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.

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 After a prescribed period of time, the acceptor solution inside the fiber was withdrawn into the microsyringe and directly injected into the HPLC system for analysis.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.

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.

A highly chlorinated flame retardant, Dechlorane Plus (DP), was detected and identified in ambient air, fish, and sediment samples from the Great Lakes region. The identity of this compound was confirmed by comparing its gas chromatographic retention times and mass spectra with those of authentic material. This compound exists as two gas chromatographically separable stereoisomers (syn and anti), the structures of which were characterized by one-and two-dimensional proton nuclear magnetic resonance. DP was detected in most air samples, even at remote sites. The atmospheric DP concentrations were higher at the eastern Great Lakes sites (Sturgeon Point, NY, and Cleveland, OH) than those at the western Great Lakes sites (Eagle Harbor, MI, Chicago, IL, and Sleeping Bear Dunes, MI). At the Sturgeon Point site, DP concentrations once reached 490 pg/m3. DP atmospheric Concentrations were comparable to those of BDE-209 at the eastern Great Lakes sites. DP was also found in sediment cores from Lakes Michigan and Erie. The peak DP concentrations were comparable to BDE-209 concentrations in the sediment core from Lake Erie but were about 30 times lower than BDE- 209 concentrations in the core from Lake Michigan. In the sediment cores, the DP concentrations peaked around 1975-1980, and the surficial concentrations were 10-80% of peak concentrations. Higher DP concentrations in air samples from Sturgeon Point, NY, and in the sediment core from Lake Erie suggest that DP's manufacturing facility in Niagara Falls, NY, may be a source. DP was also detected in archived fish (walleye) from Lake Erie, suggesting that this compound is, at least partially, bioavailable.