (Nalepa et al. 1996) as a biocontrol tool for aphids and other insect pests (Chapin and Brou 1991). Its successful establishment in the northeastern United States and eastern Canada may have been accidental (Day et al. 1994), but it is now widespread throughout much of these regions (Hoebeke and Wheeler 1996) and has also been recorded in some western areas of the United States and Canada (Nalepa et al. 1996). Over the last decade there have been intermittent reports from the winemaker community in the eastern wine region of North America of an atypical aroma and flavor, reminiscent of crushed lady beetles, in some wines from the region. Typically, this has coincided with the observation of high numbers of HA beetles in vineyards and on the fruit at harvest, with as many as 20 to 50 beetles reported on some grape clusters (Martinson 2002). Coccinellids possess a reflex bleeding response of haemolymph when stressed (Al Abassi et al. 1998). The chemical composition of haemolymph has been partially determined and includes volatile compounds of known ol
Incorporation of powdered iron into the root bed of experimental constructed wetlands removes pho... more Incorporation of powdered iron into the root bed of experimental constructed wetlands removes phosphorus from treated sewage to levels that easily meet government guidelines for discharge into natural water bodies. Various combinations of powdered iron and sand were used to determine the best arrangement that removes the largest amount of phosphorus. Macrophytes fulfill a beneficial function by delivering oxygen to the root zone and by improving drainage in the wetland. In these wetlands, cattails (Typha latifolia L.) also take up phosphorus during growth and store significant quantities of it in their leaves.
Infrared sample digestion technology has been rapidly developed in recent years and its applicati... more Infrared sample digestion technology has been rapidly developed in recent years and its application and digestion performance on a variety of ores of base metals was assessed in this study, using a 6-channel infrared digester. Digestion times of 10 min or less were achieved for all base metal ores investigated, including oxides, sulfides, and silicates of Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Ti, W, and Zn. Performance criteria for all samples were excellent, reflected in z values of less than 2 in all cases. Various acid digestion methods were developed for the selected ore samples under high intensity infrared radiation and delivered virtually complete recoveries of all of the elements of interest. Chromite, the notoriously refractory chromium ore was digested within 10 min and gave 100% recovery of chromium. These digestions were accomplished without resorting to perchloric acid and, for most sample types, without hydrofluoric acid, significantly improving the workplace safety for analysts. Between-channel variation of the analyte recoveries from the 6-channel unit were generally below 2%, suggesting that the digestion methods developed with this platform provide reproducible results to meet various sample preparation demands. The high speed and analyte recovery of these digestions makes this methodology especially attractive for prospectors and developers who demand rapid and reliable results from exploration samples.
Grape-based products, including wine, are amongst the world's most important value-added horticul... more Grape-based products, including wine, are amongst the world's most important value-added horticultural commodities, both economically and culturally. 3-isobutyl-(IBMP) and 3-isopropyl-(IPMP) 2-methoxypyrazine are important grapeand insect-derived flavour compounds in some grape juices and wine, and are responsible for undesirable green characters associated with under-ripe grapes or infestation from Coccinellidae. Here we present data on two novel approaches to removing these compounds from juice and wine. Firstly, we describe a protein-based technology that binds and removes IPMP and IBMP in juice. The lipocalin Mouse Major Urinary Protein 1 (mMUP) was expressed in Pichia pastoris, secreted, and purified using anion exchange chromatography. mMUP, combined with a 10 KD cutoff PES membrane filtration system, resulted in a reduction of IPMP and IBMP in juice of > 98%. However, removal of methoxypyrazines from wine using this technique may be limited by ethanol-induced changes in the mMUP structure. Therefore, a 2 nd approach is being developed that takes advantage of the sorptive properties of various polymeric materials. A range of food-grade polyethylene-, polypropylene-and silicon-based polymers were evaluated for their capacity to remove IPMP and IBMP from red wine. Candidate polymers were standardized to a common surface area and added to red wine for 2 hrs. Quantification of IPMP and IBMP using HS-SPME-MD-GC-MS showed reductions of up to 40% for some polymers, and minimal changes to the sensory characteristics of the wine. We conclude there is capacity to significantly mediate the impact of methoxypyrazines on juice and wine quality using these biotechnology tools.
Sun: mary Inner salts of allylic amido-ammonium compounds are readily converted into derivatives ... more Sun: mary Inner salts of allylic amido-ammonium compounds are readily converted into derivatives of N-allyl-N 'A7'-dialkylhydrazinel and to 4-bromo-2,2-dialkylpyrazolitlinium salts.
In this article, we report a high-performance liquid chromatography-particle beam-mass spectromet... more In this article, we report a high-performance liquid chromatography-particle beam-mass spectrometric (HPLC-PB-MS) method for the determination of polycyclic aromatic hydrocarbons (PAHs). The PB interface consists of a concentric ultrasonic nebulizer with temperature-controlled desolvation chamber and a three-stage momentum separator. The HPLC-PB-MS method showed greater sensitivity for PAHs with molecular weights above 178 than for those PAHs with molecular weights below 178. The percent relative standard deviations for the determination of 0.5 ng chrysene, 1.0 ng dibcnzola.hlanthracenc, 1.0 ng benzo[g,h,i]perylene, and 2.5 ng coronene were 20%, 2.5%, 13.7%, and 6%, respectively. The detection limits at signal/noise~3 were 0.2 ng for chrysene, 1.0 ng for dibenzola.hjanthracene, 0.5 ng for benzo[g,h,i]perylene, and 1.5 ng for coronene.
Spectrochimica Acta Part B: Atomic Spectroscopy, 2005
A cold vapour (CV) generation system incorporating a modified version of a Multimode Sample Intro... more A cold vapour (CV) generation system incorporating a modified version of a Multimode Sample Introduction System (MSISk) was investigated for the determination of cadmium by atomic absorption spectrometry (AAS). The system allowed for the use of the relatively high concentrations of reagents required for efficient production of volatile cadmium without the significant bubbling, frothing, and associated liquid transport problems common to conventional gas-liquid separators while maintaining a low volume. The low volume produced narrow peaks (approximately 5 s base peak width). A detection limit of 0.026 Ag L À1 (3s) was found with a precision of 2.5% for a 0.5 Ag L À1 standard (n=4) and a linear dynamic range up to approximately 10 Ag L À1. The addition of thiourea, cobalt, and nickel was found to overcome interferences and produce good agreement between experimental and certified values for Natural Water and Mussel Tissue standard reference materials (SRM).
Spectrochimica Acta Part B: Atomic Spectroscopy, 1996
Four different designs of gas-liquid separators were compared for the determination of mercury by... more Four different designs of gas-liquid separators were compared for the determination of mercury by cold-vapour generation atomic absorption spectrometry using the sequential injection technique for mixing the reacting solutions. Two atom cells were also compared, one with windows and one without. The results indicate that the use of a "detuned" nebulizer gave the poorest results. Similar results were obtained with a home-made separator based on a flit and a Perkin-Elmer FIAS Chemifold system with a small dead volume. The use of an atom cell with windows provided the best signals for the determination of mercury.
The sediments of Lake Superior, Lake Huron, and Georgian Bay were sampled in 2001 and 2002 in ord... more The sediments of Lake Superior, Lake Huron, and Georgian Bay were sampled in 2001 and 2002 in order to evaluate the extent of surficial sediment contamination of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCs), polycyclic aromatic hydrocarbons (PAHs), and metals. Sediment concentrations of PCBs, OCs, PAHs, and mercury were generally low and up to 2 orders of magnitude less than in Lakes Erie and Ontario. In contrast, concentrations of metals such as arsenic, copper, and nickel were comparable to those in Lakes Erie and Ontario. These elevated Lakes Superior and Huron metal concentrations were attributed to naturally occurring metals within the bedrock, soil, and sediment of the study region. Concentrations of all contaminants were typically below the Canadian Sediment Quality Probable Effect Level (PEL) guidelines. With regard to spatial patterns, most contaminants were focused primarily in the depositional basins and atmospheric deposition was likely the major source of these chemicals to the lakes. The major exception was for metals (not including mercury) whose patterns were also influenced by natural sources as well as extensive mining activity. A comparison between surficial sediment contamination of samples collected as part of this survey and those collected in the late 1960s/early 1970s using similar methods showed that concentrations of DDT, PCB, lead, and mercury were generally similar between these two time periods. These results are not consistent with production and usage patterns that have declined substantially in the past 3 decades. We hypothesize that the lack of temporal trends is an artifact due to slow sediment accumulation rates as well as differences in analytical protocols between the two time periods.
, 2-isoprop op op op opyl-3-metho yl-3-metho yl-3-metho yl-3-metho yl-3-methoxyp xyp xyp xyp xypy... more , 2-isoprop op op op opyl-3-metho yl-3-metho yl-3-metho yl-3-metho yl-3-methoxyp xyp xyp xyp xypyr yr yr yr yrazine azine azine azine azine, taint , taint , taint , taint , taint
A solid phase microextraction (HS-SPME)-GC-MS methodology was established for the analysis of 3-a... more A solid phase microextraction (HS-SPME)-GC-MS methodology was established for the analysis of 3-alkyl-2-methoxypyrazines (MPs) in wine using a stable isotope dilution assay. The compounds analysed were 3-isobutyl-2-methoxypyrazine (IBMP), 3-sec-butyl-2-methoxypyrazine (SBMP), and 3-isopropyl-2-methoxypyrazine (IPMP) using their respective deuterated analogues ([ 2 H 3 ]-IBMP, [ 2 H 3 ]-SBMP, [ 2 H 3 ]-IPMP) as internal standards, synthesised during this work. A divinylbenzene/carboxene/polydimethylsiloxane (DVB/CAR/PDMS) fibre was selected for isolation of MPs and the effects of matrix parameters such as pH and ethanol concentration were examined in the development of the method. Best results were obtained at a pH of approximately 6 and with a wine dilution factor of 1:2.5, resulting in an ethanol concentration of approximately 5% (v/v). Relative standard deviations (RSDs) of replicate samples were 5.6-7% for all MPs at 5 ng L −1 and <5% for 15 and 30 ng L −1 samples. The limit of detection was <0.5 ng L −1 in juice and 1-2 ng L −1 in wine. The recovery efficiencies for spiked wine samples were between 99 and 102% for all three MPs. Using this method, we investigated the impact of the Multicoloured Asian Lady Beetle (MALB) on MPs in wine. In red wine fermented with live MALB, IPMP is the most prevalent MP detected, although SBMP concentrations are also increased and IBMP is unchanged from background levels. MALB that have been dead for 1 day before addition to juice can still contribute to elevated SBMP concentrations in wine, but not if they have been dead for 3 days or longer. Clarifying juice prior to fermentation leads to substantially lower IPMP concentration in the subsequent wine when compared with unclarified juice.
An automated reversed-phase high-performance liquid chromatographic (HPLC) method has been develo... more An automated reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the determination of trace concentrations of propoxur, carbofuran, carbaryl, propham, captan, chloropropham, barban and butylate in drinking water. A lOO-ml of sample water is passed through a 3-cm precolumn, packed with 5-pm ODS sorbent, at a flow-rate of 5 ml/min. The HPLC system is then switched to an acetonitrile-water gradient elution program. The analytes, which are concentrated on the precolumn, are eluted and separated on a 25-cm C8 analytical column and determined by measuring the UV absorption at 220 nm. The resolution of analytes is excellent regardless of whether the elution from the precolumn is done unidirectionally or with backflushing. The precolumn can be used repeatedly for at least 30 samples without a significant decrease in efficiency. The total analytical time is 60 min. Tap, distilled, deionized, commercial spring and HPLC-grade waters were analyzed. The lowest detectable concentrations are in the range of 10. 10-'2-460 lo-r2 g/ml for the eight pesticides with 100 ml of sample.
Temporal trends and seasonal variation of Dechloranes (Dec) 602, 603, 604, and Chlordene Plus (CP... more Temporal trends and seasonal variation of Dechloranes (Dec) 602, 603, 604, and Chlordene Plus (CP) in Niagara River suspended sediment, a Lake Ontario sediment core, and Lake Ontario lake trout were investigated, with Mirex and Dechlorane Plus (DP) included for comparison. Temporal concentration trends were generally consistent in each of the media for all compounds with the lowest concentrations observed in or after the late 1990s. In Niagara River suspended sediments, all compounds showed seasonal variation over a year with distinct profiles observed. The relative concentration patterns observed were total DP &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; Mirex &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; Dec 602 and Dec 604 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; Dec 603 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; CP in suspended sediments and sediment cores, whereas Mirex was highest in lake trout, followed by Dec 602 and DP. Dec 602 concentrations were 50 to 380 times greater than those of DP in lake trout, indicating Dec 602 has a greater bioaccumulation potential. The estimated biota-sediment accumulation factor (BSAF) for Dec 602 was much greater than for DP in Lake Ontario, and was greater than those calculated for PBDEs, indicating that assessment of some dechlorane compounds is merited if use is ongoing or planned.
A chlorinated compound (Chlordene Plus, CP), structurally related to Dechloranes (Dec) 602, 603, ... more A chlorinated compound (Chlordene Plus, CP), structurally related to Dechloranes (Dec) 602, 603, 604, and Dechlorane Plus (DP), was identified, and concentrations and spatial trends of Dec 602, 603, 604, CP, and DP in tributary sediments of the Laurentian Great Lakes are reported. The dechloranes were widely detected with their concentrations varying considerably across the Great Lakes basin. Spatial trends of Dec 602, 604, and DP in Canadian tributary sediments were similar to that of BDE 209, which suggested these flame retardant chemicals in tributaries were associated with industrial and urban areas. The highest concentrations of Dec 602, 604, and DP observed in tributaries of the Niagara River confirmed that past or ongoing manufacturing of these compounds at plants along the river were important sources to Lake Ontario. Dec 603 was detected in technical products of aldrin and dieldrin, and its spatial trend was consistent with historic pesticide usage. Similarly, CP was detected in technical products of chlordene and chlordane, and it was found in higher concentrations in sediments near urban areas, possibly related to past chlordane use in home termite control.
Harmonia axyridis (Coleoptera: Coccinellidae) (HA) was introduced into the United States from Jap... more Harmonia axyridis (Coleoptera: Coccinellidae) (HA) was introduced into the United States from Japan, the Republic of Korea, and the former USSR during the late 1970s and early 1980s (Nalepa et al. 1996) as a biocontrol tool for aphids and other insect pests (Chapin and Brou 1991). Its successful establishment in the northeastern United States and eastern Canada may have been accidental (Day et al. 1994), but it is now widespread throughout much of these regions (Hoebeke and Wheeler 1996) and has also been recorded in some western areas of the United States and Canada (Nalepa et al. 1996). Over the last decade there have been intermittent reports from the winemaker community in the eastern wine region of North America of an atypical aroma and flavor, reminiscent of crushed lady beetles, in some wines from the region. Typically, this has coincided with the observation of high numbers of HA beetles in vineyards and on the fruit at harvest, with as many as 20 to 50 beetles reported on some grape clusters (Martinson 2002). Coccinellids possess a reflex bleeding response of haemolymph when stressed (Al Abassi et al. 1998). The chemical composition of haemolymph has been partially determined and includes volatile compounds of known ol
Incorporation of powdered iron into the root bed of experimental constructed wetlands removes pho... more Incorporation of powdered iron into the root bed of experimental constructed wetlands removes phosphorus from treated sewage to levels that easily meet government guidelines for discharge into natural water bodies. Various combinations of powdered iron and sand were used to determine the best arrangement that removes the largest amount of phosphorus. Macrophytes fulfill a beneficial function by delivering oxygen to the root zone and by improving drainage in the wetland. In these wetlands, cattails (Typha latifolia L.) also take up phosphorus during growth and store significant quantities of it in their leaves.
Infrared sample digestion technology has been rapidly developed in recent years and its applicati... more Infrared sample digestion technology has been rapidly developed in recent years and its application and digestion performance on a variety of ores of base metals was assessed in this study, using a 6-channel infrared digester. Digestion times of 10 min or less were achieved for all base metal ores investigated, including oxides, sulfides, and silicates of Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Ti, W, and Zn. Performance criteria for all samples were excellent, reflected in z values of less than 2 in all cases. Various acid digestion methods were developed for the selected ore samples under high intensity infrared radiation and delivered virtually complete recoveries of all of the elements of interest. Chromite, the notoriously refractory chromium ore was digested within 10 min and gave 100% recovery of chromium. These digestions were accomplished without resorting to perchloric acid and, for most sample types, without hydrofluoric acid, significantly improving the workplace safety for analysts. Between-channel variation of the analyte recoveries from the 6-channel unit were generally below 2%, suggesting that the digestion methods developed with this platform provide reproducible results to meet various sample preparation demands. The high speed and analyte recovery of these digestions makes this methodology especially attractive for prospectors and developers who demand rapid and reliable results from exploration samples.
Grape-based products, including wine, are amongst the world's most important value-added horticul... more Grape-based products, including wine, are amongst the world's most important value-added horticultural commodities, both economically and culturally. 3-isobutyl-(IBMP) and 3-isopropyl-(IPMP) 2-methoxypyrazine are important grapeand insect-derived flavour compounds in some grape juices and wine, and are responsible for undesirable green characters associated with under-ripe grapes or infestation from Coccinellidae. Here we present data on two novel approaches to removing these compounds from juice and wine. Firstly, we describe a protein-based technology that binds and removes IPMP and IBMP in juice. The lipocalin Mouse Major Urinary Protein 1 (mMUP) was expressed in Pichia pastoris, secreted, and purified using anion exchange chromatography. mMUP, combined with a 10 KD cutoff PES membrane filtration system, resulted in a reduction of IPMP and IBMP in juice of > 98%. However, removal of methoxypyrazines from wine using this technique may be limited by ethanol-induced changes in the mMUP structure. Therefore, a 2 nd approach is being developed that takes advantage of the sorptive properties of various polymeric materials. A range of food-grade polyethylene-, polypropylene-and silicon-based polymers were evaluated for their capacity to remove IPMP and IBMP from red wine. Candidate polymers were standardized to a common surface area and added to red wine for 2 hrs. Quantification of IPMP and IBMP using HS-SPME-MD-GC-MS showed reductions of up to 40% for some polymers, and minimal changes to the sensory characteristics of the wine. We conclude there is capacity to significantly mediate the impact of methoxypyrazines on juice and wine quality using these biotechnology tools.
Sun: mary Inner salts of allylic amido-ammonium compounds are readily converted into derivatives ... more Sun: mary Inner salts of allylic amido-ammonium compounds are readily converted into derivatives of N-allyl-N 'A7'-dialkylhydrazinel and to 4-bromo-2,2-dialkylpyrazolitlinium salts.
In this article, we report a high-performance liquid chromatography-particle beam-mass spectromet... more In this article, we report a high-performance liquid chromatography-particle beam-mass spectrometric (HPLC-PB-MS) method for the determination of polycyclic aromatic hydrocarbons (PAHs). The PB interface consists of a concentric ultrasonic nebulizer with temperature-controlled desolvation chamber and a three-stage momentum separator. The HPLC-PB-MS method showed greater sensitivity for PAHs with molecular weights above 178 than for those PAHs with molecular weights below 178. The percent relative standard deviations for the determination of 0.5 ng chrysene, 1.0 ng dibcnzola.hlanthracenc, 1.0 ng benzo[g,h,i]perylene, and 2.5 ng coronene were 20%, 2.5%, 13.7%, and 6%, respectively. The detection limits at signal/noise~3 were 0.2 ng for chrysene, 1.0 ng for dibenzola.hjanthracene, 0.5 ng for benzo[g,h,i]perylene, and 1.5 ng for coronene.
Spectrochimica Acta Part B: Atomic Spectroscopy, 2005
A cold vapour (CV) generation system incorporating a modified version of a Multimode Sample Intro... more A cold vapour (CV) generation system incorporating a modified version of a Multimode Sample Introduction System (MSISk) was investigated for the determination of cadmium by atomic absorption spectrometry (AAS). The system allowed for the use of the relatively high concentrations of reagents required for efficient production of volatile cadmium without the significant bubbling, frothing, and associated liquid transport problems common to conventional gas-liquid separators while maintaining a low volume. The low volume produced narrow peaks (approximately 5 s base peak width). A detection limit of 0.026 Ag L À1 (3s) was found with a precision of 2.5% for a 0.5 Ag L À1 standard (n=4) and a linear dynamic range up to approximately 10 Ag L À1. The addition of thiourea, cobalt, and nickel was found to overcome interferences and produce good agreement between experimental and certified values for Natural Water and Mussel Tissue standard reference materials (SRM).
Spectrochimica Acta Part B: Atomic Spectroscopy, 1996
Four different designs of gas-liquid separators were compared for the determination of mercury by... more Four different designs of gas-liquid separators were compared for the determination of mercury by cold-vapour generation atomic absorption spectrometry using the sequential injection technique for mixing the reacting solutions. Two atom cells were also compared, one with windows and one without. The results indicate that the use of a "detuned" nebulizer gave the poorest results. Similar results were obtained with a home-made separator based on a flit and a Perkin-Elmer FIAS Chemifold system with a small dead volume. The use of an atom cell with windows provided the best signals for the determination of mercury.
The sediments of Lake Superior, Lake Huron, and Georgian Bay were sampled in 2001 and 2002 in ord... more The sediments of Lake Superior, Lake Huron, and Georgian Bay were sampled in 2001 and 2002 in order to evaluate the extent of surficial sediment contamination of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCs), polycyclic aromatic hydrocarbons (PAHs), and metals. Sediment concentrations of PCBs, OCs, PAHs, and mercury were generally low and up to 2 orders of magnitude less than in Lakes Erie and Ontario. In contrast, concentrations of metals such as arsenic, copper, and nickel were comparable to those in Lakes Erie and Ontario. These elevated Lakes Superior and Huron metal concentrations were attributed to naturally occurring metals within the bedrock, soil, and sediment of the study region. Concentrations of all contaminants were typically below the Canadian Sediment Quality Probable Effect Level (PEL) guidelines. With regard to spatial patterns, most contaminants were focused primarily in the depositional basins and atmospheric deposition was likely the major source of these chemicals to the lakes. The major exception was for metals (not including mercury) whose patterns were also influenced by natural sources as well as extensive mining activity. A comparison between surficial sediment contamination of samples collected as part of this survey and those collected in the late 1960s/early 1970s using similar methods showed that concentrations of DDT, PCB, lead, and mercury were generally similar between these two time periods. These results are not consistent with production and usage patterns that have declined substantially in the past 3 decades. We hypothesize that the lack of temporal trends is an artifact due to slow sediment accumulation rates as well as differences in analytical protocols between the two time periods.
, 2-isoprop op op op opyl-3-metho yl-3-metho yl-3-metho yl-3-metho yl-3-methoxyp xyp xyp xyp xypy... more , 2-isoprop op op op opyl-3-metho yl-3-metho yl-3-metho yl-3-metho yl-3-methoxyp xyp xyp xyp xypyr yr yr yr yrazine azine azine azine azine, taint , taint , taint , taint , taint
A solid phase microextraction (HS-SPME)-GC-MS methodology was established for the analysis of 3-a... more A solid phase microextraction (HS-SPME)-GC-MS methodology was established for the analysis of 3-alkyl-2-methoxypyrazines (MPs) in wine using a stable isotope dilution assay. The compounds analysed were 3-isobutyl-2-methoxypyrazine (IBMP), 3-sec-butyl-2-methoxypyrazine (SBMP), and 3-isopropyl-2-methoxypyrazine (IPMP) using their respective deuterated analogues ([ 2 H 3 ]-IBMP, [ 2 H 3 ]-SBMP, [ 2 H 3 ]-IPMP) as internal standards, synthesised during this work. A divinylbenzene/carboxene/polydimethylsiloxane (DVB/CAR/PDMS) fibre was selected for isolation of MPs and the effects of matrix parameters such as pH and ethanol concentration were examined in the development of the method. Best results were obtained at a pH of approximately 6 and with a wine dilution factor of 1:2.5, resulting in an ethanol concentration of approximately 5% (v/v). Relative standard deviations (RSDs) of replicate samples were 5.6-7% for all MPs at 5 ng L −1 and <5% for 15 and 30 ng L −1 samples. The limit of detection was <0.5 ng L −1 in juice and 1-2 ng L −1 in wine. The recovery efficiencies for spiked wine samples were between 99 and 102% for all three MPs. Using this method, we investigated the impact of the Multicoloured Asian Lady Beetle (MALB) on MPs in wine. In red wine fermented with live MALB, IPMP is the most prevalent MP detected, although SBMP concentrations are also increased and IBMP is unchanged from background levels. MALB that have been dead for 1 day before addition to juice can still contribute to elevated SBMP concentrations in wine, but not if they have been dead for 3 days or longer. Clarifying juice prior to fermentation leads to substantially lower IPMP concentration in the subsequent wine when compared with unclarified juice.
An automated reversed-phase high-performance liquid chromatographic (HPLC) method has been develo... more An automated reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the determination of trace concentrations of propoxur, carbofuran, carbaryl, propham, captan, chloropropham, barban and butylate in drinking water. A lOO-ml of sample water is passed through a 3-cm precolumn, packed with 5-pm ODS sorbent, at a flow-rate of 5 ml/min. The HPLC system is then switched to an acetonitrile-water gradient elution program. The analytes, which are concentrated on the precolumn, are eluted and separated on a 25-cm C8 analytical column and determined by measuring the UV absorption at 220 nm. The resolution of analytes is excellent regardless of whether the elution from the precolumn is done unidirectionally or with backflushing. The precolumn can be used repeatedly for at least 30 samples without a significant decrease in efficiency. The total analytical time is 60 min. Tap, distilled, deionized, commercial spring and HPLC-grade waters were analyzed. The lowest detectable concentrations are in the range of 10. 10-'2-460 lo-r2 g/ml for the eight pesticides with 100 ml of sample.
Temporal trends and seasonal variation of Dechloranes (Dec) 602, 603, 604, and Chlordene Plus (CP... more Temporal trends and seasonal variation of Dechloranes (Dec) 602, 603, 604, and Chlordene Plus (CP) in Niagara River suspended sediment, a Lake Ontario sediment core, and Lake Ontario lake trout were investigated, with Mirex and Dechlorane Plus (DP) included for comparison. Temporal concentration trends were generally consistent in each of the media for all compounds with the lowest concentrations observed in or after the late 1990s. In Niagara River suspended sediments, all compounds showed seasonal variation over a year with distinct profiles observed. The relative concentration patterns observed were total DP &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; Mirex &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; Dec 602 and Dec 604 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; Dec 603 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; CP in suspended sediments and sediment cores, whereas Mirex was highest in lake trout, followed by Dec 602 and DP. Dec 602 concentrations were 50 to 380 times greater than those of DP in lake trout, indicating Dec 602 has a greater bioaccumulation potential. The estimated biota-sediment accumulation factor (BSAF) for Dec 602 was much greater than for DP in Lake Ontario, and was greater than those calculated for PBDEs, indicating that assessment of some dechlorane compounds is merited if use is ongoing or planned.
A chlorinated compound (Chlordene Plus, CP), structurally related to Dechloranes (Dec) 602, 603, ... more A chlorinated compound (Chlordene Plus, CP), structurally related to Dechloranes (Dec) 602, 603, 604, and Dechlorane Plus (DP), was identified, and concentrations and spatial trends of Dec 602, 603, 604, CP, and DP in tributary sediments of the Laurentian Great Lakes are reported. The dechloranes were widely detected with their concentrations varying considerably across the Great Lakes basin. Spatial trends of Dec 602, 604, and DP in Canadian tributary sediments were similar to that of BDE 209, which suggested these flame retardant chemicals in tributaries were associated with industrial and urban areas. The highest concentrations of Dec 602, 604, and DP observed in tributaries of the Niagara River confirmed that past or ongoing manufacturing of these compounds at plants along the river were important sources to Lake Ontario. Dec 603 was detected in technical products of aldrin and dieldrin, and its spatial trend was consistent with historic pesticide usage. Similarly, CP was detected in technical products of chlordene and chlordane, and it was found in higher concentrations in sediments near urban areas, possibly related to past chlordane use in home termite control.
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