Kimiyoshi Kitamura

Modified clean-up for PBDD, PBDF and PBDE with an active carbon column––its application to sediments

A clean-up method for polybrominated dibenzo-p-dioxins (PBDDs), dibenzofurans (PBDFs) and diphenyl ethers (PBDEs) was modified using combinations of multi-layered silica gel, Florisil and active carbon columns. By using active carbon column chromatography in the final procedure, PBDEs were well separated from PBDD/Fs in an elution test with reference standards. We report the application of this method to sediment samples taken from industrialized areas in Japan. These sediments contained PBDEs ranging in concentration from 13 to 2394 pg/g, dry wt. PBDEs did not interfere with the quantification of PBDD/Fs. In addition, PBDEs found in the PBDD/F fraction did not interfere with the identification of PBDFs using the HRGC/HRMS separation method. Some 2,3,7,8-tetra- to hexabrominated dioxins and furans were also detected in the sediment samples.

Particle-size-fractioned transfer of dioxins from sediments to water columns by resuspension process

Particle-size-fractioned transfer of dioxins from sediments to water columns by resuspension process was investigated, using supernatant samples obtained from shaking experiments of sediment-water pairs simulating natural disturbances. The concentrations (dry-matter mass basis) of individual compounds (C(fraction)) in two particle size fractions (0.1-1 and 1-10 microm) in the supernatants were generally slightly higher than those in the original sediment (C(sed)). C(fraction)/C(sed) ratios ranged from 0.45 to 5.9 (median 1.5) without consistent differences among congener groups or consistent correlations against the number of chlorine atoms. The dioxin concentrations in the water column associated with the remaining sediment particles can therefore be estimated by those in the original sediment and by the concentration of suspended sediment particles in the water. The concentration of each compound in the remaining sediment particles (mostly 0.1-10 microm in size) can be roughly estimated by multiplying the concentration in the original sediment by 1.5.

Effective pretreatment of human serum samples for dioxin analysis by solid phase extraction and blue-chitin column cleanup.

For the analysis of dioxins, polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/Fs) and coplanar polychlorinated biphenyls (Co-PCBs), devising simple and economical methods is important, especially for mass screening of human exposure. Pretreatment of samples, namely the extraction and cleanup methods that are widely used at present, needs to be improved for savings in time, manpower, and solvent consumption. In the present study, we applied solid phase extraction (SPE) using octadecyl (C18) and a blue-chitin column in place of liquid-liquid extraction (LE) and an active-carbon column with serum samples, frequently used for assessment of human exposure. Efficacy of the new pretreatment methods was demonstrated by successful high resolution gas chromatography-high resolution mass spectrometry (HRGC-HRMS) of the major 17 PCDDs/Fs and 12 Co-PCBs that are on the list of WHO/IPCS (1997) hazardous dioxins with toxic equivalent factor (TEF) values. SPE is timesaving and requires less manpower and organic solvent as compared with the LE that is presently widely used. Concerning cleanup with blue-chitin, the amount of toluene applied as eluent could be reduced to 1/3, as compared with the active-carbon case. The combination of SPE and blue-chitin for pretreatment of serum saves time and manpower, is accurate and uses less organic solvent than LE with active carbon cleanup.

A method to circumvent the lot number of activated carbon affecting the performance of activated carbon silica gel columns used for cleanup of blood samples for analysis of 29 hazardous organochlorine compounds

We have previously described the use of a tandem simplified multilayer silica gel-activated carbon dispersed silica gel (TS-ML-AC) column for the cleanup of blood samples for the analysis of 29 hazardous organochlorine compounds (OCs)--the 17 major polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/DFs) and 4 non-ortho- and 8 mono-ortho-polychlorinated biphenyls (PCBs). We noted that the performance of the activated carbon-silica gel (ACS) column (lower column) varied with the lot number of the ACS. In this study, we compared the elution profiles of OCs eluted on 5 ACS columns, each with a different ACS lot number, and found that only mono-ortho-PCBs #114 and #123 were affected by lot number. The problem was that the 50 ml of n-hexane required to elute all the OCs from the simplified multilayer silica gel (MLS) column (upper column) into the AC column (lower column) also eluted varying amounts of PCBs #114 and #123 from the ACS column by ACS lot number. Although we could prevent PCBs #114 and #123 from being eluted from the ACS column by reducing the n-hexane volume to 10 ml, this volume was not sufficient to elute all the OCs from the MLS column. We solved this by separating the two columns; the sample solution was eluted with 50 ml of n-hexane from the MLS column, this eluate was concentrated to about 0.3 ml using a rotary evaporator, and then the concentrated solution was cleaned up on the ACS column. The recovery rates of #114 and #123 from blood samples were above 70% and the relative standard deviations of their concentration were below 10%, irrespective of the lot number, compared with recovery rates of 45-79% for #114 and 59-89% for #123, and relative standard deviations of their concentration above 15% when 50 ml of n-hexane was run through the tandem column. Our modified method affords reliable and reproducible cleanup of blood samples for analysis of 29 OCs, irrespective of the ACS lot number.