Significance of biotransformation and excretion on the enantioselective bioaccumulation of hexabromocyclododecane (HBCDD) in laying hens and developing chicken embryos.

Although (-)-α-hexabromocyclododecane (HBCDD) and (+)-γ-HBCDD are preferentially enriched in chickens, the key factors contributing to their selective bioaccumulation in hens and their potential biotransformation in developing chicken embryos remain unclear. Herein, in vivo and in ovo exposure experiments using hens and fertilized eggs were conducted to investigate the absorption, excretion, and biotransformation of HBCDDs in chickens. γ-HBCDD (76%) exhibited a higher absorption efficiency than α- (22%) and ß- (69%) HBCDDs. However, α-HBCDD was dominant in hen tissues, although γ-HBCDD accounted for >75% in the spiked feed. Moreover, chicken embryos biotransformed approximately 9.5% and 11.7% of absorbed α- and γ-HBCDDs, respectively, implying that diastereomer-selective elimination causes the predominance of α-HBCDD in hens. The concentration and enantiomer fraction (EF) of α-HBCDD in laid eggs were significantly positively correlated, suggesting enantioselective elimination. The EFs of α- and γ-HBCDDs varied between feces from the exposure and depuration periods, indicating the preferred excretion of (+)-α- and (-)-γ-HBCDDs. Furthermore, the enantioselective biotransformation of (-)-γ-HBCDD was confirmed in developing chicken embryos. These results show that excretion and biotransformation contribute to the diastereomer- and enantiomer-selective bioaccumulation of HBCDDs in chickens; The results may improve our understanding of the environmental fate and ecological risks of HBCDDs in biota.

Organophosphate flame retardants and diesters in the urine of e-waste dismantling workers: associations with indoor dust and implications for urinary biomonitoring.

Indoor dust ingestion is one of the main pathways for human exposure to organophosphate flame retardants (PFRs). The urinary concentrations of diesters (DAPs) are usually used as biomarkers to assess human exposure to PFRs. In this study, the PFR and DAP levels were measured in morning and evening urine samples of 30 workers from an e-waste dismantling site in southern China. The indoor dust samples were also collected from workshops and houses for analyzing associations between PFR and DAP levels in urine and dust. Tris(1-chloro-2-propyl) phosphate (TCIPP) and triphenyl phosphate (TPHP) were the dominant PFRs in dust, while bis(2-chloroethyl) phosphate (BCEP) and diphenyl phosphate (DPHP) were the major DAPs in dust. A significant positive correlation was observed between TPHP and DPHP concentrations in dust (p < 0.001), suggesting their potentially same source and the degradation of TPHP to form DPHP. TCIPP and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were the predominant PFRs, and BCEP, bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), and DPHP were the main DAPs in both the morning and evening urine samples. The DPHP levels in evening urine samples were significantly correlated with TPHP and DPHP levels (p < 0.01) in dust. A similar correlation was found for the BCEP levels in the evening urine samples and the TCEP and BCEP levels (p < 0.01) in dust. These results indicated that in addition to being biotransformed from their respective parent PFRs, direct ingestion from indoor dust could also be the potential source for urinary DPHP and BCEP. Since relatively low detection frequencies were observed for bis(1-chloro-2-propyl) phosphate (BCIPP) and bis(butoxyethyl) phosphate (BBOEP) in urine, they may not be the major metabolites of TCIPP and tris(2-butoxyethyl) phosphate (TBOEP), respectively, in the human body. However, BDCIPP can be considered a useful biomarker because it is a unique metabolite of TDCIPP and has high detection frequencies in urine samples. The results of this study indicated the limitations of solely using urinary DAPs as biomarkers for the evaluation of human exposure to PFRs, and certain PFRs as well as hydroxylated PFRs (OH-PFRs) should also be considered for urinary biomonitoring in future studies.

Capillary electrophoresis with in-capillary solid-phase extraction sample cleanup.

An in-capillary, solid-phase extraction (SPE)-capillary electrophoresis (CE) method, with not only high preconcentration factor but also no adsorption on the inner capillary wall of absorbing species in real complex samples, has been developed with a hole-opened capillary. The SPE sorbents approximately 3 mm in length was packed in the inlet end of the capillary. A hole approximately 30 microm in diameter was opened after the sorbents on the capillary. Sample solutions were loaded from the inlet end, and the sample wastes flowed out from the hole. After a certain time of the sample loading, a 1.5-mm-long methanol plug was introduced from the inlet end and forced to pass by the sorbents and the hole. Then, a separation voltage was applied between the hole and the outlet end of the capillary to carry out normal CE. When the sample loading time was 120 min, CE peak heights of the 2,4-dichlorophenol and 2,4,5-trichlorophenol were proportional to their concentration in a range of 0.08-5 ng/mL, and their detection limits were 25 and 17 pg/mL, respectively. A 16,000-fold sensitivity enhancement was obtained for CE of the chlorophenols with only a little decrease in CE separation efficiency. It was also demonstrated with the mixture of the chlorophenols and a surfactant cetyltrimethylammonium bromide that the present method could eliminate the adsorption problem of absorbing species on the inner wall during sample loading. Furthermore, the SPE-CE was directly applied to determination of chlorophenols on the level of 0.02 ppb in downstream water of a river, and the results agreed well with those obtained with off-line SPE-HPLC experiments.

In-capillary solid-phase extraction-capillary electrophoresis for the determination of chlorophenols in water.

A novel CE method combined with SPE in a single capillary was developed for analysis of chlorophenols in water. A frit of 0.5 mm was first made by a sol-gel method, followed by packing a SPE sorbent in the inlet end of the capillary. Two phenol derivatives, 2,4-dichlorophenol and 2,4,5-trichlorophenol, were used as the model compounds. By loading sample solutions into the capillary, the two chlorophenols were extracted into the sorbent. They were desorbed by injecting only about 4 nL of methanol. Finally, the analytes were separated by conventional CE. The technique provided a concentration enhancement factor of over 4000-fold for both chlorophenols. The detection limits (S/N = 3) of 2,4-dichlorophenol and 2,4,5-trichlorophenol were determined to be 0.1 ng/mL and 0.07 ng/mL, respectively. For replicate analyses of 5 ng/mL of 2,4-dichlorophenol, within-day and between-day RSDs of migration time, peak height and peak area were in the range of 1.8-2.0%, 4.0-4.4% and 4.1-4.6%, respectively. The method shows wide linear range, acceptable reproducibility and excellent sensitivity, and it was applied to the analyses of spiked river water samples. The capillary packed with the SPE sorbents can be used for more than 400 runs without performance deterioration.

Isoelectric focusing sample injection for capillary zone electrophoresis in a fused silica capillary.

An improvement has been made to couple isoelectric focusing (IEF) sample injection and capillary zone electrophoresis in an untreated fused silica capillary. Electroosmotic flow is efficiently prevented by simply using a rubber block at the outlet end of the capillary during IEF sample injection. The experimental conditions that affect the concentration effect are discussed. A concentration enhancement factor of over 100-fold can be easily obtained for two model proteins: lysozyme and ribonuclease A.

Isoelectric focusing sample injection for capillary electrophoresis of proteins.

Carrier ampholyte-free isoelectric focusing (IEF) sample injection (concentration) for capillary electrophoresis (CE) is realized in a single capillary. A short section of porous capillary wall was made near the injection end of a capillary by HF etching. In the etching process, an electric voltage was applied across the etching capillary wall and electric current was monitored. When an electric current through the etching capillary was observed, the capillary wall became porous. The etched part was fixed in a vial, where NaOH solution with a certain concentration was added during the sample injection. The whole capillary was filled with pH 3.0 running buffer. The inlet end vial was filled with protein sample dissolved in the running buffer. An electric voltage was applied across the inlet end vial and etched porous wall. A neutralization reaction occurs at the boundary (interface) of the fronts of H+ and OH-. A pH step or sharp pH gradient exists across the boundary. When positive protein ions electromigrate to the boundary from the sample vial, they are isoelectricelly focused at points corresponding to their pH. After a certain period of concentration, a high voltage is applied across the whole capillary and a conventional CE is followed. An over 100-fold concentration factor has been easily obtained for three model proteins (bovine serum albumin, lysozyme, ribonuclease A). Furthermore, the IEF sample concentration and its dynamics have been visually observed with the whole-column imaging technique. Its merits and remaining problem have been discussed, too.