Kumiko Yaguchi

Spatially detailed survey on pollution by multiple perfluorinated compounds in the Tokyo Bay basin of Japan.

Pollution from 35 perfluorinated compounds (PFCs) in the water of the Tokyo Bay basin was examined. The water in the basin contained relatively high levels of perfluorononanoate (PFNA), perfluorooctanoate (PFOA), and perfluorooctane sulfonate (PFOS) compared to the other PFCs, which were present at concentrations of 20.1 ng/L, 6.7 ng/L, and 5.8 ng/L, respectively. In contrast, the concentrations of their precursors and degradation products were an order of magnitude lower. Sewage treatment plant (STP) effluent in the area also contained high levels of PFNA compared with the river water samples (Mann-Whitney U-test, p<0.0002). From a spatial aspect, increases in PFC pollution levels correlated with increased urbanization in the study area suggested that there are nonpoint source contributors to the PFC pollution in this area. Branched isomers of the PFCs were also quantified. Samples that contained high concentrations of perfluoroalkyl carboxylates (PFCA) showed lower proportions of its branched isomer. This indicates that the branched isomers are more prominent in the area with lower PFC pollution. This analysis was beneficial for estimating the individual contributions of different PFCA production processes. This survey provided new information on the sources, spatial distribution, and behavioral characteristics of PFC pollutants in this area.

Determination of pesticides in water by capillary gas chromatography with splitless injection of large sample volumes

Abstract A large-volume injection for a capillary gas chromatograph equipped with an electron-capture, nitrogen—phosphorus-selective (NPD) or flame photometric detector is proposed for the determination of pesticides. The cold-trap column, a deactivated fused-silica column (3 m × 0.53 mm I.D.), was attached to the analytical column (30 m) and the regulation column (3 cm), DB-5, both of 0.25 mm I.D. with film thickness 0.25 μm, with a dual-outlet splitter. The regulation column was connected with the solvent-diversion column, a deactivated fused-silica column (2 m × 0.53 mm I.D.), which was led out of the column oven and attached to an electromagnetic valve. By opening the valve in the splitless mode, the pesticides slowly injected in n-hexane in a volume from 25 to 150, μl were trapped in the cold-trap column, and a large volume of n-hexane was almost all diverted from the gas chromatograph through the diversion column. The trapped pesticides were introduced to the analytical column by closing the valve. Twenty-five pesticides, scattered on a golf course in Japan, were determined at concentrations from 1 to 100 ng/ml in n-hexane. The reproducibility of separation of the pesticides by the proposed method was similar to that of normal splitiess (1-μl) injection. The proposed method was applied to the screening of the pesticides in groundwater after liquid—liquid extraction with dichloromethane; the pesticides could be determined at levels lower than 1 μg/l in a 20-ml water sample.

Spatial distribution and loading amounts of particle sorbed and dissolved perfluorinated compounds in the basin of Tokyo Bay.

In this study, we analyzed over 30 types of PFCs, including precursors in both the dissolved phase and particle solid phase, in 50 samples of river water collected from throughout the Tokyo Bay basin. PFCs were detected in suspended solids (SSs) at levels ranging from <0.003-4.4 ng L(-1) (0.11-2470 ng g(-1) dry weight). The concentrations of PFCs in the SS were one to two order(s) of magnitude lower than those of PFCs in the dissolved phase. Relatively high levels of PFCs (total of 35 PFCs) in SS were observed in urbanized areas. The concentration of PFCAs, including PFOA and PFNA, were significantly correlated with the geographic index as artificial area (R(2) of the linear regression curve in a double logarithmic plot: 0.09-0.55). Conversely, PFOS and FOSA were significantly correlated with the arterial traffic area (R(2) in a double logarithmic plot: 0.29-0.55). Those spatial trends were similar to the trends in dissolved PFCs. We estimated the loading amount of PFCs into Tokyo Bay from six main rivers and found that more than 90% of the total PFCs reached Tokyo Bay in the dissolved phase. However, 40.0-83.5% of the long chain PFCAs (C12-C15), were transported as particle sorbed PFCs. Rain runoff events might increase the loading amount of PFCs in SS. Overall, the results presented herein indicate that greater attention should be given to PFCs, especially for longer chain PFCs in SS in addition to dissolved PFCs.

Cytotoxic effects of 2,6-di-tert-butyl-4-methylphenyl N-methylcarbamate (terbutol) herbicide on hepatocytes and mitochondria isolated from male rats

The cytotoxic effects of 2,6-di-tert-butyl-4-methylphenyl N-methylcarbamate (terbutol) and its major metabolites were investigated in freshly isolated rat hepatocytes. Terbutol and its metabolite, especially 2,6-di-tert-butyl-4-methylphenyl carbamate (N-demethylterbutol), at a concentration of 1.0 mM resulted in a time dependent cell killing accompanied by losses of intracellular ATP, protein thiols, and glutathione (GSH) and the accumulation of oxidized GSH. Supplementation of the hepatocyte suspension with 5 mM N-acetylcysteine, a precursor of intracellular GSH, inhibited the cytotoxicity of N-demethylterbutol. In mitochondria isolated from rat liver, terbutol and its metabolites impaired respiration related to oxidative phosphorylation and the potency of their toxicity is associated with impairment of mitochondrial respiration. These results indicate that N-demethylterbutol is the most cytotoxic followed by terbutol and other metabolites, and that both the mitochondrial respiratory system and protein thiols are important targets for these compounds.

Screening methods for asulam, oxine-copper and thiram in water by high-performance liquid chromatography after enrichment with a minicolumn

Abstract A syringe-type minicolumn containing 40 μl of C 18 bonded silica was used for pretreatment of the samples in the determination of methyl-N-(aminophenylsulphonyl)carbamate (asulam), bis(8-quinolinolato)copper (oxine-Cu) and bis(dimethylthiocarbamoyl)disulphide (thiram) in ground, tap and river water by reversed-phase high-performance liquid chromatography (HPLC). The low levels of pesticides were adsorbed on the minicolumn, which was then connected to the injector of the HPLC system, and directly injected into the loop by eluting with a small amount of eluent. Average recoveries of asulam, oxine-Cu and thiram in water samples at concentrations of 5 μg/l were 91.5, 77.1 and 87.3%, respectively. The detection limits of asulam from 300 μl of water sample and of oxine-Cu and thiram from 1 ml were 0.2, 1.0 and 0.5 μg/l, respectively. It took only about 10 min to obtain a chromatogram on HPLC, including sample pretreatment. The syringe-type minicolumn was useful to eliminate compounds coexisting in water. This small-scale procedure enabled the sample volume required and the amount of organic solvent for elution to be reduced.