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.

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.

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

Liquid-liquid-liquid microextraction (LLLME) with hollow fibers in high-performance liquid chromatography (HPLC) has been applied as a rapid and sensitive quantitative method for the detection of four aromatic amines (3-nitroaniline, 4-chloroaniline, 4-bromoaniline and 3,4-dichloroaniline) in environmental water samples. The preconcentration procedure was induced by the pH difference inside and outside the hollow fiber. The target compounds were extracted from 4-ml aqueous sample (donor solution, pH～13) through a microfilm of organic solvent (di-n-hexyl ether), immobilized in the pores of a hollow fiber (1.5cm length 30.6mm I.D.), and finally into 4 ml of acid acceptor solution inside the fiber. After a prescribed period of time, the acceptor solution inside the fiber was withdrawn into the microsyringe and directly injected into the HPLC system for analysis. Factors relevant to the extraction procedure were studied. Up to 500-fold enrichment of analytes could be obtained under the optimized conditions (donor solution: 0.1M sodium hydroxide solution with 20% sodium chloride and 2% acetone; organic phase: di-n-hexyl ether; acceptor solution: 0.5M hydrochloric acid and 500μM 18-crown-6 ether; extraction time of 30min; stirring at 1000rev./min). The procedure also served as a sample clean-up step. The influence of humic acid on the extraction efficiency was also investigated, and more than 85% relative recoveries of the analytes at two different concentrations (20 and 100mg/l) were achieved at various concentration of humic acid. This technique is a low cost, simple and fast approach to the analysis of polar compounds in aqueous samples.

This paper describes a novel method that applies fieldamplified sample injection (FASI) in micellar electrokinetic chromatography (MEKC) with a low pH background electrolyte (BGE). Six phenolic compounds prepared in water or NaOH solution were used as the test analytes. Sample was injected electrokinetically after the introduction of a plug of water. During the injection, the water plug was pumped out of the capillary inlet by the electroosmotic flow, and the phenolic anions migrated very quickly in the direction of the outlet. When the anions reached the boundary between the water plug and BGE, they were neutralized and ceased moving. Thereafter, MEKC was initiated for the separation. This on-line preconcentration method could be conveniently coupled with a liquid-liquid-liquid microextraction procedure, in which a hollow fiber was used as an extraction solvent support to extract the analytes from the water sample. The acceptor phase consisted of 8mM NaOH. After extraction, the extract was analyzed directly by MEKC, as described.