The history of polybrominated diphenyl ethers (PBDEs) and the major polybrominated biphenyl congener (BB-153) was studied in dated sediment cores taken from Lakes Michigan and Erie. The surficial concentration of total PBDE (320ng/g dry weight) in Lake Michigan was about 10times higher than that in Lake Erie (40ng/g) and in Lake Superior (12ng/g). The concentrations of total PBDEs in these sediments have increased rapidly, with doubling times of 5-10 years, reflecting the increasing market demand for these flame retardants over the last 30 years. BDE-209 was found to be the predominant congener in both sediment cores, making up 95-99% of the total PBDE load. The inventories of total PBDEs in Lakes Michigan and Erie were 190 and 40ng/cm2, respectively. The total burdens of these compounds in the sediment of Lakes Michigan and Erie were 110 and 10 metric tons, espectively. We estimate that the total burden of these compounds in all of the Great Lakes is on the order of 200 tons. In both lakes, BB-153 was found to increase rapidly during the 1970s and to peak around 1980.

A simple preconcentration and clean-up liquid-liquid-liquid microextraction of aromatic amines is described in this paper. The compounds were extracted from 2.0µl aqueous samples (donor phase) into an organic phase, layered on the donor phase, and then back extracted to a microdrop of aqueous receiving phase, suspended in the organic phase. After extraction, the microdrop was injected into the HPLC system directly for analysis. Optimal conditions of the extraction were donor phase (a): 2 ml of water sample adjusted to pH 13 with NaOH-NaCl; organic phase (o), 150ml ethyl acetate; and 1 receiving phase (a) of 2µl aqueous solution at pH 2.1. The a→o extraction time was 15min and for o→a, 30s. 212 18-Crown-6 ether, which can complex with amine, was added to the aqueous receiving phase to improve the extraction performance. Enrichment factors ranged from 218 (for 4-nitroaniline) to 378 (for 4-chloro-2-aniline). The calibration curve 2 for these anilines was linear within the range 2.5ng/ml-2.5mg/ml (r 50.998). Detection limits ranged from 0.85 to 1.80ng/ml (at S/N53). This procedure can be a selective preconcentration method for aromatic amines present in water samples. 2002 Elsevier Science B.V. All rights reserved.

The release of fluoride is an impodant factor in evaluating a composite restorative material due to its anticariogenic effect, Field amplified stacking injection in capillary electrophoresis was studied to determine the concentration of fluoride released from dental restorative materials, A detection limit of 20ng/mL was obtained with good reproducibility (relative standard deviation <4%), The method was applied to the ana-lysis of fluoride released from four different types of commercially available dental composites ever 28 days. Resutis showed that fiald-amplified stacking injection-capil-lary electrophoresis was effective in monitoring the fluonde release process and pro- duct quality of different kinds of restorative materials,

To explore the geographical distribution and temporal trends of polybrominated diphenyl ethers (PBDEs) in the Great Lakes, lake trout from Lakes Superior, Michigan, Huron, and Ontario and walleye from Lake Erie, collected during the period of 1980-2000, were analyzed. The concentrations of fifteen PBDE congeners and one polybrominated biphenyl (PBB-153) were determined in each fish sample. Lake trout from Lakes Michigan and Ontario had the highest

Two brominated flame retardants, 1,2-bis (2,4,6-tribromophenoxy) ethane (TBE) and 2,3,4,5,6-pentabromoethylbenzene (PEB), were detected and identified in ambient air samples from various sites in the United States. The identifications were confirmed by comparing the gas chromatographic retention times and mass spectra of the compounds found in the environment with those of authentic materials. Generally, the TBE concentrations in air were comparable to those of tetra-through hexabrominated diphenyl ethers (PBDEs) and often higher than those of decabromodiphenyl ether (BDE-209). The atmospheric TBE concentrations at locations in the southern United States were higher than those in the northern United States. TBE was also found in a sediment core from Lake Michigan; the concentrations of TBE increased with time, were lower than those of BDE-209, but were 10 times higher than the sum of BDE-47, -99, and -100. The maximum PEB concentration in Chicago air was 550pg/m3, which was 10 times higher than the concentration of total PBDEs in this sample. In general, the concentrations of PEB in air samples were low but detectable and were less than those of PBDEs. PEB was not found in the sediment core from Lake Michigan. These occurrences of relatively high concentrations of TBE and PEB in environmental samples may reflect the increasing usage of these compounds as flame retardants.