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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2005.01.031 Byline: R. Hites, Y. De Smet, N. Risse, M. Salazar-Neumann, P. Vincke Keywords: Multicriteria analysis; Robustness Abstract: Coping with uncertainties or ignorance in decision problems may lead to the idea that several scenarios can occur or that several sets of data can constitute a good representation of the reality. In consequence, numerous authors have focused on the robust aspect of these problems. In such a context, one can consider that a scenario (or a particular instance of the data) permits to partially qualify the solutions, just as a criterion does. In other words, the evaluation of a specific solution for a given scenario could be perceived as the evaluation of this solution according to one particular criterion. With this in mind, the applicability of classic multicriteria concepts to the robustness framework, in the context of optimization problems, is explored. We achieve this by studying their similarities and differences. The distinguishing characteristics bring us to introduce a new problematic: the multicriteria evaluation of robustness. Author Affiliation: Service de Mathematiques de la Gestion, Universite Libre de Bruxelles, Blvd du Triomphe CP 210/01, B-1050 Bruxelles, Belgium Article History: Received 17 October 2003; Accepted 10 January 2005

Data are presented on the limits of detection for a series of nine compounds in negative chemical ionization (NCI) mass spectra obtained in five different mass spectrometers: Finnigan 4000 with a 4500 ion source, Kratos MS-80, Hewlett-Packard 5985 and two Finnigan 4500s. The nine compounds undergo either resonance capture or dissociative capture of an electron at optimum energies ranging from 0.0 to 1.1 eV. The limits of detection generally increased with increasing optimum electron energy. The limit of detection as a function of optimum electron capture energy is expected to provide information about the electron energy distribution in the ion sources. The data showed scatter within and between instruments. The scatter is believed to be due primarily to reactions with low levels of adventitious gases such as oxygen in the ion source. The data also suggested wide variations in electron energies between the instruments. The variation in the electron energy distribution is thought to have been caused by variations in the ion optical fields within the instruments. These results suggest that the requirements for reproducibility in NCI mass spectra at the limit of detection are rigorous control of trace gases in the ion source, control of the electric fields within the source including ion optical fields that penetrate the source aperture control of pressure, temperature and other factors that influence NCI mass spectra. [ABSTRACT FROM AUTHOR]

The Great Lakes have been the focus of extensive environmental research, but recent data on the aquatic concentrations of emerging compounds, such as flame retardants, are scarce. Water samples from 18 stations on the five Great Lakes were collected in 2011 and 2012 using XAD-2 resin adsorption and analyzed for PCBs, organochlorine pesticides, PAHs, polybrominated diphenyl ethers (PBDEs), and emerging flame retardants, including organophosphate flame retardants (OPEs). Total PCB concentrations ranged from 117 ± 18 pg/L in Lake Superior to 623 ± 113 pg/L in Lake Ontario. Among the organochlorine pesticides, the most abundant was dieldrin, with the highest average concentration of 99 ± 26 pg/L in Lake Erie, followed by p,p'-DDD with an average concentration of 37 ± 8 pg/L in Lake Ontario. Total PAH concentrations were higher in Lakes Erie and Ontario than in Lakes Michigan, Huron, and Superior. Total PBDE concentrations were highest in Lake Ontario (227 ± 75 pg/L), and the most abundant congeners were BDE-47, BDE-99, and BDE-209. Total OPE concentrations ranged between 7.3 ± 4.5 ng/L in Lake Huron to 96 ± 43 ng/L in Lake Erie.

A series of experiments were conducted among the laboratories participating in the Integrated Atmospheric Deposition Network (IADN) monitoring program to evaluate comparability of the reported persistent organic pollutant concentrations. This quality assurance activity is essential because a variety of methods are currently used for sample collection, extraction, and analysis by the IADN laboratories. The experiments included analyses of a common reference standard (CRS), analyses of split samples, and analyses of samples collected with co-located samplers at the Point Petre IADN measurement station. The analytes included polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs). For virtually all compounds, the laboratories produced generally comparable results for the CRS samples, the split samples and the co-location samples, although some differences were observed. Analysis of the methods may pinpoint areas where variations in the methods will result in the differences observed in the reported data. These differences can be due to the field sampling process, the analytical method, field blank values, or a combination of all these factors. This study points out the importance of QA activities at every step of an environmental monitoring process so that areas where improvements may be needed or where inconsistencies may exist can be identified.

The pesticide toxaphene was used extensively on cotton in the southern United States until its use was restricted in 1982. It was previously reported that the upper Great Lakes have received toxaphene by gas absorption following long-range transport from the south and are currently saturated with respect to toxaphene. However, the rate of loss of toxaphene from Lakes Michigan and Superior had been estimated using sparse or estimated data, and thus, these estimates had high uncertainties. For this investigation, samples were collected to provide extensive data on air, water, and sediment concentrations of toxaphene for the upper Great Lakes for the period 1997-98. These data were used to calculate the annual and seasonal fluxes of toxaphene from water to air and sediment. Lake Superior is 200-1000% saturated with toxaphene, and Lake Michigan is 200-500% saturated. It seems clear that both lakes will outgas toxaphene into the atmosphere for some considerable time in the future, and Lake Superior, because of its generally lower water temperatures and higher toxaphene concentration, will outgas toxaphene even longer than will Lake Michigan.

Wine corks were extracted and analyzed for 23 organochlorine pesticides, including alpha-, beta-, and gamma-hexachlorocyclohexanes (HCH), hexachlorobenzene, DDT, DDE and DDD, chlordane, endosulfan, dieldrin, aldrin, and endrin. This was done to investigate the occurrence, concentrations, composition profiles, and possible sources of organochlorine contamination. All groups of compounds were detected in every sample investigated, with the exception of aldrin and endrin. The total concentrations of organochlorine compounds in all samples ranged from 75-120 ng/g lipid, and for most compounds, the concentrations of organochlorines in cork were consistent with published data for other plant tissues. Differences in the relative abundances of the various classes of organochlorine pesticides were substantial and were probably due to differences in the pesticide usage practices of the various regions in which the cork producing trees were grown.

Atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and pesticides were compared at Brule River and Eagle Harbor, two rural sites on Lake Superior that are part of the Integrated Atmospheric Deposition Network (IADN). Brule River lies 40 km southwest of Duluth, MN, a small industrial city, and Eagle Harbor is in Michigan's upper peninsula, 400 km east of Brule River. Pesticide and PCB concentrations were similar at both sites. Day-by-day regression analyses of the data showed that PAH concentrations, an indication of urban contamination, were significantly higher at Brule Riverthan at Eagle Harbor. Concentration ranges for all compounds at both sites were well within global background levels, despite the differences observed between the two sites. Clearly, pollution from Duluth is influencing PAH concentrations at Brule River more than at Eagle Harbor.

Since cyclodextrin gas chromatography columns became popular for chiral separations, many researchers have noticed high enantiomeric ratios [ER: (+)-enantiomer/(-)-enantiomer] for alpha-HCH in the brains of wildlife. This investigation used the laboratory rat as a model for these phenomena. Rats were either pretreated with phenobarbital (PB) or left untreated and then dosed with alpha-HCH. Animals were sacrificed after 1 or 24 h. The ER averaged 0.95 +/- 0.01 in blood, 1.29 +/- 0.02 in fat, and 0.77 +/- 0.004 in liver. ERs in brain ranged from 2.8 +/- 0.5 to 13.5 +/- 0.4. Both the tissue concentration distribution and the ERs agree well with those previously reported in wildlife. To determine whether high brain ERs were due to enantioselective metabolism or transport through the blood-brain barrier, alpha-HCH exposed brain and liver tissue slices were compared. Concentrations in the brain slices did not decrease with PB pretreatment but did decrease in the liver slices. Enantiomeric ratios in the brain slices averaged 1.11 +/- 0.02 and were 0.76 +/- 0.03 in liver slices for the PB pretreated rats. These data indicate that the enantioselective metabolism of alpha-HCH by the brain is not the mechanism responsible for high ERs in this tissue.

Air samples were analyzed from urban, rural, and remote sites near the Great Lakes to investigate the occurrence, concentrations, and spatial and temporal differences of polybrominated diphenyl ethers (PBDE) in air. The concentrations of PBDEs were compared to those of other organohalogen compounds such as PCBs and organochlorine pesticides. The samples were collected in 1997-1999 as part of the Integrated Atmospheric Deposition Network (IADN). To minimize the variability of the data, we selected only samples taken when the atmospheric temperature was 20 +/- 3 degrees C. PBDEs were found in all samples, indicating that these compounds are widely distributed and that they can be transported through the atmosphere to remote areas. The total concentrations of PBDEs were similar to some of the organochlorine pesticides such as sigmaDDT and ranged from 5 pg/m3 near Lake Superior to about 52 pg/m3 in Chicago. In fact, the spatial trend was well correlated to those of PCBs. Our results indicate a relatively constant level from mid-1997 to mid-1999. At 20 +/- 3 degrees C, about 80% of the tetrabromo homologues are in the gas phase and about 70% of the hexabromo homologues are associated with the particle phase. Thus, particle-to-gas partitioning in the atmosphere is an important process for these compounds.

Toxaphene was a heavily used, broad-spectrum insecticide, which was banned in most countries in the 1980s. Early data suggested that a limited number of congeners in the technical mixture were responsible for its toxicity to insects. However, toxaphene research has historically focused on analyzing total toxaphene, largely due to insufficient analytical methodology to measure the individual congeners. In recent years, congener-specific toxaphene research has flourished due to analytical advances leading to the identification of several congeners, about 25 of which are commercially available. However, the high price of these standards may inhibit toxaphene research in some laboratories. We report here the methylene retention indexes for 28 isolated toxaphene congeners. When used in conjunction with mass spectrometry, methylene retention indexes provide an alternative method for identifying these compounds when direct comparison with standard compounds is not practical.

Toxaphene is a complex mixture of at least 600 hexa- to decachlorinated bornanes and bornenes, which was used as an insecticide from the late 1950s to the early 1980s. Like PCBs and other environmentally persistent organochlorine pesticides, toxaphene is ubiquitous in the environment. Toxaphene's complex composition makes its accurate quantitation difficult. We report here an automatic, gas chromatographic mass spectrometry method (using electron capture negative ionization) that is precise and fast. This method is implemented by a small QBasic program that compares peak area ratios to the predicted chlorine isotopic ion ratios. This method decreases the time required for analysis while maintaining precise quantitation. The method is verified with standard and unknown samples contaminated with various amounts of other organochlorine pesticide interferents.